Effect of Surface Area on the Rate of Reaction

Scientific Concept

There are many factors that affect the rate of reaction. One of the factors is surface area of

material. The surface area of material will affect the rate of reaction which is slow or fast the

reaction. The effect of surface area can be determined by recording the time taken for the

reaction to occur. The rate of reaction will increase when the surface area of the reactant

increase. In addition, there have two ways in order to find the effect of the surface area of the

rate of reaction. Powder and solid have different surface area which will affect the rate of

reaction. From this we can see that the effect rate of reaction due to the surface area of material.

The rate of reaction using solid

Time(second) 0 ½ 1 3/2 2 5/2 3 6/2 4

Burette reading

(cm3)

50.0 45.5 41.5 38.0 35.0 32.5 30.5 28.0 27.5

Volume of gas

(cm3)

0.0 4.5 8.5 12.0 15.0 17.5 19.5 22.0 22.5

The rate of reaction using powder

Time(second) 0 ½ 1 3/2 2 5/2 3 6/2 4

Burette reading

(cm3)

50.0 42.0 35.0 30.0 25.5 22.0 19.5 17.5 16.0

Volume of gas

(cm3)

0.0 8.0 15.0 20.0 24.5 28.0 30.5 32.5 34.0

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UNIQUE FEATURE OF THIS ACTIVITY

The data can be manipulated easily, for example if the volume of gas is changed (the rate

reaction using powder) at certain time, the amount of gas must higher than the volume of

gas for the rate reaction using solid.

Data displayed in a systematic manner, save time in drawing graphs, show relationship of

different volume of gas powder and solid against time.

Student will discover that a spreadsheet can be used to process data.

Allow the student to do more important things such as analyzing the data or the graph.

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Engage

Dissolving of Salt

You are given two different pictures. Observe the pictures carefully. What will happened when

the substance pour into the water?

What can you observe from the picture?

Which one will dissolve first in the water?

Why there is a different time taken for the salt to dissolve?

How could this happen?

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Rough salt Smooth Salt

Answer

1. There are 2 types of salt that is rough salt and smooth salt. Both of this salt have different

in surface area that will affect their solubility in water.

2. Smooth salt.

3. There have different time taken for the salt to dissolve because of the surface area of the

salt.

4. Smooth salt could easily dissolve in water compare to rough salt because the surface area

of the salt. When the surface area of substance increase, the rate of reaction also increase.

In this case, that was happening on the salt when it was put into the water.

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Empower

1. Students plan an experiment to investigate the effect of surface area to the rate of reaction.

2. They are given the following apparatus:

- Hydrochloric acid solution ( HCl)- Calcium Carbonate (CaCO3) in solid and powder form.-A Conical Flask-A Stopper-A Retort Stand-A Stopwatch-A Beaker- A burette

3. Students are asked to plan an experiment to show that surface area give an effect to the rate of reaction.

4. Students have to construct a hypothesis before doing the experiment.

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Carbon Dioxide gas

Retort Stand

Burette

Calcium Carbonate

Hydrochloric Acid (aq)

Conical Flask

Chanel deliver

Water

5. The procedures of conducting the experiment is discussed before the experiment

i. Fill up the burette with water and place it in the beaker that containing full of water. Record the initial water level in the burette.

ii. Measure 7.0 g of Calcium Carbonate in solid state and pour it in the conical flask.iii. Measure and pour 50 cm3 of 0.2 mol dm-3 hydrochloric acid into the conical flask. At

that time start the stopwatch.iv. Record the level of the water every ½ minutes until 4 minutes.v. Repeat steps 1 until 4 using Calcium Carbonate in powder. Temperature, volume and

concentration of hydrochloric acid are constant.vi. Record the data.

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Results:

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Question:

1. Write a chemical reaction that occurs in this experiment.

2. Which material releases more carbon dioxide (CO2)? Why?

Answers:

1. CaCO3(s) + 2HCl(aq) CaCl2(aq) + H2O(l) + CO2(g)2. Calcium Carbonate in powder. Because smaller materials will give a bigger surface area

to react to the reaction that contribute to higher rate of reaction. This makes the material release more carbon dioxide.

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ENHANCE

More smaller wood used easier the wood to burntThese phenomena related to the affect of surface area to the rate of reaction.

1. What is the meaning of rate of reaction?

2. How does surface area affect a chemical reaction?

3. Rate of reaction between Calcium carbonate with Hydrochloric acid can be determined by:

i. ……………………………………..

ii. …………………………………….

4. What are other factors that affect the rate of reaction?

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Answer

1. The rate of a reaction is the speed at which a reaction happens. If a reaction has a low

rate, that means the molecules combine at a slower speed than a reaction with a high rate.

2. If one of the reactants is a solid, the surface area of the solid will affect how fast the

reaction goes. This is because the two types of molecule can only bump into each other at

the liquid solid interface, i.e. on the surface of the solid. So the larger the surface area of

the solid, the faster the reaction will be. Smaller particles have a bigger surface area than

larger particle for the same mass of solid.

There is a simple way to visualize this. Take a loaf of bread and cut it into slices. Each

time you cut a new slice, you get an extra surface onto which you can spread butter and

jam. The thinner you cut the slices, the more slices you get and so the more butter and

jam you can put on them. This is "Bread and Butter Theory". In the other idea, by

chewing your food, you increase the surface area so that digestion can go faster.

3. i. Rate of reducing mass of Calcium carbonate.

ii. Rate of releasing Carbon dioxide.

4. Concentration, temperature and catalyst.

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