Factors affecting the rate of reaction

Some factors affect the rates of chemical reactions.

A student investigated the effect of changing the particle size of calcium carbonate on the rate of reaction with hydrochloric acid.

Figure 6 shows the apparatus.

Describe a method the student could use to produce valid results.

The student investigated the effect of increasing the temperature on the rate of a reaction.

Explain the effect of increasing the temperature on the rate of a reaction.

Refer to particles and collisions in your answer.

Catalysts affect the rate of reactions.

What is meant by a ‘catalyst’?

What are catalysts in biological systems called?

Some factors affect the rates of chemical reactions.

A student investigated the effect of changing the particle size of calcium carbonate on the rate of reaction with hydrochloric acid.

Figure 3 shows the apparatus.

Describe a method the student could use to produce valid results.

The student investigated the effect of increasing the temperature on the rate of a reaction.

Explain the effect of increasing the temperature on the rate of a reaction.

Refer to particles and collisions in your answer.

Catalysts affect the rate of reactions.

What is meant by a ‘catalyst’?

What are catalysts in biological systems called?

A catalyst is used to increase the rate of decomposition of hydrogen peroxide.

Hydrogen peroxide decomposes to produce water and oxygen. Write a word equation for the reaction.

A student investigated the rate of decomposition of hydrogen peroxide using three different catalysts:

• manganese dioxide

• copper oxide

• zinc oxide.

Figure 7 shows the apparatus.

This is the method used.

1. Measure 25 cm³ of hydrogen peroxide solution into a flask.

2. Add 0.5 g of manganese dioxide catalyst to the flask.

3. Attach a gas syringe to the flask.

4. Measure the volume of oxygen produced every 20 seconds for 120 seconds.

5. Repeat steps 1 to 4 two more times.

6. Repeat steps 1 to 5 using copper oxide catalyst.

7. Repeat steps 1 to 5 using zinc oxide catalyst.

Which two control variables are used in the investigation? Tick (✓) two boxes.

Table 3 shows the results with manganese dioxide catalyst.

Figure 8 shows a graph of the results with copper oxide catalyst and with zinc oxide catalyst.

Complete Figure 8. You should:

• plot the data for the manganese dioxide catalyst from Table 3

• draw a line of best fit.

The first two points have been plotted for you.

Which is the best catalyst? Give one reason for your answer. Use the completed Figure 8. Tick (✓) one box.

The student repeated the investigation with manganese dioxide catalyst. The results were all close to the true value. Complete the sentence. Choose the answer from the box.

Results that are close to the true value are

The student repeated the investigation using manganese dioxide catalyst at a higher temperature. Complete the sentence. Choose the answer from the box.

A student investigates the effect of concentration on the rate of the reaction between sodium thiosulfate solution and hydrochloric acid.

Figure 6 shows the experiment.

The experiment was done in a fume cupboard.

This is the method used.

1. Pour 50 cm³ of sodium thiosulfate solution into a conical flask.

2. Put the conical flask on a black cross drawn on a piece of paper.

3. Pour 10 cm³ of hydrochloric acid into the conical flask and start a timer.

4. Stop the timer when the cross can no longer be seen.

5. Repeat the experiment with different concentrations of sodium thiosulfate solution.

Draw one line from each type of variable to the correct example of the variable in this investigation.

Type of variable
Example of variable

The experiment is done at room temperature.

What is the temperature shown on the thermometer in Figure 7 ?

Table 1 shows the student’s results.

Plot the data from Table 1 on Figure 8.

Draw a line of best fit.

Predict the time taken for the cross to no longer be seen at a concentration

Use your graph in Figure 8.

Complete the sentence.

As the concentration of sodium thiosulfate solution increases, the time taken for the

In one experiment 0.725 g of sulfur is produced in 20 seconds.

Calculate the mean rate of the reaction from 0 to 20 seconds.

Use the equation:

What is the unit for the mean rate of reaction calculated in Question 04.6 ?

Tick (✓) one box.

The student did the experiment with 0.15 mol/dm³ sodium thiosulfate solution and repeated the experiment three more times.

Table 2 shows the results.

Calculate the mean time for this reaction.

Do not include the anomalous result in your calculation.

Give your answer to 3 significant figures.

A student investigated the reaction between magnesium and excess hydrochloric acid. Figure 5 shows the apparatus.

This is the method used.

1. Pour 50 cm³ of hydrochloric acid into a conical flask.

2. Add a piece of magnesium.

3. Insert stopper and delivery tube and start a timer.

4. Collect the gas produced in a gas syringe.

5. Record the volume of gas produced every 20 seconds for 2 minutes.

6. Repeat steps 1 to 5 with higher concentrations of hydrochloric acid.

Give the independent variable and one control variable in this investigation. Independent variable

Table 3 shows the results from the first experiment using hydrochloric acid with a

low concentration.

Complete Figure 6. You should:

• plot the data from Table 3 (the point 0,0 has been plotted for you)

• draw a line of best fit.

How does the rate of this reaction change with time? Use Table 3. Tick (✓) one box.

The student repeated the experiment using hydrochloric acid with a higher concentration. Which statement is correct? Tick (✓) one box.

Temperature also affects the rate of the reaction. Explain how increasing the temperature affects the rate of the reaction. You should refer to particles and collisions.

Figure 1 shows the apparatus.

This is the method used.

1. Pour 50 cm³ of hydrochloric acid into a conical flask.

2. Add a piece of magnesium.

3. Insert stopper and delivery tube and start a timer.

4. Collect the gas produced in a gas syringe.

5. Record the volume of gas produced every 20 seconds for 2 minutes.

6. Repeat steps 1 to 5 with higher concentrations of hydrochloric acid.

Give the independent variable and one control variable in this investigation.

Independent variable

Table 1 shows the results from the first experiment using hydrochloric acid with a

low concentration.

Complete Figure 2.

You should:

• plot the data from Table 1 (the point 0,0 has been plotted for you)

• draw a line of best fit.

How does the rate of this reaction change with time?

Use Table 1.

Tick (✓) one box.

The student repeated the experiment using hydrochloric acid with a higher concentration.

Which statement is correct?

Tick (✓) one box.

Temperature also affects the rate of the reaction.

Explain how increasing the temperature affects the rate of the reaction.

You should refer to particles and collisions.

This question is about hydrogen peroxide.

The symbol equation for the decomposition of hydrogen peroxide (H₂O₂) is:

Complete the word equation for the decomposition of hydrogen peroxide.

A student investigated the effect of different catalysts on the decomposition of hydrogen peroxide. The student measured the volume of gas collected every 30 seconds for 5 minutes. Figure 5 shows the apparatus used.

Which two variables should the student keep the same to make the investigation a fair test? Tick (✓) two boxes.

Figure 6 shows a gas syringe.

What is the volume of gas in the syringe?

Table 3 shows the student’s results for one catalyst.

Six of the other results have been plotted on Figure 7.

Complete the graph in Figure 7. You should:

• plot the results from Table 3

• draw a line of best fit for all of the results.

The student repeated the experiment with other catalysts and plotted a graph for each of the catalysts used.

Suggest how the student could use these graphs to identify the best catalyst.

All the graphs level off at the same volume of gas. Suggest why.

In another investigation, a student increased the temperature of the hydrogen peroxide. Why is the rate of reaction faster when the temperature of the hydrogen peroxide is increased? Tick (✓) two boxes.

Some students investigated the effect of temperature on the rate of reaction.

The students reacted sodium thiosulfate solution with hydrochloric acid. This is the method used.

1. Use a beaker to measure 50 cm³ of heated sodium thiosulfate solution into a

conical flask.

2. Measure the temperature of the room.

3. Put the conical flask on a black cross drawn on a piece of paper.

4. Start a timer.

5. Use the same beaker to measure 10 cm³ of hydrochloric acid into the conical flask.

6. Stop the timer when the cross is no longer visible.

The students repeated the experiment at a different room temperature. Figure 10 shows the apparatus.

The method contains errors and does not produce accurate results.

Describe a method the students should use to produce accurate results. You do not need to write about safety precautions.

Some students investigated the effect of temperature on the rate of a

different reaction. They recorded the loss of mass from their apparatus at 40 °C Figure 11 shows the results.

Calculate the mean rate of reaction between 1 minute and 3 minutes at 40 °C Use Figure 11 and the equation:

Draw a curve on Figure 11 for the results you would expect at a temperature of

Some students investigated the effect of temperature on the rate of reaction.

The students reacted sodium thiosulfate solution with hydrochloric acid. This is the method used.

1. Use a beaker to measure 50 cm³ of heated sodium thiosulfate solution into a

conical flask.

2. Measure the temperature of the room.

3. Put the conical flask on a black cross drawn on a piece of paper.

4. Start a timer.

5. Use the same beaker to measure 10 cm³ of hydrochloric acid into the conical flask.

6. Stop the timer when the cross is no longer visible.

The students repeated the experiment at a different room temperature. Figure 1 shows the apparatus.

The method contains errors and does not produce accurate results.

Describe a method the students should use to produce accurate results. You do not need to write about safety precautions.

Some students investigated the effect of temperature on the rate of a different reaction. They recorded the loss of mass from their apparatus at 40 °C Figure 2 shows the results.

Calculate the mean rate of reaction between 1 minute and 3 minutes at 40 °C Use Figure 2 and the equation:

Draw a curve on Figure 2 for the results you would expect at a temperature of