kohlenstoff experiment

Periodensystem

Der boyle-versuch mit aktivkohle.

Zielsetzung

• Du untersuchst die Reaktion von Kohlenstoff und Sauerstoff.

Hinweise zum Experiment

Damit in Chemie bzw. beim Experimentieren keine Unfälle passieren, musst du auf die Sicherheit achten. Die Sicherheit ist immer wichtig, wenn du in einem Fachraum oder Labor bist. Bitte beachte bei allen Experimenten die  Hinweise zur Sicherheit im Labor .  Die Durchführung des Experiments erfordert eine Gefährdungsbeurteilung durch die Lehrkraft.

• Rundkolben \(\ce{(1000 ml)}\)
• Gummistopfen, Klebeband etc. um den Luftballon am Rundkolben zu fixieren
• Bunsenbrenner

Chemikalien

Versuchsaufbau/Durchführung

• Stelle den Rundkolben mit dem Korkring auf die Laborwaage.
• Gib etwa \(\ce{200 - 300\,mg}\) Aktivkohle in den Rundkolben.
• Spüle den Rundkolben mit Sauerstoff aus und verschließe den Rundkolben mit dem Luftballon.
• Befestige den Luftballon ggf. mit Klebeband o. ä., um den Luftballon zu fixieren und den Rundkolben luftdicht zu verschließen.
• Wiege nun den Rundkolben mit Luftballon und notiere das Gewicht.

• Befestige die Klammer am Hals des Rundkolbens.
• Zünde die blaue rauschende Flamme des Gasbrenners an.
• Erhitze mit der Brennerflamme die Aktivkohle und schüttle den Rundkolben dabei leicht.
• Höhe auf zu erhitzen, wenn du keine Reste der Aktivkohle mehr sehen kannst.

Stelle den Rundkolben mit dem Luftballon wieder auf den Korkring auf der Laborwaage. Entferne die Klemme und wiege die Masse des Rundkolbens mit dem Luftballon. Was fällt dir auf?

Führe den Versuch durch. Was kannst du beobachten?

Beobachtung

Beim Erhitzen fängt die Aktivkohle nach kurzer Zeit an, zu glühen. Dabei ist zu beobachten, dass die Masse der Aktivkohle abnimmt, bis keine Aktivkohle mehr zu sehen ist. Gleichzeitig bläst sich der Luftballon auf und wird prall.

Abb. 4 Der Boyle-Versuch mit Aktivkohle

Auch wenn du die Aktivkohle nicht mehr sehen kannst, sind die Kohlenstoffatome der Aktivkohle nicht verschwunden. Beim Erhitzen der Aktivkohle reagieren Kohlenstoff und Sauerstoff zu Kohlenstoffdioxid.

\(\ce{C + O2 -> CO2}\)

Das Kohlenstoffdioxid ist gasförmig. Der Luftballon bläht sich auf, weil das Gas im Rundkolben erhitzt wird. Es dehnt sich dadurch aus. Das Gas kann nicht entweichen, weil der Rundkolben und der Luftballon ein abgeschlossenes System bilden. Lässt du den Rundkolben nach dem Experiment abkühlen, kühlt auch das Gas im Inneren ab und zieht sich wieder zusammen, sodass auch der Luftballon sich wieder zusammen zieht. Insgesamt ist vor und nach dem Experiment die gleiche Anzahl an Atomen in dem System vorhanden. Deswegen verändert sich die Masse auch nicht. Nichts kann verschwinden, auch wenn wir es mit unseren Sinnen nicht mehr wahrnehmen können. Das ist das Gesetz zur Erhaltung der Masse.

Vorheriger Versuch

Nächster versuch, aus unseren projekten:.

Das Portal für den Physikunterricht

Das Portal für den Wirtschaftsunterricht

Ideen für den MINT-Unterricht

Schülerstipendium für Jugendliche

Ihr Kontakt zu uns:

Joachim Herz Stiftung

Langenhorner Chaussee 384

22419 Hamburg

T. +49 40 533295-0

F. +49 40 533295-77

[email protected]

• Experimente

Material für Klasse 9 - 10

Alkali- und erdalkalimetalle experimente anzeigen.

Alkalimetalle Experimente anzeigen

Alkalimetalle III Experimente anzeigen

Alkane, Alkohole, ungesättigte Kohlenwasserstoffe Experimente anzeigen

Alkohole und deren Eigenschaften Experimente anzeigen

Alkoholgehaltsbestimmung und Alkoholherstellung Experimente anzeigen

Brennstoffzelle Experimente anzeigen

Die Brennstoffzelle Experimente anzeigen

Eigenschaften gesättigter Kohlenwasserstoffe Experimente anzeigen

Eigenschaften und Reaktionen von gesättigten Kohlenwasserstoffen Experimente anzeigen

Einfache Elektrolysen und Leitfähigkeit Experimente anzeigen

Elektrolyse Experimente anzeigen

Elementfamilien - Nachweise in Alltagsprodukten Experimente anzeigen

Energiespeicher Experimente anzeigen

Energiespeicherung Experimente anzeigen

Erdalkalimetalle Experimente anzeigen

Erdölraffination und Energieträgergewinnung Experimente anzeigen

Erweiterter Redoxbegriff Experimente anzeigen

Halogene Experimente anzeigen

Halogene, Nachweise in Alltagsgegenständen Experimente anzeigen

Halogene, Nachweise in Alltagsprodukten Experimente anzeigen

Laserinduzierte Fluoreszenz von Iod Experimente anzeigen

Leitfähigkeit und einfache Elektrolyse Experimente anzeigen

Leitfähigkeit und einfache Elektrolysen Experimente anzeigen

Metalle und Nichtmetalle Experimente anzeigen

Methan und Erdgas Experimente anzeigen

Methan und Erdgas III Experimente anzeigen

Nachweisreaktionen Experimente anzeigen

Nano in Alltagsprodukten Experimente anzeigen

Nanotechnologie, Nano im Alltag Experimente anzeigen

PH-Wert Experimente anzeigen

Qualitativer Nachweis von Säuren und Basen Experimente anzeigen

Reaktion von Säuren und Basen mit Metallen und Nichtmetallen Experimente anzeigen

Reaktionen von Metallen und Metallverbindungen sowie von Nichtmetallen (Ammoniak) Experimente anzeigen

Salz und Salzbildung Experimente anzeigen

Salze und Salzbildung Experimente anzeigen

Salze und Salzbildung III Experimente anzeigen

Saure und alkalische Haushaltssubstanzen III Experimente anzeigen

Saure und alkalische Substanzen im Haushalt Experimente anzeigen

Säuren und Basen im Haushalt Experimente anzeigen

Schwefelsäure Experimente anzeigen

Stoffkreisläufe Experimente anzeigen

Titration Experimente anzeigen

Titrationen (Alltagschemikalien) Experimente anzeigen

Vom Alkan zum Alkohol Experimente anzeigen

Vom Alkohol zum Alken Experimente anzeigen

Vom Schwefel zur Schwefelsäure Experimente anzeigen

Von Arrhenius bis Brönstedt Experimente anzeigen

Von Arrhenius zu Brönsted Experimente anzeigen

Von Arrhenius zu Brönstedt II Experimente anzeigen

Von schwefel zur schwefelsäure experimente anzeigen.

Wasserhärtebestimmung Experimente anzeigen

Wasserhärtebestimmung II Experimente anzeigen

Copyright und Lizenzen

Alle Rechte an den Inhalten dieser eLearning-Materialien liegen beim Autor oder den jeweiligen Urheberrechtsinhabern. Sämtliche Bilder und Texte sind entweder vom Autor selbst fotografiert oder verfasst oder sind gemeinfrei, es sei denn, es ist eine andere Quelle angegeben. Die gesammelten/vollständigen Literaturverzeichnisse der einzelnen Versuche sind jeweils in den entsprechenden Gesamtprotokollen zu finden.

Haftungsausschluss

Die Benutzung der hier vorliegenden Informationen geschieht auf vollkommen eigene Verantwortung. Haftung für Schäden oder Verluste, die beim Umgang mit den hier beschriebenen Stoffen oder bei der Durchführung von chemischen Versuchen entstehen, ist ausgeschlossen; ebenso wie Schadensersatzforderungen oder Gewährleistungsansprüche aufgrund falscher oder fehlender Angaben. Die Angaben zu den Stoffen und die Experimentieranleitungen wurden jedoch sorgfältig und nach bestem Gewissen erstellt und sind in jedem Falle zu beachten.

• Games & Quizzes
• History & Society
• Science & Tech
• Biographies
• Animals & Nature
• Geography & Travel
• Arts & Culture
• On This Day
• One Good Fact
• New Articles
• Lifestyles & Social Issues
• Philosophy & Religion
• Politics, Law & Government
• World History
• Health & Medicine
• Browse Biographies
• Birds, Reptiles & Other Vertebrates
• Bugs, Mollusks & Other Invertebrates
• Environment
• Fossils & Geologic Time
• Entertainment & Pop Culture
• Sports & Recreation
• Visual Arts
• Demystified
• Image Galleries
• Infographics
• Top Questions
• Britannica Kids
• Saving Earth
• Space Next 50
• Student Center
• Introduction

Properties and uses

Production of elemental carbon.

• Structure of carbon allotropes
• Nuclear properties

Our editors will review what you’ve submitted and determine whether to revise the article.

• Live Science - Carbon: Facts about an element that is a key ingredient for life on Earth
• Purdue University - Chemical Education Division Groups - The Inorganic Chemistry of Carbon
• National Center for Biotechnology Information - PubChem - Carbon
• Jefferson Lab - Carbon
• Lenntech - Carbon - C
• Chemistry LibreTexts - Carbon and Fireworks
• Khan Academy - Carbon and hydrocarbons
• Royal Society of Chemistry - Carbon
• Chemicool - Carbon
• University of Hawaiʻi Pressbooks - Carbon
• carbon - Children's Encyclopedia (Ages 8-11)
• carbon - Student Encyclopedia (Ages 11 and up)
• Table Of Contents

carbon (C) , nonmetallic chemical element in Group 14 (IVa) of the periodic table . Although widely distributed in nature, carbon is not particularly plentiful—it makes up only about 0.025 percent of Earth’s crust—yet it forms more compounds than all the other elements combined . In 1961 the isotope carbon-12 was selected to replace oxygen as the standard relative to which the atomic weights of all the other elements are measured. Carbon-14 , which is radioactive , is the isotope used in radiocarbon dating and radiolabeling.

On a weight basis, carbon is 19th in order of elemental abundance in Earth’s crust, and there are estimated to be 3.5 times as many carbon atoms as silicon atoms in the universe . Only hydrogen , helium , oxygen , neon , and nitrogen are atomically more abundant in the cosmos than carbon. Carbon is the cosmic product of the “burning” of helium, in which three helium nuclei, atomic weight 4, fuse to produce a carbon nucleus, atomic weight 12.

In the crust of Earth, elemental carbon is a minor component. However, carbon compounds (i.e., carbonates of magnesium and calcium ) form common minerals (e.g., magnesite , dolomite , marble , or limestone ). Coral and the shells of oysters and clams are primarily calcium carbonate . Carbon is widely distributed as coal and in the organic compounds that constitute petroleum , natural gas , and all plant and animal tissue . A natural sequence of chemical reactions called the carbon cycle —involving conversion of atmospheric carbon dioxide to carbohydrates by photosynthesis in plants, the consumption of these carbohydrates by animals and oxidation of them through metabolism to produce carbon dioxide and other products, and the return of carbon dioxide to the atmosphere —is one of the most important of all biological processes.

Carbon as an element was discovered by the first person to handle charcoal from fire. Thus, together with sulfur , iron , tin , lead , copper , mercury , silver , and gold , carbon was one of the small group of elements well known in the ancient world. Modern carbon chemistry dates from the development of coals , petroleum , and natural gas as fuels and from the elucidation of synthetic organic chemistry , both substantially developed since the 1800s.

Elemental carbon exists in several forms, each of which has its own physical characteristics. Two of its well-defined forms, diamond and graphite , are crystalline in structure, but they differ in physical properties because the arrangements of the atoms in their structures are dissimilar. A third form, called fullerene , consists of a variety of molecules composed entirely of carbon. Spheroidal, closed-cage fullerenes are called buckerminsterfullerenes , or “buckyballs,” and cylindrical fullerenes are called nanotubes. A fourth form, called Q-carbon, is crystalline and magnetic. Yet another form, called amorphous carbon, has no crystalline structure. Other forms—such as carbon black , charcoal , lampblack , coal , and coke —are sometimes called amorphous, but X-ray examination has revealed that these substances do possess a low degree of crystallinity. Diamond and graphite occur naturally on Earth, and they also can be produced synthetically; they are chemically inert but do combine with oxygen at high temperatures , just as amorphous carbon does. Fullerene was serendipitously discovered in 1985 as a synthetic product in the course of laboratory experiments to simulate the chemistry in the atmosphere of giant stars . It was later found to occur naturally in tiny amounts on Earth and in meteorites . Q-carbon is also synthetic, but scientists have speculated that it could form within the hot environments of some planetary cores.

The word carbon probably derives from the Latin carbo , meaning variously “coal,” “charcoal,” “ember.” The term diamond , a corruption of the Greek word adamas , “the invincible,” aptly describes the permanence of this crystallized form of carbon, just as graphite , the name for the other crystal form of carbon, derived from the Greek verb graphein , “to write,” reflects its property of leaving a dark mark when rubbed on a surface. Before the discovery in 1779 that graphite when burned in air forms carbon dioxide, graphite was confused with both the metal lead and a superficially similar substance, the mineral molybdenite.

Pure diamond is the hardest naturally occurring substance known and is a poor conductor of electricity . Graphite, on the other hand, is a soft slippery solid that is a good conductor of both heat and electricity. Carbon as diamond is the most expensive and brilliant of all the natural gemstones and the hardest of the naturally occurring abrasives. Graphite is used as a lubricant. In microcrystalline and nearly amorphous form, it is used as a black pigment , as an adsorbent, as a fuel, as a filler for rubber , and, mixed with clay , as the “lead” of pencils . Because it conducts electricity but does not melt, graphite is also used for electrodes in electric furnaces and dry cells as well as for making crucibles in which metals are melted. Molecules of fullerene show promise in a range of applications, including high-tensile-strength materials, unique electronic and energy-storage devices, and safe encapsulation of flammable gases, such as hydrogen . Q-carbon , which is created by rapidly cooling a sample of elemental carbon whose temperature has been raised to 4,000 K (3,727 °C [6,740 °F]), is harder than diamond, and it can be used to manufacture diamond structures (such as diamond films and microneedles) within its matrix. Elemental carbon is nontoxic.

Each of the “amorphous” forms of carbon has its own specific character, and, hence, each has its own particular applications. All are products of oxidation and other forms of decomposition of organic compounds. Coal and coke, for example, are used extensively as fuels. Charcoal is used as an absorptive and filtering agent and as a fuel and was once widely used as an ingredient in gunpowder . (Coals are elemental carbon mixed with varying amounts of carbon compounds. Coke and charcoal are nearly pure carbon.) In addition to its uses in making inks and paints , carbon black is added to the rubber used in tires to improve its wearing qualities. Bone black , or animal charcoal, can adsorb gases and colouring matter from many other materials.

Carbon, either elemental or combined, is usually determined quantitatively by conversion to carbon dioxide gas, which can then be absorbed by other chemicals to give either a weighable product or a solution with acidic properties that can be titrated.

Until 1955 all diamonds were obtained from natural deposits, most significant in southern Africa but occurring also in Brazil , Venezuela , Guyana , and Siberia . The single known source in the United States , in Arkansas , has no commercial importance; nor is India , once a source of fine diamonds, a significant present-day supplier. The primary source of diamonds is a soft bluish peridotic rock called kimberlite (after the famous deposit at Kimberley, South Africa ), found in volcanic structures called pipes, but many diamonds occur in alluvial deposits presumably resulting from the weathering of primary sources. Isolated finds around the world in regions where no sources are indicated have not been uncommon.

Natural deposits are worked by crushing, by gravity and flotation separations, and by removal of diamonds by their adherence to a layer of grease on a suitable table. The following products result: (1) diamond proper—distorted cubic crystalline gem-quality stones varying from colourless to red, pink, blue, green, or yellow; (2) bort—minute dark crystals of abrasive but not gem quality; (3) ballas—randomly oriented crystals of abrasive quality; (4) macles—triangular pillow-shaped crystals that are industrially useful; and (5) carbonado—mixed diamond–graphite crystallites containing other impurities.

The successful laboratory conversion of graphite to diamond was made in 1955. The procedure involved the simultaneous use of extremely high pressure and temperature with iron as a solvent or catalyst . Subsequently, chromium , manganese , cobalt , nickel , and tantalum were substituted for iron . Synthetic diamonds are now manufactured in several countries and are being used increasingly in place of natural materials as industrial abrasives .

Graphite occurs naturally in many areas, the deposits of major importance being in China , India, Brazil, Turkey, Mexico , Canada , Russia , and Madagascar. Both surface- and deep-mining techniques are used, followed by flotation , but the major portion of commercial graphite is produced by heating petroleum coke in an electric furnace . A better crystallized form, known as pyrolytic graphite, is obtained from the decomposition of low-molecular-weight hydrocarbons by heat. Graphite fibres of considerable tensile strength are obtained by carbonizing natural and synthetic organic fibres.

Carbon products are obtained by heating coal (to give coke), natural gas (to give blacks), or carbonaceous material of vegetable or animal origin, such as wood or bone (to give charcoal), at elevated temperatures in the presence of insufficient oxygen to allow combustion . The volatile by-products are recovered and used separately.

Nachweis von Kohlenstoffdioxid

Mit dem Nachweis von Kohlenstoffdioxid prüfst du, ob sich in deiner Probe Kohlenstoffdioxid befindet. Wie du genau vorgehst und was du beachten musst, zeigen wir dir hier und in unserem Video !

Wie weist du Kohlenstoffdioxid nach?

Nachweis von kohlenstoffdioxid: versuchsaufbau , nachweis kohlenstoffdioxid: durchführung, nachweis kohlenstoffdioxid: versuchsbeobachtung , nachweis kohlenstoffdioxid: versuchsauswertung und reaktionsgleichung, barytwasserprobe , glimmspanprobe.

Du weist Kohlenstoffdioxid in deiner Probe nach, indem du eine Nachweisreaktion durchführst. Der wichtigste Nachweis dafür ist die sogenannte Kalkwasserprobe . Daneben gibt es noch die Barytwasserprobe .

Beide Versuche beruhen auf einem sehr ähnlichen Prinzip : Du stellst die Kalkwasser- oder Barytwasserlösung  her und führst dort das zu untersuchende Gas ein. Wenn Kohlenstoffdioxid in deiner Probe vorhanden ist, erkennst du das deutlich an einer Trübung deiner Lösung. Ist kein Kohlenstoffdioxid vorhanden, verändert sich das Aussehen der Lösung nicht.

Die beiden Nachweisreaktionen helfen dir dabei herauszufinden, ob Kohlenstoffdioxid in deiner Probe enthalten ist. Du erfährst durch sie aber nicht, wie viel Kohlenstoffdioxid sich darin befindet. Deswegen zählen die Reaktionen in der Chemie auch zu den qualitativen Nachweisen .

Der Versuchsaufbau für den Nachweis von Kohlenstoffdioxid (CO 2 ) gestaltet sich einfach. Du brauchst nur ein Glas mit dem hergestellten Kalkwasser und ein Röhrchen, wie zum Beispiel einen Strohhalm. Mit dem Röhrchen kannst du deine Probe in die Lösung einführen.

Wenn du beispielsweise deine Atemluft auf Kohlenstoffdioxid testen willst, pustest du einfach vorsichtig für ein paar Sekunden durch das Röhrchen in das Kalkwasser. Du kannst aber auch jedes andere Gas auf Kohlenstoffdioxid testen und in die Lösung einführen.

Merke: Im Labor und im Umgang mit Chemikalien solltest du immer für deine Sicherheit sorgen. Denke also daran, vor dem Experimentieren deine Schutzbrille, Handschuhe und deinen Laborkittel anzuziehen.

Um Kohlenstoffdioxid mit der Kalkwasserprobe nachzuweisen, benötigst du eine Lösung von Calciumhydroxid . Die nennst du auch Kalkwasser . Dafür löst du Calciumhydroxid oder Calciumoxid in Wasser auf. Da beide Substanzen in Wasser schwer löslich sind, wird sich nicht alles davon auflösen. Deswegen musst du die Lösung noch umrühren und filtern, sodass jeweils nur noch das klare Kalkwasser übrig bleibt.

Die Lösung solltest du am besten frisch ansetzen . Denn auch in der Umgebungsluft ist Kohlenstoffdioxid enthalten, das nach einiger Zeit mit deiner angesetzten Lösung reagiert. Das würde deinen Nachweis von Kohlenstoffdioxid verfälschen.

Besonders bei der Barytwasserprobe solltest du deine angesetzte Lösung luftdicht verschließen, da die Nachweisreaktion noch etwas empfindlicher ist als die Kalkwasserprobe und schnell mit der Umgebungsluft reagiert.

Was passiert jetzt, nachdem du deine Probe in die Kalkwasserlösung eingeführt hast? Du kannst dann eine von zwei Beobachtungen machen:

• Der Test ist positiv : Die Kalkwasserlösung trübt sich weiß . Es ist Kohlenstoffdioxid in deiner Probe enthalten.
• Der Test ist negativ : Die Kalkwasserlösung verändert sich in ihrem Aussehen nicht . Das heißt, dass kein Kohlenstoffdioxid in deiner Probe nachweisbar ist.

Fällt die Nachweisreaktion von Kohlenstoffdioxid mit einer Trübung der Lösung positiv aus, enthält deine Lösung Kohlenstoffdioxid.

Die Trübung kannst du mit der Reaktionsgleichung der Kalkwasserprobe erklären:

Ca(OH) 2 + CO 2 → CaCO 3 ↓ + H 2 O 

Wenn Kohlenstoffdioxid in deiner Probe enthalten ist, reagiert die Calciumhydroxidlösung damit zum schwerlöslichen Calciumcarbonat . Der Pfeil nach unten   bedeutet, dass der Stoff ausfällt. Das heißt, dass er einen sogenannten Niederschlag bildet und in dem Fall deine Lösung weiß trübt. Als Nebenprodukt entsteht außerdem Wasser .

Um Kohlenstoffdioxid in deiner Probe nachzuweisen, führst du eine Nachweisreaktion mit einer Calciumhydroxidlösung  (Kalkwasser) durch. Der Test fällt positiv aus, wenn sich die zuvor klare Lösung weiß trübt. Das passiert durch die Bildung von schwerlöslichem Calciumcarbonat.

Als alternative Nachweisreaktion für Kohlenstoffdioxid kannst du die Barytwasserprobe durchführen. Das Prinzip der Nachweismethode ist sehr ähnlich zu dem der Kalkwasserprobe. 

Deine Lösung besteht dann allerdings nicht aus Calciumhydroxid in Wasser, sondern aus Bariumhydroxid in Wasser. Deswegen entsteht hier auch das schwer lösliche Bariumcarbonat , sobald es mit Kohlenstoffdioxid reagiert. Hier trübt sich deine zuvor klare Lösung ebenfalls und es entsteht als Nebenprodukt Wasser .  

Ba(OH) 2 + CO 2 → BaCO 3 ↓ + H 2 O

Neben Kohlenstoffdioxid ist auch Sauerstoff ein Gas, das häufig in chemischen Reaktionen entsteht. Wie du das Molekül in einem einfachen Versuch nachweist, erfährst du hier in unserem Video zur Glimmspanprobe !  

Beliebte Inhalte aus dem Bereich Anorganische Chemie

• Biuret-Reaktion Dauer: 04:45
• Ostwald Verfahren Dauer: 04:23
• Haber Bosch Verfahren Dauer: 04:53

Weitere Inhalte: Anorganische Chemie

Hallo, leider nutzt du einen AdBlocker.

Auf Studyflix bieten wir dir kostenlos hochwertige Bildung an. Dies können wir nur durch die Unterstützung unserer Werbepartner tun.

Schalte bitte deinen Adblocker für Studyflix aus oder füge uns zu deinen Ausnahmen hinzu. Das tut dir nicht weh und hilft uns weiter.

Danke! Dein Studyflix-Team

Wenn du nicht weißt, wie du deinen Adblocker deaktivierst oder Studyflix zu den Ausnahmen hinzufügst, findest du hier eine kurze Anleitung . Bitte lade anschließend die Seite neu .

• school Campus Bookshelves
• menu_book Bookshelves
• perm_media Learning Objects
• login Login
• how_to_reg Request Instructor Account
• hub Instructor Commons

Margin Size

• Download Page (PDF)
• Download Full Book (PDF)
• Periodic Table
• Physics Constants
• Scientific Calculator
• Reference & Cite
• Tools expand_more
• Readability

selected template will load here

This action is not available.

Experiment 7: Calorimetry

• Last updated
• Save as PDF
• Page ID 157956

\( \newcommand{\vecs}[1]{\overset { \scriptstyle \rightharpoonup} {\mathbf{#1}} } \)

\( \newcommand{\vecd}[1]{\overset{-\!-\!\rightharpoonup}{\vphantom{a}\smash {#1}}} \)

\( \newcommand{\id}{\mathrm{id}}\) \( \newcommand{\Span}{\mathrm{span}}\)

( \newcommand{\kernel}{\mathrm{null}\,}\) \( \newcommand{\range}{\mathrm{range}\,}\)

\( \newcommand{\RealPart}{\mathrm{Re}}\) \( \newcommand{\ImaginaryPart}{\mathrm{Im}}\)

\( \newcommand{\Argument}{\mathrm{Arg}}\) \( \newcommand{\norm}[1]{\| #1 \|}\)

\( \newcommand{\inner}[2]{\langle #1, #2 \rangle}\)

\( \newcommand{\Span}{\mathrm{span}}\)

\( \newcommand{\id}{\mathrm{id}}\)

\( \newcommand{\kernel}{\mathrm{null}\,}\)

\( \newcommand{\range}{\mathrm{range}\,}\)

\( \newcommand{\RealPart}{\mathrm{Re}}\)

\( \newcommand{\ImaginaryPart}{\mathrm{Im}}\)

\( \newcommand{\Argument}{\mathrm{Arg}}\)

\( \newcommand{\norm}[1]{\| #1 \|}\)

\( \newcommand{\Span}{\mathrm{span}}\) \( \newcommand{\AA}{\unicode[.8,0]{x212B}}\)

\( \newcommand{\vectorA}[1]{\vec{#1}}      % arrow\)

\( \newcommand{\vectorAt}[1]{\vec{\text{#1}}}      % arrow\)

\( \newcommand{\vectorB}[1]{\overset { \scriptstyle \rightharpoonup} {\mathbf{#1}} } \)

\( \newcommand{\vectorC}[1]{\textbf{#1}} \)

\( \newcommand{\vectorD}[1]{\overrightarrow{#1}} \)

\( \newcommand{\vectorDt}[1]{\overrightarrow{\text{#1}}} \)

\( \newcommand{\vectE}[1]{\overset{-\!-\!\rightharpoonup}{\vphantom{a}\smash{\mathbf {#1}}}} \)

EXPERIMENT 7:  DETERMINATION OF THE SPECIFIC HEAT OF A METAL

Lansing Community College General Chemistry Laboratory I

LEARNING OBJECTIVE

Determine the specific heat capacity of a metal using a coffee cup calorimeter.

INTRODUCTION

Heat is a form of energy that is transferred between objects with different temperatures. Heat always flows from high temperature to low temperature. The amount of heat absorbed or released (q) by the object depends on its mass (m), specific heat (C s ) , and the change in temperature (ΔT).

Specific heat can be defined as the amount of heat required (q) to raise the temperature of one gram of the substance by one degree Celsius.

                                                                                                                                                                                                              Equation 1

Rearranging Equation 1 :                                                                                                                                                   Equation 2

Each pure substance has a specific heat that is a characteristic physical property of that substance. The specific heats of some common substances are provided in Table 1 .

Table 1. Specific Heat of Some Common Substances

The magnitude of specific heat varies greatly from large values like that of water (4.184 J/g°•C) to small values like that of mercury (0.14 J/g°•C). When equal masses of objects are heated to absorb an equal amount of heat, the object with smaller the specific heat value would cause the greatest increase in temperature.

Heat energy is either absorbed or evolved during nearly all chemical and physical changes. If heat is absorbed or enters the system, the process is endothermic and if heat is evolved or exits the system, the process is exothermic . In the laboratory, heat flow is measured in an apparatus called a calorimeter. A calorimeter is a device used to determine heat flow during a chemical or physical change. A doubled Styrofoam cup fitted with a cover in which a hole is bored to accommodate a thermometer can serve well as a calorimeter (See Figure 7.1.)

Figure 7.1 Coffee Cup Calorimeter

In this experiment you will heat a known mass of a metal to a known temperature and then transfer it to a calorimeter that contains a known amount of room temperature water (T c ). The maximum temperature reached by the water in the calorimeter (T max ) will be recorded and the temperature change of the water (T max - T c ) and the temperature change of the metal (100.0°C - T max ) calculated.

The flow of energy (heat) between a metal and its environment is described by Equations 3 and 4 .

|q lost by metal |= q gained by water + q gained by calorimeter                                                                                                                                                 Equation 3

m metal x C smetal  x |T max – 100.0°C| = [m water x C swater   x (T max – T c )] + [15.9  x  (T max – T c )]

 (Note: heat capacity of coffee cup is calorimeter = 15.9 J/°C)

Rearranging Equation 4 to solve for the specific heat of the metal:

C smetal =                       Equation 5

EXPERIMENTAL PROCEDURE       

This experiment is done in a team of two. Place 200 mL of room temperature water from a carboy in a 250 mL beaker and set it aside for later use. Next place about 250 mL of tap water into a 400 mL beaker. Add 4-5 boiling chips into the tap water to prevent bumping. Bring the tap water to a gentle boil using a hot plate.  Obtain three clean dry 18 by 175 mm test tubes. Label them runs 1 – 3. Tare one of the test tubes in a beaker. Carefully add about 30 g of the metal sample to the test tube and record the mass of the metal in DATA TABLE I . While you are at the balance, mass two additional samples into the test tubes 2, and 3. Put all the three test tubes containing the unknown metal in the water bath. Heat to boiling, and then maintain the temperature for about 5 minutes. Assume that the temperature of the metal is 100.0°C after it has been in the boiling water bath for at least 5 minutes.

While the metal is being heated, obtain two Styrofoam cups, a lid, a thermometer and a timer. Using a graduated cylinder, measure 50.0 mL of the room temperature water and transfer into the double Styrofoam cup. Allow 5 minutes for this system to reach thermal equilibrium.  After 5 minutes, record the temperature of the water, T c , in DATA TABLE I and in DATA TABLE II for time 0 seconds.

Using a test tube holder, lift the test tube containing the heated metal from the boiling water bath. Quickly remove the lid and pour the hot metal (labeled run 1) into the calorimeter. Make sure no hot water from the outside of the test tube drips into the calorimeter. Replace the lid of the calorimeter and the thermometer. Swirl the system gently. Record the temperature every 5 seconds for a minute and then every 15 seconds for about 2-3 minutes or until you observe a maximum temperature ( T max ) for about four consecutive readings. Continue to swirl the calorimeter gently while recording temperatures. Drain the metal and water into a large filter funnel in the hood. Repeat the above procedure using two additional samples. Dry the calorimeter between each trial.

Plot time (x- axis) vs. temperature time for each of the three runs using Excel . Please combine all three runs on one graph. Column A is time and columns B, C, and D will be temperatures for Runs 1-3. Give the graph a title and label the x and y axes. Determine the T max from the graph and label it on the graph by inserting a double headed arrow shape Figure 7.2.

Finally, calculate the specific heat of the metal using Equation 5.

Clean Up & Waste Disposal

• Pour the metal sample and warm water into the labeled bottles fitted with funnels in the hood.
• Wash the test tubes and place them in the tray next to the oven.
• Please turn off the digital thermometers, and the timer. Return them to the side bench.
• Shut down the laptop computer and return it to its numbered space in the Dry-Dock. Plug in the correct laptop charging cable.
• Carefully unplug the hot plate and leave it out on the bench.
• Please clean the bench top with a moist paper towel

CALCULATIONS

• Determine the change in temperature, T max – T c for water.

T c = Temperature of the cold water in the coffee cup before the metal was dropped

T max = Final temperature of the water after the metal was dropped into the coffee cup

• Determine the absolute value for the change in temperature of the metal, |T Max – 100.0°C|.
• Use Equation 5 to calculate the specific heat capacity of the unknown metal.

Cs metal =                  Equation 5

 = mass of water in grams

 = mass of metal in grams

DATA SHEET FOR EXPERIMENT 7 – DETERMINATION OF THE SPECIFIC HEAT OF A METAL

 Your Name: ______________________      Lab Partner Name: _______________________

DATA TABLE I (2 pts.)

(Record the measurements with units and the correct number of significant figures.)

DATA TABLE II (2 pts.)

Plot time (x-axis) vs. temperature for each of the three runs in DATA TABLE II using Excel. Give each graph a title and label the x and y axes.  Mark the ∆T’s (T max – T c ) on your graph. (2 pts.)

TABLE III – Tabulated Results (2 pts.)

Calculations: Show your calculations below. Be sure to include units in your set up and report your answer to the correct number of significant figures.

• Calculated Specific heat for Run 1: (2 pts.)
• Average Specific heat: (1 pt.)
• Average deviation: (2 pts.)
• Relative % error for average specific heat: (1 pt.)

POST LABORATORY for EXPERIMENT 7 - DETERMINATION of the SPECIFIC HEAT of a METAL

Name: _________________________________________

• Discuss the precision and accuracy of your specific heat determination. Use your calculated average deviation and relative error in your discussion. (An average deviation of 0.02 J/g°C and a relative error of less than 10% are considered good in this experiment.) (4 pts.)
• Explain clearly how the two errors below would increase or decrease your calculated value for specific heat by referring to the equation:

Error #1:  The student used 25.372 g for this experiment but recorded 23.372 g in the data table and used the incorrect value when calculating the specific heat. (Hint:  the error is using the 23.372 g data point.) (2 pts.)

Error #2:  The initial temperature of the metal was 98 °C, not 100 °C, as we have assumed.  (Hint:  The error is using the 100 °C.) (2 pts.)

• EO Explorer

• Global Maps

The Carbon Cycle

Carbon is the backbone of life on Earth. We are made of carbon, we eat carbon, and our civilizations—our economies, our homes, our means of transport—are built on carbon. We need carbon, but that need is also entwined with one of the most serious problems facing us today: global climate change.

Carbon is both the foundation of all life on Earth, and the source of the majority of energy consumed by human civilization. [Photographs ©2007 MorBCN (top) and ©2009 sarahluv (lower).]

Forged in the heart of aging stars, carbon is the fourth most abundant element in the Universe. Most of Earth’s carbon—about 65,500 billion metric tons—is stored in rocks. The rest is in the ocean, atmosphere, plants, soil, and fossil fuels.

Carbon flows between each reservoir in an exchange called the carbon cycle, which has slow and fast components. Any change in the cycle that shifts carbon out of one reservoir puts more carbon in the other reservoirs. Changes that put carbon gases into the atmosphere result in warmer temperatures on Earth.

This diagram of the fast carbon cycle shows the movement of carbon between land, atmosphere, and oceans. Yellow numbers are natural fluxes, and red are human contributions in gigatons of carbon per year. White numbers indicate stored carbon. ( Diagram adapted from U.S. DOE, Biological and Environmental Research Information System. )

Over the long term, the carbon cycle seems to maintain a balance that prevents all of Earth’s carbon from entering the atmosphere (as is the case on Venus) or from being stored entirely in rocks. This balance helps keep Earth’s temperature relatively stable, like a thermostat.

This thermostat works over a few hundred thousand years, as part of the slow carbon cycle. This means that for shorter time periods—tens to a hundred thousand years—the temperature of Earth can vary. And, in fact, Earth swings between ice ages and warmer interglacial periods on these time scales. Parts of the carbon cycle may even amplify these short-term temperature changes.

The uplift of the Himalaya, beginning 50 million years ago, reset Earth’s thermostat by providing a large source of fresh rock to pull more carbon into the slow carbon cycle through chemical weathering. The resulting drop in temperatures and the formation of ice sheets changed the ratio between heavy and light oxygen in the deep ocean, as shown in this graph. (Graph based on data from Zachos at al., 2001.)

On very long time scales (millions to tens of millions of years), the movement of tectonic plates and changes in the rate at which carbon seeps from the Earth’s interior may change the temperature on the thermostat. Earth has undergone such a change over the last 50 million years, from the extremely warm climates of the Cretaceous (roughly 145 to 65 million years ago) to the glacial climates of the Pleistocene (roughly 1.8 million to 11,500 years ago). [See Divisions of Geologic Time—Major Chronostratigraphic and Geochronologic Units for more information about geological eras.]

The Slow Carbon Cycle

Through a series of chemical reactions and tectonic activity, carbon takes between 100-200 million years to move between rocks, soil, ocean, and atmosphere in the slow carbon cycle. On average, 10 13 to 10 14 grams (10–100 million metric tons) of carbon move through the slow carbon cycle every year. In comparison, human emissions of carbon to the atmosphere are on the order of 10 15 grams, whereas the fast carbon cycle moves 10 16 to 10 17 grams of carbon per year.

The movement of carbon from the atmosphere to the lithosphere (rocks) begins with rain. Atmospheric carbon combines with water to form a weak acid—carbonic acid—that falls to the surface in rain. The acid dissolves rocks—a process called chemical weathering—and releases calcium, magnesium, potassium, or sodium ions. Rivers carry the ions to the ocean.

Rivers carry calcium ions—the result of chemical weathering of rocks—into the ocean, where they react with carbonate dissolved in the water. The product of that reaction, calcium carbonate, is then deposited onto the ocean floor, where it becomes limestone. ( Photograph ©2009 Greg Carley. )

In the ocean, the calcium ions combine with bicarbonate ions to form calcium carbonate, the active ingredient in antacids and the chalky white substance that dries on your faucet if you live in an area with hard water. In the modern ocean, most of the calcium carbonate is made by shell-building (calcifying) organisms (such as corals) and plankton (like coccolithophores and foraminifera). After the organisms die, they sink to the seafloor. Over time, layers of shells and sediment are cemented together and turn to rock, storing the carbon in stone—limestone and its derivatives.

Limestone, or its metamorphic cousin, marble, is rock made primarily of calcium carbonate. These rock types are often formed from the bodies of marine plants and animals, and their shells and skeletons can be preserved as fossils. Carbon locked up in limestone can be stored for millions—or even hundreds of millions—of years. ( Photograph ©2008 Rookuzz (Hmm). )

Only 80 percent of carbon-containing rock is currently made this way. The remaining 20 percent contain carbon from living things (organic carbon) that have been embedded in layers of mud. Heat and pressure compress the mud and carbon over millions of years, forming sedimentary rock such as shale. In special cases, when dead plant matter builds up faster than it can decay, layers of organic carbon become oil, coal, or natural gas instead of sedimentary rock like shale.

This coal seam in Scotland was originally a layer of sediment, rich in organic carbon. The sedimentary layer was eventually buried deep underground, and the heat and pressure transformed it into coal. Coal and other fossil fuels are a convenient source of energy, but when they are burned, the stored carbon is released into the atmosphere. This alters the balance of the carbon cycle, and is changing Earth’s climate. ( Photograph ©2010 Sandchem. )

The slow cycle returns carbon to the atmosphere through volcanoes. Earth’s land and ocean surfaces sit on several moving crustal plates. When the plates collide, one sinks beneath the other, and the rock it carries melts under the extreme heat and pressure. The heated rock recombines into silicate minerals, releasing carbon dioxide.

When volcanoes erupt, they vent the gas to the atmosphere and cover the land with fresh silicate rock to begin the cycle again. At present, volcanoes emit between 130 and 380 million metric tons of carbon dioxide per year. For comparison, humans emit about 30 billion tons of carbon dioxide per year—100–300 times more than volcanoes—by burning fossil fuels.

Chemistry regulates this dance between ocean, land, and atmosphere. If carbon dioxide rises in the atmosphere because of an increase in volcanic activity, for example, temperatures rise, leading to more rain, which dissolves more rock, creating more ions that will eventually deposit more carbon on the ocean floor. It takes a few hundred thousand years to rebalance the slow carbon cycle through chemical weathering.

Carbon stored in rocks is naturally returned to the atmosphere by volcanoes. In this photograph, Russia’s Kizimen Volcano vents ash and volcanic gases in January 2011. Kizimen is located on the Kamchatka Peninsula, where the Pacific Plate is subducting beneath Asia. (Photograph ©2011 Artyom Bezotechestvo/ Photo Kamchatka. )

However, the slow carbon cycle also contains a slightly faster component: the ocean. At the surface, where air meets water, carbon dioxide gas dissolves in and ventilates out of the ocean in a steady exchange with the atmosphere. Once in the ocean, carbon dioxide gas reacts with water molecules to release hydrogen, making the ocean more acidic. The hydrogen reacts with carbonate from rock weathering to produce bicarbonate ions.

Before the industrial age, the ocean vented carbon dioxide to the atmosphere in balance with the carbon the ocean received during rock weathering. However, since carbon concentrations in the atmosphere have increased, the ocean now takes more carbon from the atmosphere than it releases. Over millennia, the ocean will absorb up to 85 percent of the extra carbon people have put into the atmosphere by burning fossil fuels, but the process is slow because it is tied to the movement of water from the ocean’s surface to its depths.

In the meantime, winds, currents, and temperature control the rate at which the ocean takes carbon dioxide from the atmosphere. (See The Ocean’s Carbon Balance on the Earth Observatory.) It is likely that changes in ocean temperatures and currents helped remove carbon from and then restore carbon to the atmosphere over the few thousand years in which the ice ages began and ended.

The Fast Carbon Cycle

The time it takes carbon to move through the fast carbon cycle is measured in a lifespan. The fast carbon cycle is largely the movement of carbon through life forms on Earth, or the biosphere. Between 10 15 and 10 17 grams (1,000 to 100,000 million metric tons) of carbon move through the fast carbon cycle every year.

Carbon plays an essential role in biology because of its ability to form many bonds—up to four per atom—in a seemingly endless variety of complex organic molecules. Many organic molecules contain carbon atoms that have formed strong bonds to other carbon atoms, combining into long chains and rings. Such carbon chains and rings are the basis of living cells. For instance, DNA is made of two intertwined molecules built around a carbon chain.

The bonds in the long carbon chains contain a lot of energy. When the chains break apart, the stored energy is released. This energy makes carbon molecules an excellent source of fuel for all living things.

During photosynthesis, plants absorb carbon dioxide and sunlight to create fuel—glucose and other sugars—for building plant structures. This process forms the foundation of the fast (biological) carbon cycle. (Illustration adapted from P.J. Sellers et al., 1992.)

Plants and phytoplankton are the main components of the fast carbon cycle. Phytoplankton (microscopic organisms in the ocean) and plants take carbon dioxide from the atmosphere by absorbing it into their cells. Using energy from the Sun, both plants and plankton combine carbon dioxide (CO 2 ) and water to form sugar (CH 2 O) and oxygen. The chemical reaction looks like this:

CO 2 + H 2 O + energy = CH 2 O + O 2

Four things can happen to move carbon from a plant and return it to the atmosphere, but all involve the same chemical reaction. Plants break down the sugar to get the energy they need to grow. Animals (including people) eat the plants or plankton, and break down the plant sugar to get energy. Plants and plankton die and decay (are eaten by bacteria) at the end of the growing season. Or fire consumes plants. In each case, oxygen combines with sugar to release water, carbon dioxide, and energy. The basic chemical reaction looks like this:

CH 2 O + O 2 = CO 2 + H 2 O + energy

In all four processes, the carbon dioxide released in the reaction usually ends up in the atmosphere. The fast carbon cycle is so tightly tied to plant life that the growing season can be seen by the way carbon dioxide fluctuates in the atmosphere. In the Northern Hemisphere winter, when few land plants are growing and many are decaying, atmospheric carbon dioxide concentrations climb. During the spring, when plants begin growing again, concentrations drop. It is as if the Earth is breathing.

The ebb and flow of the fast carbon cycle is visible in the changing seasons. As the large land masses of Northern Hemisphere green in the spring and summer, they draw carbon out of the atmosphere. This graph shows the difference in carbon dioxide levels from the previous month, with the long-term trend removed.

This cycle peaks in August, with about 2 parts per million of carbon dioxide drawn out of the atmosphere. In the fall and winter, as vegetation dies back in the northern hemisphere, decomposition and respiration returns carbon dioxide to the atmosphere.

(Graph by Marit Jentoft-Nilsen and Robert Simmon, using data from the NOAA Earth System Research Laboratory. Maps by Robert Simmon and Reto Stöckli, using MODIS data.)

Changes in the Carbon Cycle

Left unperturbed, the fast and slow carbon cycles maintain a relatively steady concentration of carbon in the atmosphere, land, plants, and ocean. But when anything changes the amount of carbon in one reservoir, the effect ripples through the others.

In Earth’s past, the carbon cycle has changed in response to climate change. Variations in Earth’s orbit alter the amount of energy Earth receives from the Sun and leads to a cycle of ice ages and warm periods like Earth’s current climate. (See Milutin Milankovitch. ) Ice ages developed when Northern Hemisphere summers cooled and ice built up on land, which in turn slowed the carbon cycle. Meanwhile, a number of factors including cooler temperatures and increased phytoplankton growth may have increased the amount of carbon the ocean took out of the atmosphere. The drop in atmospheric carbon caused additional cooling. Similarly, at the end of the last Ice Age, 10,000 years ago, carbon dioxide in the atmosphere rose dramatically as temperatures warmed.

Levels of carbon dioxide in the atmosphere have corresponded closely with temperature over the past 800,000 years. Although the temperature changes were touched off by variations in Earth’s orbit, the increased global temperatures released CO 2 into the atmosphere, which in turn warmed the Earth. Antarctic ice-core data show the long-term correlation until about 1900. (Graphs by Robert Simmon, using data from Lüthi et al., 2008, and Jouzel et al., 2007. )

Shifts in Earth’s orbit are happening constantly, in predictable cycles. In about 30,000 years, Earth’s orbit will have changed enough to reduce sunlight in the Northern Hemisphere to the levels that led to the last ice age.

Today, changes in the carbon cycle are happening because of people. We perturb the carbon cycle by burning fossil fuels and clearing land.

When we clear forests, we remove a dense growth of plants that had stored carbon in wood, stems, and leaves—biomass. By removing a forest, we eliminate plants that would otherwise take carbon out of the atmosphere as they grow. We tend to replace the dense growth with crops or pasture, which store less carbon. We also expose soil that vents carbon from decayed plant matter into the atmosphere. Humans are currently emitting just under a billion tons of carbon into the atmosphere per year through land use changes.

The burning of fossil fuels is the primary source of increased carbon dioxide in the atmosphere today. ( Photograph ©2009 stevendepolo.)

Without human interference, the carbon in fossil fuels would leak slowly into the atmosphere through volcanic activity over millions of years in the slow carbon cycle. By burning coal, oil, and natural gas, we accelerate the process, releasing vast amounts of carbon (carbon that took millions of years to accumulate) into the atmosphere every year. By doing so, we move the carbon from the slow cycle to the fast cycle. In 2009, humans released about 8.4 billion tons of carbon into the atmosphere by burning fossil fuel.

Emissions of carbon dioxide by humanity (primarily from the burning of fossil fuels, with a contribution from cement production) have been growing steadily since the onset of the industrial revolution. About half of these emissions are removed by the fast carbon cycle each year, the rest remain in the atmosphere. (Graph by Robert Simmon, using data from the Carbon Dioxide Information Analysis Center and Global Carbon Project. )

Since the beginning of the Industrial Revolution, when people first started burning fossil fuels, carbon dioxide concentrations in the atmosphere have risen from about 280 parts per million to 387 parts per million, a 39 percent increase. This means that for every million molecules in the atmosphere, 387 of them are now carbon dioxide—the highest concentration in two million years. Methane concentrations have risen from 715 parts per billion in 1750 to 1,774 parts per billion in 2005, the highest concentration in at least 650,000 years.

Effects of Changing the Carbon Cycle

All of this extra carbon needs to go somewhere. So far, land plants and the ocean have taken up about 55 percent of the extra carbon people have put into the atmosphere while about 45 percent has stayed in the atmosphere. Eventually, the land and oceans will take up most of the extra carbon dioxide, but as much as 20 percent may remain in the atmosphere for many thousands of years.

The changes in the carbon cycle impact each reservoir. Excess carbon in the atmosphere warms the planet and helps plants on land grow more. Excess carbon in the ocean makes the water more acidic, putting marine life in danger.

It is significant that so much carbon dioxide stays in the atmosphere because CO 2 is the most important gas for controlling Earth’s temperature. Carbon dioxide, methane, and halocarbons are greenhouse gases that absorb a wide range of energy—including infrared energy (heat) emitted by the Earth—and then re-emit it. The re-emitted energy travels out in all directions, but some returns to Earth, where it heats the surface. Without greenhouse gases, Earth would be a frozen -18 degrees Celsius (0 degrees Fahrenheit). With too many greenhouse gases, Earth would be like Venus, where the greenhouse atmosphere keeps temperatures around 400 degrees Celsius (750 Fahrenheit).

Rising concentrations of carbon dioxide are warming the atmosphere. The increased temperature results in higher evaporation rates and a wetter atmosphere, which leads to a vicious cycle of further warming. ( Photograph ©2011 Patrick Wilken. )

Because scientists know which wavelengths of energy each greenhouse gas absorbs, and the concentration of the gases in the atmosphere, they can calculate how much each gas contributes to warming the planet. Carbon dioxide causes about 20 percent of Earth’s greenhouse effect; water vapor accounts for about 50 percent; and clouds account for 25 percent. The rest is caused by small particles (aerosols) and minor greenhouse gases like methane.

Water vapor concentrations in the air are controlled by Earth’s temperature. Warmer temperatures evaporate more water from the oceans, expand air masses, and lead to higher humidity. Cooling causes water vapor to condense and fall out as rain, sleet, or snow.

Carbon dioxide, on the other hand, remains a gas at a wider range of atmospheric temperatures than water. Carbon dioxide molecules provide the initial greenhouse heating needed to maintain water vapor concentrations. When carbon dioxide concentrations drop, Earth cools, some water vapor falls out of the atmosphere, and the greenhouse warming caused by water vapor drops. Likewise, when carbon dioxide concentrations rise, air temperatures go up, and more water vapor evaporates into the atmosphere—which then amplifies greenhouse heating.

So while carbon dioxide contributes less to the overall greenhouse effect than water vapor, scientists have found that carbon dioxide is the gas that sets the temperature. Carbon dioxide controls the amount of water vapor in the atmosphere and thus the size of the greenhouse effect.

Rising carbon dioxide concentrations are already causing the planet to heat up. At the same time that greenhouse gases have been increasing, average global temperatures have risen 0.8 degrees Celsius (1.4 degrees Fahrenheit) since 1880.

With the seasonal cycle removed, the atmospheric carbon dioxide concentration measured at Mauna Loa Volcano, Hawaii, shows a steady increase since 1957. At the same time global average temperatures are rising as a result of heat trapped by the additional CO 2 and increased water vapor concentration. (Graphs by Robert Simmon, using CO 2 data from the NOAA Earth System Research Laboratory and temperature data from the Goddard Institute for Space Studies. )

This rise in temperature isn’t all the warming we will see based on current carbon dioxide concentrations. Greenhouse warming doesn’t happen right away because the ocean soaks up heat. This means that Earth’s temperature will increase at least another 0.6 degrees Celsius (1 degree Fahrenheit) because of carbon dioxide already in the atmosphere. The degree to which temperatures go up beyond that depends in part on how much more carbon humans release into the atmosphere in the future.

About 30 percent of the carbon dioxide that people have put into the atmosphere has diffused into the ocean through the direct chemical exchange. Dissolving carbon dioxide in the ocean creates carbonic acid, which increases the acidity of the water. Or rather, a slightly alkaline ocean becomes a little less alkaline. Since 1750, the pH of the ocean’s surface has dropped by 0.1, a 30 percent change in acidity.

Some of the excess CO 2 emitted by human activity dissolves in the ocean, becoming carbonic acid. Increases in carbon dioxide are not only leading to warmer oceans, but also to more acidic oceans. ( Photograph ©2010 Way Out West News. )

Ocean acidification affects marine organisms in two ways. First, carbonic acid reacts with carbonate ions in the water to form bicarbonate. However, those same carbonate ions are what shell-building animals like coral need to create calcium carbonate shells. With less carbonate available, the animals need to expend more energy to build their shells. As a result, the shells end up being thinner and more fragile.

Second, the more acidic water is, the better it dissolves calcium carbonate. In the long run, this reaction will allow the ocean to soak up excess carbon dioxide because more acidic water will dissolve more rock, release more carbonate ions, and increase the ocean’s capacity to absorb carbon dioxide. In the meantime, though, more acidic water will dissolve the carbonate shells of marine organisms, making them pitted and weak.

Warmer oceans—a product of the greenhouse effect—could also decrease the abundance of phytoplankton, which grow better in cool, nutrient-rich waters. This could limit the ocean’s ability to take carbon from the atmosphere through the fast carbon cycle.

On the other hand, carbon dioxide is essential for plant and phytoplankton growth. An increase in carbon dioxide could increase growth by fertilizing those few species of phytoplankton and ocean plants (like sea grasses) that take carbon dioxide directly from the water. However, most species are not helped by the increased availability of carbon dioxide.

Plants on land have taken up approximately 25 percent of the carbon dioxide that humans have put into the atmosphere. The amount of carbon that plants take up varies greatly from year to year, but in general, the world’s plants have increased the amount of carbon dioxide they absorb since 1960. Only some of this increase occurred as a direct result of fossil fuel emissions.

With more atmospheric carbon dioxide available to convert to plant matter in photosynthesis, plants were able to grow more. This increased growth is referred to as carbon fertilization. Models predict that plants might grow anywhere from 12 to 76 percent more if atmospheric carbon dioxide is doubled, as long as nothing else, like water shortages, limits their growth. However, scientists don’t know how much carbon dioxide is increasing plant growth in the real world, because plants need more than carbon dioxide to grow.

Plants also need water, sunlight, and nutrients, especially nitrogen. If a plant doesn’t have one of these things, it won’t grow regardless of how abundant the other necessities are. There is a limit to how much carbon plants can take out of the atmosphere, and that limit varies from region to region. So far, it appears that carbon dioxide fertilization increases plant growth until the plant reaches a limit in the amount of water or nitrogen available.

Some of the changes in carbon absorption are the result of land use decisions. Agriculture has become much more intensive, so we can grow more food on less land. In high and mid-latitudes, abandoned farmland is reverting to forest, and these forests store much more carbon, both in wood and soil, than crops would. In many places, we prevent plant carbon from entering the atmosphere by extinguishing wildfires. This allows woody material (which stores carbon) to build up. All of these land use decisions are helping plants absorb human-released carbon in the Northern Hemisphere.

Changes in land cover—forests converted to fields and fields converted to forests—have a corresponding effect on the carbon cycle. In some Northern Hemisphere countries, many farms were abandoned in the early 20th century and the land reverted to forest. As a result, carbon was drawn out of the atmosphere and stored in trees on land. ( Photograph ©2007 Husein Kadribegic. )

In the tropics, however, forests are being removed, often through fire, and this releases carbon dioxide. As of 2008, deforestation accounted for about 12 percent of all human carbon dioxide emissions.

The biggest changes in the land carbon cycle are likely to come because of climate change. Carbon dioxide increases temperatures, extending the growing season and increasing humidity. Both factors have led to some additional plant growth. However, warmer temperatures also stress plants. With a longer, warmer growing season, plants need more water to survive. Scientists are already seeing evidence that plants in the Northern Hemisphere slow their growth in the summer because of warm temperatures and water shortages.

Dry, water-stressed plants are also more susceptible to fire and insects when growing seasons become longer. In the far north, where an increase in temperature has the greatest impact, the forests have already started to burn more, releasing carbon from the plants and the soil into the atmosphere. Tropical forests may also be extremely susceptible to drying. With less water, tropical trees slow their growth and take up less carbon, or die and release their stored carbon to the atmosphere.

The warming caused by rising greenhouse gases may also “bake” the soil, accelerating the rate at which carbon seeps out in some places. This is of particular concern in the far north, where frozen soil—permafrost—is thawing. Permafrost contains rich deposits of carbon from plant matter that has accumulated for thousands of years because the cold slows decay. When the soil warms, the organic matter decays and carbon—in the form of methane and carbon dioxide—seeps into the atmosphere.

Current research estimates that permafrost in the Northern Hemisphere holds 1,672 billion tons (Petagrams) of organic carbon. If just 10 percent of this permafrost were to thaw, it could release enough extra carbon dioxide to the atmosphere to raise temperatures an additional 0.7 degrees Celsius (1.3 degrees Fahrenheit) by 2100.

Studying the Carbon Cycle

Many of the questions scientists still need to answer about the carbon cycle revolve around how it is changing. The atmosphere now contains more carbon than at any time in at least two million years. Each reservoir of the cycle will change as this carbon makes its way through the cycle.

What will those changes look like? What will happen to plants as temperatures increase and climate changes? Will they remove more carbon from the atmosphere than they put back? Will they become less productive? How much extra carbon will melting permafrost put into the atmosphere, and how much will that amplify warming? Will ocean circulation or warming change the rate at which the ocean takes up carbon? Will ocean life become less productive? How much will the ocean acidify, and what effects will that have?

Time series of satellite data, like the imagery available from the Landsat satellites, allow scientists to monitor changes in forest cover. Deforestation can release carbon dioxide into the atmosphere, while forest regrowth removes CO 2 . This pair of false-color images shows clear cutting and forest regrowth between 1984 and 2010 in Washington State, northeast of Mount Rainier. Dark green corresponds to mature forests, red indicates bare ground or dead plant material (freshly cut areas), and light green indicates relatively new growth. (NASA image by Robert Simmon, using Landsat data from the USGS Global Visualization Viewer. )

NASA’s role in answering these questions is to provide global satellite observations and related field observations. As of early 2011, two types of satellite instruments were collecting information relevant to the carbon cycle.

The Moderate Resolution Imaging Spectroradiometer (MODIS) instruments, flying on NASA’s Terra and Aqua satellites, measure the amount of carbon plants and phytoplankton turn into matter as they grow, a measurement called net primary productivity. The MODIS sensors also measure how many fires occur and where they burn.

Two Landsat satellites provide a detailed view of ocean reefs, what is growing on land, and how land cover is changing. It is possible to see the growth of a city or a transformation from forest to farm. This information is crucial because land use accounts for one-third of all human carbon emissions.

Future NASA satellites will continue these observations, and also measure carbon dioxide and methane in the atmosphere and vegetation height and structure.

All of these measurements will help us see how the global carbon cycle is changing through time. They will help us gauge the impact we are having on the carbon cycle by releasing carbon into the atmosphere or finding ways to store it elsewhere. They will show us how our changing climate is altering the carbon cycle, and how the changing carbon cycle is altering our climate.

Most of us, however, will observe changes in the carbon cycle in a more personal way. For us, the carbon cycle is the food we eat, the electricity in our homes, the gas in our cars, and the weather over our heads. We are a part of the carbon cycle, and so our decisions about how we live ripple across the cycle. Likewise, changes in the carbon cycle will impact the way we live. As each of us come to understand our role in the carbon cycle, the knowledge empowers us to control our personal impact and to understand the changes we are seeing in the world around us.

• Angert, A., Biraud, S., Bonfils, C., Henning, C.C., Buermann, W., Pinzon, J., Tucker, C.J., and Fung, I. (2005, August 2). Drier summers cancel out the CO2 uptake enhancement induced by warmer springs. Proceedings of the National Academy of Science, 102 (31), 10823-10827.
• Archer, D. (2008, May). Carbon cycle: Checking the thermostat. Nature Geoscience, 1, 289-290.
• Behrenfeld, M.J., et al. (2006, December 7). Climate-driven trends in contemporary ocean productivity. Nature, 444, 752-755.
• Berner, R.A. (2003, November 20). The long-term carbon cycle, fossil fuels and atmospheric composition. Nature, 426, 323-326.
• Bonan, G.B. (2008, June 13). Forests and climate change: Forcings, feedbacks, and the climate benefit of forests. Science, 320, 1444-1449.
• Campbell, N.A. and Reece, J.B. (2005). Biology. San Francisco: Pearson Benjamin Cummings. 7th ed.
• Denecke, E.J. (2002) Earth Science: The Physical Setting Hauppauge, New York: Barron’s Educational Series, Inc.
• Denman, K.L., Brasseur, G., Chidthaisong, A., Ciais, P., Cox, P.M., Dickinson, R.E., Hauglustaine, D., Heinze, C., Holland, E., Jacob, D., Lohmann, U., Ramachandran, S., da Silva Dias, P.L., Wofsy, S.C. and Zhang, X. (2007) Couplings Between Changes in the Climate System and Biogeochemistry. In: Climate Change 2007: The Physical Science Basis. Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change, [Solomon, S., D. Qin, M. Manning, Z. Chen, M. Marquis, K.B. Averyt, M.Tignor and H.L. Miller (eds.)]. Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA.
• Doney, S.C. (2006, March). The dangers of ocean acidification. Scientific American, 58-65.
• Emsley, J. (2001). Nature's Building Blocks. Oxford: Oxford University Press.
• Goetz, S.J., Bunn, A.G., Fiske, G.J., and Houghton, R.A. (2005, September 20). Satellite-observed photosynthetic trends across boreal North America associated with climate and fire disturbance. Proceedings of the National Academy of Sciences, 102 (38), 13521-13525.
• Global Carbon Project. (2010, November 21). Carbon budget 2009. Accessed May 4, 2011.
• Grosse, G., Romanovsky, V., Jorgenson, T., Anthony, K.W., Brown, J., and Overduin, P.P. (2011, March 1). Vulnerability and feedbacks of permafrost to climate change. EOS, 92 (9), 73-74.
• Hansen, J., Ruedy, R., Sato, M., and Lo, K. (2010, December 14). Global surface temperature change. Reviews of Geophysics, 48, RG4004.
• Hansen, J., Nazarenko, L., Ruedy, R., Sato, M., Willis, J., Del Genio, A., Koch, D., Lacis, A., Lo, K., Menon, S., Novakov, T., Perlwitz, J., Russel, G., Schmidt, G.A., and Tausnev, N. (2005, June 3). Earth’s energy imbalance: Confirmation and implications. Science, 308 (5727), 1431-1435.
• Hardt, M.J., and Safina, C. (2010, August). How acidification threatens oceans from the inside out. Scientific American.
• Intergovernmental Panel on Climate Change. (2007). Summary for Policymakers. In: Climate Change 2007: The Physical Science Basis. Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change, [Solomon, S., D. Qin, M. Manning, Z. Chen, M. Marquis, K.B. Averyt, M.Tignor and H.L. Miller (eds.)]. Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA.
• Jouzel, J., et al. (2007). EPICA Dome C Ice Core 800KYr Deuterium Data and Temperature Estimates. IGBP PAGES/World Data Center for Paleoclimatology Data Contribution Series #2007-091. NOAA/NCDC Paleoclimatology Program, Boulder CO, USA. Accessed June 13, 2010.
• Lacis, A.A., Schmidt, G.A., Rind, D., and Ruedy, R.A. (2010, October 15). Atmospheric CO2: Principal control governing Earth’s temperature. Science, 330 (6002), 356-359.
• Lacis, A. (2010, October). CO2: The thermostat that controls Earth’s temperature. NASA Goddard Institute for Space Studies. Accessed December 17, 2010.
• Le Quéré, C., Raupach, M.P., Canadell, J.G., Marland, G., et al. (2009, November 17). Trends in the sources and sinks of carbon dioxide. Nature Geoscience, 2, 831-836.
• Lüthi, D., M. Le Floch, B. Bereiter, T. Blunier, J.-M. Barnola, U. Siegenthaler, D. Raynaud, J. Jouzel, H. Fischer, K. Kawamura, and T.F. Stocker. (2008, May 15). High-resolution carbon dioxide concentration record 650,000-800,000 years before present. Nature, 453, 379-382.
• McKinley, G.A. (2010). Carbon and Climate. University of Wisconsin-Madison. Accessed May 4, 2011.
• Oren, R., Ellsworth, D.S., Johnsen, K.H., Phillips, N., Ewers, B.E., Maier, C., Schäfer, K.V.R., McCarthy, H., Hendrey, G., McNulty, S.G., and Katul, G.G. (2001, May 24). Soil fertility limits carbon sequestration by forest ecosystems in a CO2-enriched atmosphere. Nature, 411, 469-472.
• Orr, J.C. et al. (2005, September 29). Anthropogenic ocean acidification over the twenty-first century and its impact on calcifying organisms. Nature, 437, 681-686.
• Rothman, L.S., Gordon, I.E., Barbe, A., Benner, D.C., et al. (2009, June-July). The HITRAN 2008 molecular spectroscopic database. Journal of Quantitative Spectroscopy and Radiative Transfer, 110 (9-10), 533-572.
• Sabine, C.L. and Feely, R.A. (2007). The oceanic sink for carbon dioxide. In Greenhouse Gas Sinks, eds D.S. Reay, C.N. Hewitt, K.A. Smith, and J. Grace. CAB International.
• Sabine, C.L., et al. (2004, July 16). The oceanic sink for anthropogenic CO2. Science, 305 (5682), 367-371.
• Schlesinger, W.H. (1991). Biogeochemistry, An Analysis of Global Change. San Diego: Academic Press.
• Schmidt, G.A., Ruedy, R.A., Miller, R.L., and Lacis, A.A. (2010, October 16). Attribution of the present-day total greenhouse effect. Journal of Geophysical Research, 115, D20106.
• Schmidt, G. (2010, October). Taking the measure of the greenhouse effect. NASA Goddard Institute for Space Studies. Accessed December 17, 2010.
• Schuur, E.A.G., Bockheim, J., Canadell, J.G., Euskirchen. E, Field, C.B., Goryachkin, S.V., Hagemann, S., Kuhry, P., Lafleur, P.M., Lee, H., Mazhitova, G., nelson, F.E., Rinke, A., Romanovsky, V.E., Shiklomanov, N., Tarnocai, C., Venevsky, S., Vogel, J.G., and Zimov, S.A. (2008, September). Vulnerability of permafrost carbon to climate change: Implications for the global carbon cycle. BioScience, 58 (8), 701-714.
• Scientific Committee of Problems of the Environment 13. (1979). Carbon in the rock cycle. In The Global Carbon Cycle, B. Bolin, E.T. Degens, S. Kempe, and P. Ketner, eds. Accessed May 4, 2011.
• Sellers, P. J., Hall, F. G., Asrar, G., Strebel, D. E., and Murphy, R. E. (1992, November 30). An Overview of the First International Satellite Land Surface Climatology Project (ISLSCP) Field Experiment (FIFE), Journal of Geophysical Research, 97 (D17), 18,345–18,371.
• Tarnocai, C., Canadell, J.G., Schuur, E.A.G., Kuhry, P., Mazhitova, G., and Zimov, S. (2009, June 27). Soil organic carbon pools in the northern circumpolar permafrost region. Global Biogeochemical Cycles, 23, GB2023.
• United States Department of Energy. (2008, October 9). How fossil fuels were formed. Accessed December 17, 2010.
• United States Geological Survey. (2010, August 5). Volcanic gases and climate change overview. Accessed May 4, 2011.
• van der Werf, G.R., Morton, D.C., DeFries, R.S., Olivier, J.G.J., Kasibhatla, P.S., Jackson, R.B., Collatz, G.J., and Randerson, J.T. (2009, November). CO2 emissions from forest loss. Nature Geoscience, 2, 737-738.
• Zachos, J., M. Pagani, L. Sloan, E. Thomas, and K. Billups. (2001, April 27). Trends, Rhythms, and Aberrations in Global Climate 65 Ma to Present. Science, 292, (5517), 686-693.
• Zeebe, R.E., and Caldeira, K. (2008, May). Close mass balance of long-term carbon fluxes from ice-core CO2 and ocean chemistry records. Nature Geoscience, 1, 312-315.

Atmosphere Land

Teacher Resource Center

Pasco partnerships.

2024 Catalogs & Brochures

Carbon cycle chemistry.

How does pH data provide evidence of the chemical reactions that cycle carbon through water, air, land, and life forms? In this investigation, students use pH sensors to indirectly track the movement of carbon through the biosphere and hydrosphere in miniature aquatic ecosystems. This investigation provides an opportunity to incorporate Earth Science, Chemistry, and Biology concepts while collecting and interpreting pH data.

Grade Level: High School • Middle School

Subject: Biology • Chemistry • Earth Science • Environmental Science

Student Files

Teacher Files

Sign In to your PASCO account to access teacher files and sample data.

Featured Equipment

Wireless pH Sensor

Here’s the best tool for measuring pH since litmus paper. The Wireless pH Sensor connects via Bluetooth® to monitor the pH of solutions.

Many lab activities can be conducted with our Wireless , PASPORT , or even ScienceWorkshop sensors and equipment. For assistance with substituting compatible instruments, contact PASCO Technical Support . We're here to help. Copyright © 2021 PASCO

More Experiments

Advanced Placement

• Plasmolysis

High School

• Digital Microscopy Journal
• Energy Content of Food
• Plant Pigments and Photosynthesis
• Buffers in Biological Systems

Middle School

• How a Greenhouse Works: Light

• Sign in / Register
• Administration
• Edit profile

The PhET website does not support your browser. We recommend using the latest version of Chrome, Firefox, Safari, or Edge.

Was ist Feuer?

• First Online: 28 November 2017

Cite this chapter

• Ralf Geiß 3  

Part of the book series: Chemie – Entdecken und verstehen ((CHEENVER))

5706 Accesses

Zusammenfassung

Als Einstieg in Chemie wird, nur mit Experimenten, eine Antwort auf die Frage: „Was ist Feuer?“ gesucht. Da man in Innenräumen kein Lagerfeuer entzünden kann, werden Flammen von Kerzen und Gasbrennern untersucht.Dabei stehen die folgenden Fragen im Mittelpunkt:

Wie sieht eine Kerzenflamme aus?

Was brennt in der Kerzenflamme?

Woraus bestehen die Flammenzonen?

Was passiert bei der Verbrennung von Kerzenwachs?

Durch zahlreiche chemische Experimente gelingt es, diese Fragen zu beantworten. Die Versuche machen zugleich deutlich, dass chemische Reaktionen magische Vorgänge sind, die alle eine Gemeinsamkeit aufweisen. Es geht in diesem Kapitel jedoch nicht nur darum, chemisches Fachwissen zugänglich zu machen. Der Forschungsprozess offenbart zugleich, dass man die grundlegenden Fragen nicht mit Experimenten lösen kann - man muss sich zu deren Beantwortung etwas ausdenken. Auf andere Weise kommt man bei der Erforschung der Natur nicht voran.

This is a preview of subscription content, log in via an institution to check access.

Access this chapter

• Available as PDF
• Read on any device
• Instant download
• Own it forever
• Available as EPUB and PDF
• Compact, lightweight edition
• Dispatched in 3 to 5 business days
• Free shipping worldwide - see info

Tax calculation will be finalised at checkout

Purchases are for personal use only

Institutional subscriptions

Annaud J-J (1981) Am Anfang war das Feuer (Originaltitel: La Guerre du feu). Film, Kanada, Frankreich, USA

Google Scholar  

Beretta M (1999) Lavoisier: Die Revolution in der Chemie. Spektrum der Wissenschaft: (Biographie Nr. 3), Heidelberg

Zeitzuleben.de (2016) Die Angst der Kerze. http://www.zeitzuleben.de/die-angst-der-kerze/ . Zugegriffen: 8. Febr 2016 (Der Text der Website wurde leicht abgeändert)

Internet-Märchen.de (2010) Die Aufgabe des Königs. http://www.internet-maerchen.de/maerchen/aufgabe_koenig.htm . Zugegriffen: 17. April 2010

Evolution-Mensch.de (2009) Die Bedeutung von Feuer in der Evolution des Menschen. http://www.evolution-mensch.de/thema/feuer/bedeutung-feuer.php . Zugegriffen: 14. Nov 2009

Merck Millipore (2013) Stoffdaten von Chemikalien. http://www.merckmillipore.com/germany/chemicals . Zugegriffen: 16. Febr 2013

Download references

Author information

Authors and affiliations.

Halle, Deutschland

You can also search for this author in PubMed   Google Scholar

Corresponding author

Correspondence to Ralf Geiß .

Rights and permissions

Reprints and permissions

Copyright information

© 2017 Springer-Verlag GmbH Deutschland

About this chapter

Geiß, R. (2017). Was ist Feuer?. In: Die Verwandlung der Stoffe. Chemie – Entdecken und verstehen. Springer Spektrum, Berlin, Heidelberg. https://doi.org/10.1007/978-3-662-54708-3_2

Download citation

DOI : https://doi.org/10.1007/978-3-662-54708-3_2

Published : 28 November 2017

Publisher Name : Springer Spektrum, Berlin, Heidelberg

Print ISBN : 978-3-662-54707-6

Online ISBN : 978-3-662-54708-3

eBook Packages : Life Science and Basic Disciplines (German Language)

Share this chapter

Anyone you share the following link with will be able to read this content:

Sorry, a shareable link is not currently available for this article.

Provided by the Springer Nature SharedIt content-sharing initiative

• Publish with us

Policies and ethics

• Find a journal
• Track your research

Ähnliche Themen

Hol dir alle Funktionen.

Mit unserer App hast du immer und überall Zugriff auf alle Funktionen.

Get the best learning hacks!

Lorem ipsum dolor sit amet, consetetur sadipscing elitr, sed diam nonumy eirmod tempor invidunt ut labore et dolore magna aliquyam erat, sed diam voluptua.

Kohlenwasserstoffe im Abi

Kohlenwasserstoffe sind Verbindungen nur aus Kohlenstoff und Wasserstoff . Zu den Kohlenwasserstoffen zählen Alkane, Alkene, Alkine und Aromaten .

Eigenschaften

Kohlenwasserstoffe sind unpolar . Zwischen den Molekülen entstehen Van-der-Waals-Wechselwirkungen .

Je länger die Kohlenstoffkette ist, desto größer sind die Van-der-Waals-Kräfte und daher steigen die Schmelz- und Siedetemperaturen .

Für die Alkane gilt bei 20 °C:

Verzweigte Kohlenwasserstoffe haben tiefere Schmelz- und Siedetemperaturen , da die Van-der-Waals-Kräfte hier nicht mehr so stark sind.

Beim Verbrennen von flüssigen Kohlenwasserstoffen entsteht viel Energie . Das wird z.B. bei Heizöl genutzt.

Aromaten sind wegen der delokalisierten Elektronen sehr stabil .

Hier siehst du die verschiedenen Kohlenwasserstoffe mit ihren Merkmalen und typischen Reaktionen.

Bei der Benennung der Kohlenwasserstoffe kannst du so vorgehen:

• Hauptkette suchen
• Hauptkette benennen
• Seitenketten benennen
• Reste alphabetisch vor die Hauptkette schreiben
• Zahlen herausfinden

simpleclub ist am besten in der App.

Mit unserer App hast du immer und überall Zugriff auf: Lernvideos, Erklärungen mit interaktiven Animationen, Übungsaufgaben, Karteikarten, individuelle Lernpläne uvm.

Related topics

Jetzt simpleclub azubi holen.

Mit simpleclub Azubi bekommst du Vollzugang zur App: Wir bereiten dich in deiner Ausbildung optimal auf deine Prüfungen in der Berufsschule vor. Von Ausbilder*innen empfohlen.