temperature affecting the rate of reaction experiment

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As you increase the temperature the rate of reaction increases. As a rough approximation, for many reactions happening at around room temperature, the rate of reaction doubles for every 10°C rise in temperature.

You have to be careful not to take this too literally. It doesn't apply to all reactions. Even where it is approximately true, it may be that the rate doubles every 9°C or 11°C or whatever. The number of degrees needed to double the rate will also change gradually as the temperature increases.

Some reactions are virtually instantaneous - for example, a precipitation reaction involving the coming together of ions in solution to make an insoluble solid, or the reaction between hydrogen ions from an acid and hydroxide ions from an alkali in solution. So heating one of these won't make any noticeable difference to the rate of the reaction.

Almost any other reaction you care to name will happen faster if you heat it - either in the lab, or in industry.

Particles can only react when they collide. If you heat a substance, the particles move faster and so collide more frequently. That will speed up the rate of reaction.

That seems a fairly straightforward explanation until you look at the numbers!

It turns out that the frequency of two-particle collisions in gases is proportional to the square root of the kelvin temperature. If you increase the temperature from 293 K to 303 K (20°C to 30°C), you will increase the collision frequency by a factor of:

That's an increase of 1.7% for a 10° rise. The rate of reaction will probably have doubled for that increase in temperature - in other words, an increase of about 100%. The effect of increasing collision frequency on the rate of the reaction is minor. The important effect is quite different . . .

Collisions only result in a reaction if the particles collide with enough energy to get the reaction started. This minimum energy required is called the activation energy for the reaction.

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Only those particles represented by the area to the right of the activation energy will have enough energy to react when they collide. The great majority don't have enough energy, and will simply bounce apart. If there are very few particles with enough energy at any time, then the reaction will be slow.

Just by chance, every particle will at some time find itself with enough energy to react if it makes a successful collision. So although at any instant there may only be relatively few particles present with enough energy, given time all the particles will react if the reacting proportions are right.

In the next diagram, the graph labelled is at the original temperature. The graph labelled is at a higher temperature.

If you now mark the position of the activation energy, you can see that although the curve hasn't moved very much overall, there has been such a large increase in the number of the very energetic particles that many more now collide with enough energy to react.

Remember that the area under a curve gives a count of the number of particles. On the last diagram, the area under the higher temperature curve to the right of the activation energy looks to have at least doubled - therefore at least doubling the rate of the reaction.

Increasing the temperature increases reaction rates because of the disproportionately large increase in the number of high energy collisions. It is only these collisions (possessing the activation energy for the reaction) which result in a reaction.

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© Jim Clark 2002 (last modified October 2018)

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• Preparatory

Lesson Explainer: Effects of Temperature and Concentration on Rates of Reactions Science • Third Year of Preparatory School

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In this explainer, we will learn how to describe and explain the effect temperature and concentration have on the rate of chemical reactions.

The speed at which a chemical reaction takes place is known as the rate of reaction. Usually, the rate of reaction describes how some variable changes over a certain period of time. A common way to measure the rate of a chemical reaction is to measure how the concentrations of the reactants and products change over a certain period of time.

Definition: Rate of Reaction

• The rate of reaction measures how reactant or product concentrations change per unit time.

The rate of a chemical reaction can be affected by many factors. By changing some of these factors, the rate of reaction can be increased or decreased.

The factors that affect the rate of reaction include surface area, temperature, concentration, and the addition of catalysts. We will focus on temperature and concentration.

In order for two particles to react, they must first collide. In addition, the particles must have a certain amount of energy when they collide.

Any factor that can increase the frequency of collisions, or the energy of the particles, will likely increase the rate of reaction.

Example 1: Identifying in Which Box of Particles the Number of Collisions Will Be Greatest

The boxes below represent a chemical reaction between the red and the blue particles. In which box will the number of collisions be greatest?

A chemical reaction occurs when reactants collide with each other. The greater the number of collisions that occur, the more likely the reaction to happen and the faster the rate of reaction.

There are several factors that can affect the rate of reaction. However, from the question and diagram, we can see that we are given four boxes each containing different numbers of particles. The size of the box is also the same in each case.

If the particles are moving randomly, then the more particles there are, the more collisions there are likely to be.

We can see from the diagram that box A contains the greatest number of particles. Therefore, the number of collisions is likely to be greatest in box A.

The answer is box A.

One way to increase the number of collisions is by increasing the temperature. As the temperature increases, the particles gain energy and move faster. The faster the particles move, the more likely they are to collide with each other.

In the diagram below, the larger the arrow, the faster the particle is moving. At higher temperatures, the particles have more energy and so a larger arrow.

The effect of temperature on the rate of reaction can easily be demonstrated in a laboratory experiment. In this experiment, one effervescent tablet is put into a flask that contains hot water and a second tablet is put into a different flask that contains cold water.

The tablet reacts with the water to produce carbon dioxide gas. The experimental setup is shown below.

By measuring the volume of gas produced in each experiment, the rates of reaction can be determined and compared.

The results of this experiment are shown in the graph below:

At the higher temperature, the particles have more energy and move around faster. This increases the number of collisions between particles and increases the rate of reaction.

A faster rate of reaction increases the volume of gas produced at the start of the reaction, resulting in a steeper line on the graph. However, as the mass of the tablet and volume of water remain constant, the final amount of gas produced is the same.

Example 2: Relating Temperature to the Frequency of Collisions between Molecules

The boxes below each contain an equal number of reactant molecules. The boxes are heated to different temperatures. Which box will have the greatest frequency of collisions between molecules?

In order for two reactant molecules to react, they have to collide. There are several factors that can increase the number of collisions between reactant molecules. One of these is temperature.

We are told that each box contains the same number of reactant molecules, so the frequency of collisions is not going to be affected by a different number of molecules. However, the temperature of each box is different, and so, the main effect on the frequency of collisions will be the change in temperature.

As the temperature increases, the reactant molecules gain energy and move faster. The faster the molecules are moving, the more likely they are to collide and the greater the frequency of collisions will be.

The higher the temperature, the greater the frequency of collisions between molecules. Looking at the diagram, we can see that the box with the highest temperature is box D. Therefore, the answer is box D.

Temperature is a very important factor for controlling the rate of reactions in food. Placing food in a cool place, such as a refrigerator or freezer, slows down the chemical reactions that spoil food. As a result, food can be preserved and last longer.

High temperatures are often used when cooking food. The higher temperature increases the rate of reaction and helps cook food quicker and more thoroughly.

The effect of concentration on the rate of reaction can be explained by looking at the frequency of collisions.

Consider the reaction between the purple particles A and the green particles B shown in the diagram below.

If the concentration of B is increased, then the number of particles of B present increases. This is shown in the diagram below.

An increase in the number of particles will result in an increase in the number of collisions. A greater number of collisions causes an increase in the rate of reaction.

The effect of concentration on the rate of reaction can be demonstrated using the reaction of iron wool and oxygen.

Iron wool, also known as steel wool, can be burned in the presence of oxygen. However, the speed and intensity of this reaction changes when the concentration of oxygen changes.

When burned over a Bunsen burner, the iron wool is being burned in air. Air contains 2 1 % of oxygen, a medium to low concentration. The rate of reaction is quite low, and the iron wool burns relatively slowly.

However, when burned in pure oxygen the reaction is much more rapid and intense. The concentration of pure oxygen is ∼ 1 0 0 % , much greater than air. The increase in oxygen concentration increases the rate of reaction and results in a more vigorous and fast reaction.

These two experiments are shown in the image below.

Example 3: Explaining the Different Rates of Combustion in Air Compared with Pure Oxygen

Why is the combustion of aluminum in air slower than in pure oxygen?

• The temperature of oxygen in air is greater than in pure oxygen.
• The temperature of pure oxygen is greater than air.
• The concentration of oxygen in air is less than in pure oxygen.
• The concentration of oxygen in air is greater than in pure oxygen.

The process of combustion usually refers to the reaction of a substance with oxygen. Here, aluminum is reacted with oxygen under two different conditions.

The combustion of aluminum in air is most likely performed using a Bunsen burner. Air usually contains around 2 1 % oxygen, a relatively low amount of oxygen.

The combustion of aluminum with pure oxygen most likely involves conditions where there is ∼ 1 0 0 % oxygen. We can see that the difference between burning in air and in pure oxygen is the amount, or concentration, of oxygen present.

From this, we can conclude that the difference in the rate of combustion is because of the different concentrations of oxygen. Our answer is therefore likely to be either C or D.

Concentration can affect the rate of reaction by changing the number of reactant molecules present. The more reactant molecules there are, the greater the number of collisions that will occur between them and the faster the rate of reaction is.

As concentration increases, the rate of reaction increases.

The combustion of aluminum in air is slower because the concentration of oxygen is lower than in pure oxygen. This statement matches with choice C, and so our answer is C.

Another experiment that shows the effect of concentration on the rate of reaction is the reaction of magnesium with hydrochloric acid.

In this experiment, one conical flask contains dilute hydrochloric acid and a different flask contains concentrated hydrochloric acid. Into each conical flask is placed an identical piece of magnesium of the same size and mass.

The chemical equation for the reaction between magnesium and hydrochloric acid is M g ( ) + 2 H C l ( ) M g C l ( ) + H ( ) s a q a q g 2 2

Therefore, by measuring the volume of hydrogen gas produced over time, any change in the rate of reaction can be determined.

The setup of this experiment is shown in the image below:

By plotting a graph of the volume of hydrogen gas produced against time, the rates of reaction for each experiment can be determined. A graph showing the rate of reaction for dilute and concentrated hydrochloric acid is shown below:

The graph shows that a greater volume of hydrogen gas is produced over a short period of time when concentrated hydrochloric acid is used. This shows that the rate of reaction increases as the concentration increases.

As the concentration of hydrochloric acid increases, the number of acid particles present increases. As a result, there is a greater number of collisions between the acid and the magnesium particles, and so, there is an increase in the rate of reaction.

Example 4: Ordering Experiments with Differing Concentration by Their Rate of Reaction

A chemist performs a series of experiments to determine the effect of concentration on the rate of a reaction. They pour an equal amount of hydrochloric acid of different concentrations into four test tubes, then they place an identical piece of magnesium ribbon into each of the test tubes. The experiment setup is shown below.

From slowest to quickest, what is the likely ordering of the rate of reaction for the four experiments?

There are several factors that can affect the rate of reaction. These include concentration and surface area. In the experiment, the volume of hydrochloric acid used is kept the same. An identical piece of magnesium is also used, and so, the surface area and mass are kept the same.

The only factor that is changing is the concentration of hydrochloric acid. The concentration is greatest for experiment D and lowest in experiment B.

For a reaction to occur, the reactant molecules must collide with each other. Increasing the number of collisions increases the rate of reaction.

When the concentration is increased, the number of acid particles present in the solution increases. The increased number of acid particles will result in a greater number of collisions and therefore a faster rate of reaction.

If the rate of reaction increases as the concentration increases, then the order of the rate reaction from slowest to quickest will correspond to the order from the lowest to the greatest concentration.

From slowest to quickest, the likely ordering is B, C, A, D, which corresponds to answer choice D. The correct answer is therefore D.

Example 5: Identifying Which Set of Conditions Gives the Greatest Rate of Reaction

In a series of experiments, a student changes both the concentration and the temperature. The conditions for each experiment are shown below. In which conical flask is the rate of reaction likely to be highest?

The rate of a reaction is affected by both temperature and concentration. For a reaction to occur, reactant particles must collide with each other. Any factor that increases the number of collisions is likely to increase the rate of reaction.

As the temperature increases, the particles are given more energy and can move faster. As a result, there is likely to be a greater number of collisions and a faster rate of reaction. Therefore, the rate of reaction increases as the temperature increases.

As the concentration increases, the number of reactant particles increases. With a greater number of particles present, there is likely to be a greater number of collisions and a faster rate of reaction. Therefore, the rate of reaction increases as the concentration increases.

From the two statements above, we can conclude that the rate of reaction is likely to be highest when both the temperature and the concentration are greatest.

In the diagram above, we can see that the highest temperature is 5 0 ∘ C and the highest concentration is 2 mol/L , which occurs in experiment C.

The rate of reaction is therefore likely to be highest for experiment C.

• For a chemical reaction to occur, reactant particles must collide with each other.
• Generally, as the number of collisions between reactant particles increases, the rate of reaction increases.
• When the temperature increases, the particles gain more energy and the number of collisions increases, causing the rate of reaction to increase.
• The effect of temperature on the rate of reaction can be seen experimentally by reacting effervescent tablets with water and measuring the volume of gas produced.
• Increasing the concentration increases the number of particles present. There is a greater number of collisions, and so, the rate of reaction increases.
• The combustion of substances such as iron wool in pure oxygen is faster than in air because the concentration of oxygen is lower in air.
• The effect of concentration on the rate of reaction can be seen experimentally by reacting magnesium with different concentrations of hydrochloric acid and measuring the volume of gas produced.

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The effect of concentration and temperature on reaction rate

Explore the effect that concentration and temperature have on the reaction time of chemicals with this experiment in kinetics

In this experiment, two colourless solutions are mixed to make a solution which becomes dark blue. Changing the concentration or temperature of the solutions changes the time required for the blue colour to develop.

This experiment should take 30 minutes.

• Eye protection
• Beakers, 250 cm3, x2
• Water bath (or some means of warming solution A)
• Solution A – 4.3 g of KIO 3 per dm 3
• Solution B – starch solution 

Health, safety and technical notes

• Read our standard health and safety guidance.
• Always wear eye protection.
• Both solutions are of low hazard.
• Place 50 cm 3 of solution A in a 250 cm 3 beaker.
• Place the same volume of solution B in a second beaker.
• Mix the two solutions by pouring from one beaker into the other several times.
• Note the time required for a reaction to occur (formation of blue colour).
• Repeat, but use solution A that has been diluted to one half the concentration. Note the time for the reaction to occur.
• Repeat using solution A warmed to 35 °C. Note the time for a reaction to occur. 

The colour change takes about 5–6 minutes.

A colorimeter sensor or a light sensor set up as a colorimeter can be used to monitor colour change on the computer.

The result, in the form of graphs on the computer, provides very useful material for analysis using data logging software.

While a colorimeter sensor is ideal, it is easy to substitute a light sensor clamped against a plastic cuvette filled with the reactants.

The data logging software should clearly show the change occurring on a graph.

Measure the rate of change by using its slope or the time taken for a change to occur. 

Background theory

The mechanism is not clearly understood, but the following simplified sequence has been proposed.

IO 3 − reacts with HSO 3 − to form I − :

IO 3 − + 3HSO 3 − → I − + 3H + + 3SO 4 2− 

I − reacts with IO 3 − to form I 2 . 

I 2 is immediately consumed by reacting with HSO 3 −:

I 2 + HSO 3− + H 2 O → 2 I − + SO 4 2− + 3H +

When all of the HSO 3− has been used up, I 2 accumulates.

Iodine reacts with starch to form a coloured complex.

• Why does increasing the concentration usually result in an increased rate of reaction?
• Why does increasing the temperature usually result in an increased rate of reaction? 
• How could this experiment be set up, so it took exactly 10 min to turn blue?
• There are more molecules of reactant in the solution, therefore more chance of reacting.
• Increasing the temperature has two effects. Since the particles are moving faster, they will travel a greater distance in a given time and so will be involved in more collisions. In addition, because the particles are moving faster, a larger proportion of the collisions will exceed the activation energy, the energy needed to react. The rate of the reaction therefore increases.
• Depending on the results of the experiment, increase/decrease concentration to a specific amount AND/OR increase/decrease the temperature by a specific amount. 

The effect of concentration and temperature on reaction rate – teacher notes

The effect of concentration and temperature on reaction rate – student sheet, additional information.

This practical is part of our  Classic chemistry experiments  collection.

• 11-14 years
• 14-16 years
• Practical experiments
• Physical chemistry
• Rates of reaction

Specification

• Use initial concentration–time data to deduce the initial rate of a reaction.
• 4 i. understand experiments that can be used to investigate reaction rates by: an initial-rate method, carrying out separate experiments where different initial concentrations of one reagent are used
• an initial rate method such as a clock reaction
• PAG.10 Rates of reaction – initial rates method
• l) measurement of rates of reaction by at least two different methods, for example: an initial rate method such as a clock reaction; a continuous monitoring method.
• h) the techniques and procedures used to investigate reaction rates by the initial rates method and by continuous monitoring, including use of colorimetry
• AT.5 Making and recording of appropriate observations during chemical reactions including changes in temperature and the measurement of rates of reaction by a variety of methods such as production of gas and colour change.
• 5 Investigate how changes in concentration affect the rates of reactions by a method involving measuring the volume of a gas produced and a method involving a change in colour or turbidity. This should be an investigation involving developing a hypothesi…
• Factors which affect the rates of chemical reactions include: the concentrations of reactants in solution, the pressure of reacting gases, the surface area of solid reactants, the temperature and the presence of catalysts.
• Students should be able to recall how changing these factors affects the rate of chemical reactions.
• RP19 Investigation of how changes in concentration affect the rates of reactions by a method involving measuring the volume of a gas produced and a method involving a change in colour or turbidity. This should be an investigation involving developing…
• Explain the effects on rates of reaction of changes in temperature, concentration and pressure in terms of the frequency and energy of collision between particles.
• Describe the effect of changes in temperature, concentration, pressure, and surface area on rate of reaction.
• 11 Investigate how changes in concentration affect the rates of reactions by a method involving measuring the volume of a gas produced and a method involving a change in colour or turbidity. This should be an investigation involving developing…
• 5 Making and recording of appropriate observations during chemical reactions including changes in temperature and the measurement of rates of reaction by a variety of methods such as production of gas and colour change
• 7.1b observing a colour change (in the reaction between sodium thiosulfate and hydrochloric acid)
• 7.4 Explain the effects on rates of reaction of changes in temperature, concentration, surface area to volume ratio of a solid and pressure (on reactions involving gases) in terms of frequency and/or energy of collisions between particles
• 8 Investigation the effect of surface area, concentration and temperature on the rate of a chemical reaction
• Making and recording of appropriate observations during chemical reactions including changes in temperature and the measurement of rates of reaction by a variety of methods such as production of gas and colour change
• C6.2.1 describe the effect on rate of reaction of changes in temperature, concentration, pressure, and surface area
• C6.2.2 explain the effects on rates of reaction of changes in temperature, concentration and pressure in terms of frequency and energy of collision between particles
• C5 Investigation the effect of surface area, concentration and temperature on the rate of a chemical reaction
• C5.1c describe the effect of changes in temperature, concentration, pressure, and surface area on rate of reaction
• C5.1d explain the effects on rates of reaction of changes in temperature, concentration and pressure in terms of frequency and energy of collision between particles
• C5.2c describe the effect of changes in temperature, concentration, pressure, and surface area on rate of reaction
• C5.2d explain the effects on rates of reaction of changes in temperature, concentration and pressure in terms of frequency and energy of collision between particles
• Rates of reaction can be increased: by increasing the temperature
• by increasing the concentration of a reactant
• (b) how to calculate rates from experimental data and how to establish the relationship between reactant concentrations and rate
• (a) practical methods used to determine the rate of reaction – gas collection, loss of mass and precipitation (including using data-logging apparatus)
• (b) the effect of changes in temperature, concentration (pressure) and surface area on rate of reaction
• 2.9.1 recall how factors, including concentration, pressure, temperature and catalyst, affect the rate of a chemical reaction;
• 7. Investigate the effect of a number of variables on the rate of chemical reactions including the production of common gases and biochemical reactions.
• 2. Develop and use models to describe the nature of matter; demonstrate how they provide a simple way to to account for the conservation of mass, changes of state, physical change, chemical change, mixtures, and their separation.
• 4. Classify substances as elements, compounds, mixtures, metals, non-metals, solids, liquids, gases and solutions.
• 9. Consider chemical reactions in terms of energy, using the terms exothermic, endothermic and activation energy, and use simple energy profile diagrams to illustrate energy changes.

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Chapter 17. Kinetics

Factors that Affect the Rate of Reactions

Jessie A. Key

Learning Objectives

• To gain an understanding of collision theory.
• To gain an understanding of the four main factors that affect reaction rate.

Reaction kinetics is the study of the rate of chemical reactions, and reaction rates can vary greatly over a large range of time scales. Some reactions can proceed at explosively fast rates like the detonation of fireworks (Figure 17.1 “Fireworks at Night Over River”), while others can occur at a sluggish rate over many years like the rusting of barbed wire exposed to the elements (Figure 17.2 “Rusted Barbed Wire”).

Collision Theory

To understand the kinetics of chemical reactions, and the factors that affect kinetics, we should first examine what happens during a reaction on the molecular level. According to the collision theory of reactivity, reactions occur when reactant molecules “effectively collide.” For an “effective collision” to occur, the reactant molecules must be oriented in space correctly to facilitate the breaking and forming of bonds and the rearrangement of atoms that result in the formation of product molecules (see Figure 17.3 “Collision Visualizations”).

During a molecular collision, molecules must also possess a minimum amount of kinetic energy for an effective collision to occur. This energy varies for each reaction, and is known as the activation energy ( E a ) (Figure 17.4 “Potential Energy and Activation Energy”). The rate of reaction therefore depends on the activation energy; a higher activation energy means that fewer molecules will have sufficient energy to undergo an effective collision.

Factors That Affect Rate

There are four main factors that can affect the reaction rate of a chemical reaction:

• Reactant concentration. Increasing the concentration of one or more reactants will often increase the rate of reaction. This occurs because a higher concentration of a reactant will lead to more collisions of that reactant in a specific time period.
• Physical state of the reactants and surface area. If reactant molecules exist in different phases, as in a heterogeneous mixture, the rate of reaction will be limited by the surface area of the phases that are in contact. For example, if a solid metal reactant and gas reactant are mixed, only the molecules present on the surface of the metal are able to collide with the gas molecules. Therefore, increasing the surface area of the metal by pounding it flat or cutting it into many pieces will increase its reaction rate.

• Presence of a catalyst . A catalyst is a substance that accelerates a reaction by participating in it without being consumed. Catalysts provide an alternate reaction pathway to obtain products. They are critical to many biochemical reactions. They will be examined further in the section “Catalysis.”

Key Takeaways

• Reactions occur when two reactant molecules effectively collide, each having minimum energy and correct orientation.
• Reactant concentration, the physical state of the reactants, and surface area, temperature, and the presence of a catalyst are the four main factors that affect reaction rate.

Media Attributions

• “Fireworks at night over river” © Jon Sullivan is licensed under a Public Domain license
• “Barbed wire (rusting after years of hard work)” © 2007 by Waugsberg is licensed under a CC BY-SA (Attribution-ShareAlike) license

Factors that Affect the Rate of Reactions Copyright © 2014 by Jessie A. Key is licensed under a Creative Commons Attribution 4.0 International License , except where otherwise noted.

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Science News Explores

Experiment: test the effect of temperature on reaction time.

Can you make an Alka-Seltzer tablet dropped in water fizzle faster or more loudly by changing the water’s temperature?

Figure 1. In this experiment, we investigate how to make Alka-Seltzer tablets plunked in water fizzle faster and more furiously.

asadykov/iStock/Getty Images Plus

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• Google Classroom

By Science Buddies

July 12, 2023 at 6:30 am

Objective : To measure the effect of temperature on the rate of a chemical reaction

Areas of science : Chemistry, science with your smartphone

Difficulty : Easy intermediate

Time required : 2–5 days

Prerequisites : None

Material availability : Readily available

Cost : Very low (under $20)

Safety : Adult supervision may be needed when working with hot water solutions

Credits : Andrew Olson, PhD, Science Buddies; edited by Svenja Lohner, PhD, Science Buddies

You may have seen a television commercial for Alka-Seltzer tablets or heard one of their advertising slogans: “Plop, plop, fizz, fizz, oh what a relief it is!” When you drop the tablets in water, they make a lot of bubbles, like an extra-fizzy soda, as shown in the main image up top (Figure 1). And like a soda, the bubbles are carbon dioxide gas (CO 2 ). However, with Alka-Seltzer, the CO 2  is produced by a  chemical reaction  that occurs when the tablets dissolve in water.

Alka-Seltzer  is a medical drug that works as a pain reliever and an  antacid  (antacids help neutralize stomach acidity, such as heartburn). The pain reliever used is aspirin and the antacid used is  baking soda (sodium bicarbonate, NaHCO 3 ). To take the tablets, they should be fully dissolved in a glass of water. When sodium bicarbonate dissolves in water, it dissociates (splits apart) into sodium (Na + ) and bicarbonate (HCO 3 ) ions. (An  ion  is a  molecule  that has a charge, either positive or negative.) The bicarbonate reacts with hydrogen ions (H + ) from citric acid (another ingredient in the tablets) to form carbon dioxide gas and water. In other words, carbon dioxide gas is a  product  of this reaction. The reaction is described by Equation 1 below:

Equation 1. 3HCO 3 − + 3H + → 3H 2 O + 3CO 2

So how is  temperature  related to this  bicarbonate reaction ? In order for the reaction shown above to occur, the bicarbonate ions have to come into contact with the hydrogen ions. Molecules in a solution are in constant motion and are constantly colliding with one another. The hydrogen and bicarbonate ions must collide at the right angle and with enough energy for the reaction to occur. The temperature of a solution is a measure of the average motion ( kinetic energy ) of the molecules in the solution. The higher the temperature, the faster the molecules are moving. What effect do you think temperature will have on the speed, or  rate , of the bicarbonate reaction?

In this chemistry science project, you will find out for yourself by plopping Alka-Seltzer tablets into water at different temperatures and measuring how long it takes for the chemical reaction to go to completion. In addition, you can record the sound of the Alka-Seltzer fizzle using a smartphone equipped with a sensor app. Do you think it will fizz more loudly in hot or cold water?

Terms and Concepts

• Chemical reaction
• Alka-Seltzer
• Baking soda, or sodium bicarbonate
• Temperature
• Bicarbonate reaction
• Reaction rate
• What is the bicarbonate reaction? What are its products?
• Keeping in mind that an increase in temperature reflects an increase in the average molecular motion, how do you think increasing temperature will affect the reaction rate?
• What temperature change do you think would be required to increase, or decrease, the reaction time by a factor of two?
• What other factors besides temperature can affect how well a chemical reaction takes place?

Materials and Equipment

• Alka-Seltzer tablets (at least 12; if you plan to do additional variations to the project, you will want to get a larger box)
• A suitable thermometer is available from  Amazon.com
• A standard kitchen candy thermometer will also work fine
• Clear drinking glasses or jars; about 8 ounces, or 240 milliliters (two of the same size)
• Graduated cylinder, 100 mL. A 100 mL graduated cylinder is available from Amazon.com . Alternatively, measuring cups may be used.
• Masking tape
• Hot and cold tap water
• With option 2 in procedure: Stopwatch or a clock or watch with a second hand
• Optional: A helper
• Lab notebook
• With option 1 in procedure: Smartphone with a sensor app such as phyphox, available for free on  Google Play  for Android devices (version 4.0 or newer) or from the  App Store  for iOS devices (iOS 9.0 or newer).
• With option 1 in procedure: Small sealable (waterproof) plastic bag that fits your phone inside of it

Experimental Procedure

Note : In this science project, you will investigate how water temperature affects the dissolving time of an Alka-Seltzer tablet. You will use a smartphone equipped with a sensor app to record the fizzing sound of the Alka-Seltzer reaction in water and measure the time it takes for one Alka-Seltzer tablet to react completely in water. The app creates a graph that will not only give you information about the reaction time but will also allow you to assess how loud each reaction was based on the measured sound intensities. If you do not have a phone, you can observe the reaction and use a stopwatch to time how long it takes for each tablet to dissolve.

• Do your background research and make sure that you are familiar with the terms and concepts in the Background.
• In your lab notebook, make a data table like Table 1. You will record your results in this data table.
• Add 200 mL (a little less than 1 cup) of water to the drinking glass, or fill it up to about 1 inch below the rim.
• Use a piece of masking tape on the outside of the glass to mark the water level, placing the tape with its top edge even with the water level in the glass, as shown in Figure 2.
• Note:  You do not want to fill the glass completely full because the bicarbonate reaction produces bubbles that could splash out.
• For the hot and cold tap water, run the water until the temperature stabilizes. Fill the glass with water to the level of the masking tape. Be careful when handling the hot water.
• For ice water, fill the glass about half full with ice cubes, then add cold tap water to a bit above the level of the masking tape. Stir for a minute or two so that the temperature equilibrates. Once temperature has equilibrated, remove the ice cubes from the water’s surface using a spoon or other utensil immediately before adding the Alka-Seltzer tablet. (Pour out any extra water so that the water is up to the level of the masking tape.)

• Open the sensor app on your phone and select the sound sensor (audio amplitude in phyphox). Remember, that when you are using the phyphox app you will have to calibrate the audio amplitude sensor (sound sensor) before you do any measurements. Do this calibration before you start your investigation, so you get correct sound intensity readings. To calibrate your sound sensor in phyphox, follow the instructions in the sound sensor calibration video . You will have to re-calibrate the audio amplitude sensor (re-set the decibel offset) every time you start a new recording! Once you have calibrated the sensor, make sure you know where the microphone is located on your phone and do a quick test to see if your sound measurement is working. For example, you could record yourself clapping or singing to check if the sensor behaves as expected.
• Once you have confirmed that the sensor works and you are familiar with the app, you can start with the experiment. You should do this experiment in a quiet environment. The background reading of your sound meter when there is no noise in the room should be in the range between 20–40 decibels (dB).
• Measure the temperature of the water (in Celsius [C]) in the first glass that you prepared, and record it in the data table in your lab notebook. Remove the thermometer from the glass before continuing with the next step.
• Put your phone in the waterproof plastic bag and make sure it is sealed well. You don’t want it to get wet!

• Take one whole Alka-Seltzer tablet out of its package and hold it above the glass filled with water. In the phyphox app, start a new recording for your first experiment by pressing the play button.
• Once the recording starts, drop the tablet into the water.  Note : You have to be very quiet during the experiment. Any sound that you make will be recorded and could affect your data. Try to be as quiet as possible while you are recording your data!
• You will immediately see and hear bubbles of CO 2  streaming out from the tablet.
• The tablet will gradually disintegrate. Observe the graph recorded by the app, and how the sound sensor is responding to the fizzling while all of the solid white material from the tablet disappears.

• Your data should look something like the graph in Figure 4. Your graph should show an increased sound intensity for as long as the Alka-Seltzer reaction took place. The sound level of the reaction might be louder in the beginning and decrease as the tablet gets smaller. In the graph, every bubble that pops in the solution is represented by a spike.
• Measure the time between the beginning of your reaction (when you dropped the tablet and the sound intensity started to increase) and the end of the reaction (when the sound intensity reached background levels again or does not change significantly anymore). In phyphox, you can use the “pick data” function to select the respective data points and view their time and decibel values. For example, the reaction in Figure 4 started a little after 3 seconds and ended at about 66 seconds.
• Calculate the time difference between these two points. The result is the reaction time for your first trial. Record the reaction time (in seconds [s]) in the data table in your lab notebook.
• Tip:  Be careful when opening the packets and handling the Alka-Seltzer tablets. The tablets are thin and brittle, so they break easily. If some of the tablets are whole, and some are broken into many pieces, the separate trials will not be a fair test. You should only use whole tablets.
• After filling the glass to the level of the masking tape, measure the temperature of the water (in Celsius [C]), and record it in the data table in your lab notebook.
• Remove the thermometer from the glass before continuing with the next step.
• Have your helper get ready with the stop watch, while you get ready with an Alka-Seltzer tablet. Have your helper count one–two–three. On three, the helper starts the stop watch and you drop the tablet into the water.
• You will immediately see bubbles of CO 2  streaming out from the tablet.
• The tablet will gradually disintegrate. Watch for all of the solid white material from the tablet to disappear.
• When the solid material has completely disappeared, and the bubbles have stopped forming, say “Stop!” to have your helper stop the stopwatch.
• Record the reaction time (in seconds [s]) in the data table in your lab notebook.
• Repeating an experiment helps ensure that your results are accurate and reproducible.
• When you are done, you should have done a total of three trials for each of the three temperatures.
• Calculate the average reaction time for each of the three water temperatures. Record your results in the data table in your lab notebook.
• Make a graph of the average reaction time, in seconds (on the Y-axis), vs. water temperature, in degrees Celsius (on the X-axis).
• Hint:  If you are having trouble explaining your results, try re-reading the Introduction in the Background.
• If you chose to use a sensor app to record your data, look at the graphs for each water temperature again. Write down the maximum sound intensity that you observed during the Alka-Seltzer reaction (not including the initial or end peaks) for each trial. You can get the number in the phyphox app by using the “pick data” tool to select the timepoint at which the sound intensity is highest. In the example shown in Figure 4, this would be around 35 seconds with a sound intensity of about 50 decibels. Calculate the average for each of the three water temperatures and record your results in the data table in your lab notebook.
• Make a graph of the average maximum sound intensity, in decibels (on the Y-axis), vs. water temperature, in degree Celsius (on the X-axis).
• Which reaction was the loudest? Did you expect these results?

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• Use the standard deviation to add error bars to your graph.
• For example, say that the average reaction time for one temperature was 45 seconds, and the standard deviation was 5.2 seconds (these are made-up numbers). You would graph the symbol for the data point at 45 seconds, and then draw short vertical bars above and below the symbol. Each vertical bar would have a length equivalent to 5.2 seconds.
• Error bars give your audience a measure of the  variance  in your data.
• Adult supervision required . Is reaction rate predictable over a larger temperature range? Water remains liquid above 0° C and below 100° C. Repeat the experiment at one or more additional high temperatures to find out. Use Pyrex glass for containing water heated on the stove or in the microwave, and use appropriate care (e.g., wear hot mitts and safety goggles) when handling hot water. A standard candy thermometer should be able to measure the temperatures in this higher range.
• You could turn the bicarbonate reaction into a home-made lava lamp. To do this, you will want to use a tall jar or empty clear plastic 1-liter or 2-liter bottle, fill it with 2 to 5 centimeters (cm) of water, add 5 drops of food coloring, and then fill it at least three-quarters full with vegetable oil. You could repeat the science project using your homemade lava lamp at a cold and a hot temperature. To do this, you will need to figure out a way to make the prepared bottle hot or cold. (For example, to make it hot you could let it sit in a large bowl of hot water, and to make it cold you could store it in a refrigerator or freezer.) You will also want to use one-quarter of an Alka-Seltzer tablet at a time (instead of a whole tablet). How does the bicarbonate reaction look and function in the home-made lava lamp?

This activity is brought to you in partnership with  Science Buddies . Find  the original activity  on the Science Buddies website.

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Effect of Temperature on Reaction Rate ( AQA A Level Chemistry )

Revision note.

Chemistry Lead

Temperature & Rate of Reaction

• At higher temperatures, the particles are moving faster, so collide more frequently. A higher number of collisions in total mean a higher  number  of successful collisions

An increase in temperature causes an increase in the kinetic energy of the particles. The number of collisions increases and the proportion of successful collisions increases 

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• Chemistry Practicals
• CBSE Class 12 Chemistry Practical
• Effect Of Temperature On The Rate Of Reaction Between Sodium Thiosulphate And Hydrochloric Acid

Effect of temperature on the rate of reaction between sodium thiosulphate and hydrochloric acid

In this article, we have discussed the effect of temperature on the rate of reaction between hydrochloric acid and sodium thiosulphate.

The aim of this experiment – Understanding the effect of temperature variation on the rate of reaction between hydrochloric acid and sodium thiosulphate.

The rate of a chemical reaction is directly proportional to the temperature. As the temperature increases, the reaction rate also increases. With the increase in temperature the kinetic energy of the molecules also increases. Usually, it is observed that for every 10-degree increase in temperature the rate of reaction is doubled. Therefore, the rate of reaction of hydrochloric acid and sodium thiosulphate also increases with rise in temperature.

Materials required:

The apparatus and materials required for this experiment are as follows:

• Conical flask of volume 250 mL
• Tripod stand
• Measuring cylinder
• Thermometer
• 0.1M sodium thiosulphate solution
• Concentrated nitric acid
• Distilled water
• 1M hydrochloric acid

The effect of temperature on the rate of reaction:

• Take a conical flask of volume 100 mL.
• Add 50 mL of 0.1M sodium thiosulphate solution to it.
• With the help of a thermometer measure, the temperature of the solution which is added to the flask.
• Take 1M HCl of volume 10 mL with the help of a burette and add it to the conical flask containing sodium thiosulphate.
• Start the stopwatch as soon as you have poured half of the hydrochloric acid into the flask containing sodium thiosulphate solution.
• Take a white tile and draw a cross mark on it.
• Shake the conical flask and place it on the tile.
• Observe the flask and start the stop-watch as soon as the cross mark becomes invisible.
• Empty the flask and wash it with concentrated nitric acid first and later with distilled water.
• Take the washed flask add 50 mL of 0.1M sodium thiosulphate solution and heat it to (T+ 10)°.
• Continue the steps from points 4.
• Repeat the experiment for (T+ 20) °C, (T+ 30) °C, (T+ 40) °C and record the results.
• Record the time taken for the process.

Observation and result

Precautions to be taken during the experiment:

• Thoroughly wash the apparatus with concentrated nitric acid and distilled water.
• Take the exact quantity of solutions needed for this experiment.
• Complete the experiment in one go to avoid temperature variations.
• Use THE same tile for all the observations.
• Stay alert while you start and stop the stop-watch.

1. What is the concentration of sodium thiosulphate used for this experiment?

2. What is the concentration of hydrochloric acid used for this experiment?

3. When to start the stop-watch?

Ans: As soon as you pour half of HCl into the flask containing sodium thiosulphate solution.

4. Name the two solutions used in this experiment.

Ans: Hydrochloric acid and sodium thiosulphate.

5. What is the importance of concentrated nitric acid?

Ans: It is used in thorough washing of the apparatus used in the experiment. After washing the apparatus with HNO 3 rinse it with distilled water.

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SITEMAP  *  HOME PAGE * SEARCH * UK KS3 level Science Quizzes for students aged ~13-14

UK GCSE level Biology *  Chemistry *  Physics   age ~14-16 * Advanced Level Chemistry age ~16-18

• More details of laboratory investigations ('labs') involving 'rates of reaction' i.e. experimental methods for observing the speed of a reaction and including the effect of temperature are given in the INTRODUCTION

Theoretical interpretation of results of the effect of changing temperature on the rate of a chemical reaction

For each factor I've presented several particle diagrams to help you follow the text explaining how the particle collision theory accounts for your observations of reaction rate varying with the temperature of the reaction system (some 'work' better than others!)

A picture of a particles (ions or molecules) undergoing changes in a chemical reaction

• The greater the temperature of the reactants, the greater the average kinetic energy of the particles.
• Therefore, the more chance of a successful more energetic 'fruitful' collision between two particles with sufficient combined kinetic energy to overcome the activation energy barrier , break bonds and form the products.
• With increase in temperature, there is an increased frequency (or chance) of collision due to the more 'energetic' situation - but this is the minor factor when considering why rate of a reaction increases with temperature.
• However, the average increase in particle kinetic energy caused by the absorbed thermal energy means that a much greater proportion of the reactant molecules now has the minimum or activation energy to react.
• So, at a higher temperature, there are more particles with the higher kinetic energies.
• Therefore there will be more particles colliding with enough energy to overcome the threshold activation energy.
• It is this increased chance of a 'successful' or 'fruitful' higher energy collision leading to product formation, that is the major factor, and this effect increases more than the increased frequency of particle collision, for a similar rise in temperature.
• There is also the Arrhenius Equation relating rate of reaction and temperature - but this involves advanced level mathematics.

What next ? Associated Pages

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August 29, 2013

Carbonation Countdown: The Effect of Temperature of Reaction Time

Seltzer science from Science Buddies

By Science Buddies

Key concepts Chemical reactions Molecules Carbonation Temperature

Introduction Have you ever wondered why bubbles form when an Alka-Seltzer tablet is dropped into water? If you've ever tried it, you've seen that the tablet fizzes furiously. The moment the tablet starts dissolving a chemical reaction occurs that releases carbon dioxide gas. This is what comprises the bubbles. Some factors can change how quickly the carbon dioxide gas is produced, which consequently affect how furiously the tablet fizzes. In this activity you'll explore whether you can make an Alka-Seltzer tablet fizz faster or slower by changing the water’s temperature. How does this affect the reaction?

Background Alka-Seltzer is a medication that works as a pain reliever and an antacid. (Antacids help neutralize stomach acidity, which can cause heartburn.) The pain reliever used is aspirin and the antacid used is baking soda, or sodium bicarbonate. The tablets also include other ingredients, such as citric acid (a weak acid that adds flavor—as well as provides important hydrogen ions, which will come into play as you shall soon see).

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To take the tablets, they're fully dissolved in water, where they famously undergo a chemical reaction that produces lots of carbon dioxide bubbles—or fizz. Why is this? As the tablets dissolve, the sodium bicarbonate splits apart to form sodium and bicarbonate ions. The bicarbonate ions react with hydrogen ions from the citric acid to form carbon dioxide gas (and water). This is how the bubbles are made.

How is temperature related to this reaction? For the reaction to occur, the bicarbonate ions must come into contact with the hydrogen ions in just the right way. The probability of the bicarbonate and hydrogen ions doing this is affected by temperature: the higher the temperature, the faster the molecules move; the lower the temperature, the slower they move. (The temperature of a solution is a measure of its molecules’ average motion and energy.) Can you guess whether fast-moving molecules or slow-moving ones will speed the reaction time?

Materials • Two identical jars (You can also use drinking glasses, clear plastic cups, bottles or vases.) • Spoon • Enough ice cubes to fill one of the jars halfway • Cold tap water • Hot tap water • Two Alka-Seltzer tablets • Timer or clock that shows seconds • Optional: helper

Preparation • Fill one of the jars halfway with ice cubes. Add cold tap water to about an inch from the rim. Stir the ice cubes in the jar for about a minute so that the temperature evens out. Right before you start the activity use a spoon to remove the cubes. • Add hot tap water to the second, empty jar until it is about an inch from the rim. Be careful when handling the hot water. • Continue with the procedure immediately after preparing the jars (so that the water in the jars is still very cold or very hot).

Procedure • Drop an Alka-Seltzer tablet into the jar with hot water. Time how long it takes for the tablet to disappear. You may want to have a helper time the reaction. How long does it take the tablet to disappear? How vigorous are the bubbles? • Drop an Alka-Seltzer tablet into the jar with the ice-cold water (after having removed the ice cubes with a spoon). Again time how long it takes the tablet to disappear. How long does it take the tablet to disappear in the colder water? • Do you notice other differences in how the reaction happens in the colder versus in the hotter water? • Why do you think you got the results you did? • Extra: Test Alka-Seltzer tablets in a wider range of temperatures, and then draw a graph showing the time it takes a tablet to dissolve in water at each temperature (check with a thermometer). What temperature change is required to increase the reaction time by a factor of two (make it as twice as fast)? What about decreasing the reaction time by a factor of two? • Extra : Compare whole Alka-Seltzer tablets to pieces of Alka-Seltzer tablets. If there is a greater surface area (that is, a tablet is broken up into more pieces to expose more surface), does the same amount of tablet result in the reaction happening faster or slower? • Extra : You can turn this activity into a homemade lava lamp! To do this, you will use an empty container, such as a tall jar or clear plastic one- or two-liter bottle. Fill it with about two inches of water, add five drops of food coloring and then fill it at least three quarters full with vegetable oil before adding one quarter of an Alka-Seltzer tablet. You could repeat this activity using your homemade lava lamp at colder and warmer temperatures. (Because it contains oil, you should have an adult help you devise a safe way to warm or cool the contents of each container.) How does the bicarbonate reaction look in the homemade lava lamp? Observations and results Did the Alka-Seltzer tablet dissolve much faster in the hot water compared to the cold? Were there a lot more bubbles produced initially in the hot compared with the cold water?

After the Alka-Seltzer tablet was added to the hot water the tablet should have quickly dissolved, taking some 20 to 30 seconds to do so, depending on the exact temperature. After the tablet was added to the ice-cold water it should have taken much longer to dissolve, with most of the tablet disappearing after about two to three minutes, but with some bubbles still apparent after six minutes or longer. In the hot water the tablet should have more vigorously produced bubbles than in the cold water. The higher the temperature, the faster the molecules move—and the more likely it is that the bicarbonate will contact hydrogen in just the right way for the chemical reaction to occur and produce carbon dioxide bubbles.

More to explore Chemical Reactions , from Rader's Chem4Kids.com Factors Affecting the Speed-Rates of Chemical Reactions , from Doc Brown's Science Rates of Reaction Menu , from Chemguide Plop, Plop, Fizz Fast: The Effect of Temperature on Reaction Time , from Science Buddies

This activity brought to you in partnership with  Science Buddies

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