Rate of reaction

A student investigated the reaction of calcium carbonate with hydrochloric acid.

Figure 2 shows the apparatus.

This is the method used.

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

2. Add 4.0 g of calcium carbonate to the conical flask.

3. Insert the stopper into the conical flask as quickly as possible.

4. Start a timer.

5. Measure the volume of gas collected every 30 seconds for 3 minutes.

6. Repeat steps 1 to 5 using different concentrations of hydrochloric acid.

Name a suitable piece of equipment to measure 4.0 g of calcium carbonate.

Figure 3 shows the gas syringe during the investigation.

What is the reading on the gas syringe?

What is the independent variable in the investigation?

Tick () one box.

Why did the student insert the stopper into the conical flask as quickly as possible in step 3?

The gas produced during the investigation is carbon dioxide.

The test for carbon dioxide uses limewater.

What is the chemical name for limewater?

Tick () one box.

The student measured the volume of gas collected every 30 seconds for 3 minutes.

The volume of gas was zero at the start.

For one concentration of hydrochloric acid, the volumes of gas collected were:

Complete Table 3.

You should:

• add headings to each column

• add units

• add all of the results to the table.

The student used a different concentration of hydrochloric acid.

18 cm³ of gas was collected in the first 30 seconds.

Calculate the mean rate of reaction for the first 30 seconds.

Use the equation:

Choose the unit from the box.

Increasing the concentration of hydrochloric acid increases the rate of the reaction.

What are two reasons why?

Tick () two boxes.

Students investigated the effect of changing the concentration on the rate of chemical reactions.

A student reacted sodium thiosulfate solution with hydrochloric acid.

Figure 3 shows the apparatus.

This is the method used.

1. Measure 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. Add 10 cm³ of hydrochloric acid to the conical flask.

4. Start a timer.

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

6. Record the time taken.

7. Repeat steps 1 to 6 using different concentrations of sodium thiosulfate solution.

What is the dependent variable in this investigation?

The equation for the reaction is:

Na₂S₂O₃(aq) + 2 HCl(aq) → 2 NaCl(aq) + S(s) + SO₂(g) + H₂O(l)

The mixture becomes cloudy as the reaction takes place.

Explain why the mixture becomes cloudy.

Explain the effect of changing the concentration of the sodium thiosulfate solution on the rate of reaction.

A different student reacted magnesium with hydrochloric acid.

Figure 4 shows the apparatus.

This is the method used.

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

2. Add 0.1 g of magnesium ribbon to the conical flask.

3. Insert the stopper into the conical flask as quickly as possible.

4. Start a timer.

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

6. Repeat steps 1 to 5 using different concentrations of hydrochloric acid.

Why is the stopper inserted into the conical flask as quickly as possible in step 3?

The equation for the reaction of magnesium with hydrochloric acid is:

Describe a test for the gas produced in the reaction.

Give the result of the test.

Figure 5 shows the results for one concentration of hydrochloric acid.

Determine the rate of reaction at 75 seconds.

Sulfuric acid is produced by an industrial process.

In the process, sulfur dioxide (SO₂) reacts with oxygen (O₂) to produce

The equation for the reversible reaction is:

The forward reaction releases 198 kJ/mol of energy.

What is the amount of energy transferred during the reverse reaction?

Tick () one box.

The concentration of oxygen is increased.

What is the effect on the position of the equilibrium?

Tick () one box.

The pressure is decreased.

What is the effect on the position of the equilibrium?

Tick () one box.

The temperature is increased.

What is the effect on the position of the equilibrium?

Tick () one box.

A catalyst is used in the reaction.

Suggest what effect the catalyst has on the position of the equilibrium.

Give one reason for your answer.

A scientist measured how the number of moles of sulfur dioxide, oxygen and

sulfur trioxide varied with time during the reaction.

Figure 5 shows the results.

Determine the time taken for the reaction to reach equilibrium.

Explain your answer.

Use Figure 5.

Figure 6 shows the results for sulfur trioxide.

Determine the rate of reaction at 60 seconds.

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

• manganese dioxide

• copper oxide

• zinc oxide.

Figure 2 shows the apparatus.

This is the method used.

1. Measure 20 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 30 seconds for 180 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.

The equation for the decomposition of hydrogen peroxide is:

Describe a test to identify the gas produced in the reaction.

Using 10 cm³ of hydrogen peroxide solution gives less accurate results than using 20 cm³ of hydrogen peroxide solution of the same concentration. Explain why.

Suggest one possible source of systematic error in the investigation.

Table 3 shows the results for manganese dioxide catalyst.

Figure 3 shows a graph of the results with copper oxide catalyst and with zinc oxide catalyst.

Complete Figure 3. You should:

• plot the data from Table 3

• draw a line of best fit.

The first point has been plotted for you.

Which catalyst gives the fastest rate of reaction? Give one reason for your answer. Use the completed Figure 3.

The rate of reaction is not dependent on the volume of hydrogen peroxide solution. Explain why.

Figure 4 shows the results from a different investigation.

Determine the rate of reaction at 20 seconds. Show your working on Figure 4. Give your answer to 3 significant figures.

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.

This question is about the reaction between sodium thiosulfate solution and hydrochloric acid. The equation for the reaction is:

The mass of the conical flask and contents was greater at the start of the reaction than at the end. Explain why.

A teacher demonstrated the reaction between sodium thiosulfate solution and hydrochloric acid. Figure 3 shows the experiment. The experiment was done in a fume cupboard.

This is the method the teacher 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 at different temperatures.

What type of variable is time in this reaction? Tick (✓) one box.

Table 1 shows the results.

Complete Figure 4. You should:

• plot the data from Table 1 on Figure 4

• draw a line of best fit.

A student investigated the effect of concentration of sodium thiosulfate on the time taken for the reaction at room temperature. Figure 5 shows the results with a tangent drawn at 0.4 mol/dm³

Calculate the gradient (slope) of the tangent at 0.4 mol/dm³ Give the unit.

The student determined the rate of the reaction at regular time intervals during an experiment. Explain why the rate decreased during the reaction. You should give your answer in terms of particles.

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

A student investigated the rate of the reaction between magnesium and hydrochloric acid.

Figure 4 shows the apparatus the student used.

Balance the equation for the reaction.

The student used 50 cm³ of hydrochloric acid.

Which apparatus would measure 50 cm³ of hydrochloric acid with the greatest accuracy?

Tick (✓) one box.

The student measured the volume of gas produced every 20 seconds for 2 minutes.

The volume of gas was zero at the start of the experiment.

The measured volumes of gas were:

Complete Table 2 to show these results.

The volumes of gas were lower than expected.

Suggest one reason.

The student repeated the experiment using different concentrations of hydrochloric acid.

Give two variables the student should keep the same.

Complete the sentences.

As the concentration of the hydrochloric acid increased, the

This question is about magnesium. A student investigated the rate of the reaction between magnesium and hydrochloric acid. Figure 2 shows the apparatus.

Which is the correct ionic equation for the reaction? Tick (✓) one box.

What happens in the reaction between magnesium and hydrochloric acid? Tick (✓) one box.

Table 2 shows the student’s results.

Plot the data from Table 2 on Figure 3. Draw a line of best fit.

Describe the changes in the rate of this reaction.

Explain why the rate of this reaction changes. Give your answer in terms of collision theory.

A student investigated the effect of the size of marble chips on the rate of the reaction between marble chips and hydrochloric acid.

This is the method used.

1. Add 10.0 g of marble chips into the flask.

2. Add 50 cm³ of hydrochloric acid and start a timer.

3. Record the mass lost from the flask every 10 seconds.

4. Repeat steps 1 to 3 with different sizes of marble chips.

Figure 10 shows the apparatus.

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

The equation for the reaction is:

CaCO₃(s) + 2HCl(aq) CaCl₂(aq) + H₂O(l) + CO₂(g)

Name the three products.

Another student suggests putting some cotton wool in the top of the flask.

Suggest why this improves the investigation.

The reaction produces 1.6 g of gas in 30 seconds.

Calculate the mean rate of the reaction in the first 30 seconds.

Use the equation:

What is the unit for the mean rate of reaction calculated in question 05.4 ?

Tick one box.

Table 5 shows the student’s results.

Plot the data from Table 5 on Figure 11

Draw a line of best fit.

Figure 12 shows a large marble chip and eight small marble chips.

The large marble chip has the same total volume as the eight small marble chips, but a different surface area.

Why do the eight small marble chips react faster than the large marble chip?

Tick one box.

A student investigated the effect of the size of marble chips on the rate of the reaction between marble chips and hydrochloric acid. This is the method used.

1. Add 10 g of marble chips into the flask.

2. Add 50 cm³ of hydrochloric acid, connect the gas syringe and start a timer.

3. Record the volume of gas produced every 10 seconds.

Figure 4 shows the apparatus.

Complete the equation for the reaction.

Figure 5 shows the student’s results.

Describe the trend shown in Figure 5 Use values in your answer.

Describe how you would use Figure 5 to find the rate of the reaction at 15 seconds. You do not need to do a calculation.

Give the units for the rate of this reaction.

Table 3 shows the results of the investigation.

Give one conclusion about how the size of the marble chips affects the rate of the reaction.

Suggest why all three sizes of marble chips produce a maximum volume of 60 cm³ of gas.

Figure 6 shows eight small cubes, each 1 cm x 1 cm x 1 cm, and one large cube, 2 cm x 2 cm x 2 cm

Total volume of small cubes = 8 cm³ Volume of large cube = 8 cm³ Total surface area of small cubes = 48 cm²

Calculate the surface area of the large cube.

Explain why the size of the marble chips affects the rate of the reaction. Give your answer in terms of ‘collision theory’.

The student repeated the investigation with small marble chips using hydrochloric acid with a lower concentration. Figure 7 shows the volume of gas produced during the first 40 seconds.

Explain why the results for the lower concentration of acid are different from the results for the higher concentration of acid.