Rate of reaction

A student investigated the reactivity of four metals with sulfuric acid.

Figure 13 shows the apparatus.

Give two variables the student should control.

Write the order of reactivity from least reactive to most reactive for the four metals.

Use Figure 13.

The gas produced in Figure 13 is hydrogen.

Describe the test for hydrogen gas.

Give the result if hydrogen is present.

The student repeated the investigation using different apparatus to determine the rate of reaction.

Figure 14 shows part of the apparatus.

Complete Figure 14 so that the apparatus can be used to determine the rate of reaction.

Give two measurements the student should make to determine the rate of reaction.

What is the unit for the rate of reaction determined using the apparatus in Figure 14

A student investigated the reactivity of four metals with sulfuric acid.

Figure 5 shows the apparatus.

Give two variables the student should control.

Write the order of reactivity from least reactive to most reactive for the four metals.

Use Figure 5.

The gas produced in Figure 5 is hydrogen.

Describe the test for hydrogen gas.

Give the result if hydrogen is present.

The student repeated the investigation using different apparatus to determine the rate of reaction.

Figure 6 shows part of the apparatus.

Complete Figure 6 so that the apparatus can be used to determine the rate of reaction.

Give two measurements the student should make to determine the rate of reaction.

What is the unit for the rate of reaction determined using the apparatus in Figure 6?

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

The word equation for the reaction is:

calcium carbonate + hydrochloric acid calcium chloride + water + carbon dioxide

Figure 6 shows the apparatus.

This is the method used.

1. Add 50 cm³ of hydrochloric acid to the conical flask.

2. Add 2.0 g of calcium carbonate to the conical flask.

3. Immediately insert the stopper into the conical flask and start the timer.

4. Record the volume of gas collected in the gas syringe every 30 seconds.

5. Stop recording when the volume of gas in the gas syringe does not change.

Which piece of equipment is the most suitable to measure the volume of hydrochloric acid?

Tick (✓) one box.

Beaker

Measuring cylinder

Test tube

Name one piece of equipment that can be used to measure the mass of calcium carbonate.

Why must the stopper be inserted immediately after the reactants are added to the flask?

Figure 7 shows the results.

Describe the trend for the volume of gas collected.

Use Figure 7.

Determine the mean rate of reaction from 0 to 30 seconds.

Use Figure 7.

Use the equation:

Choose the unit from the box.

What is the minimum amount of energy that particles must have to react?

Tick (✓) one box.

Activation energy

Kinetic energy

Potential energy

A student investigated the reaction between calcium carbonate and hydrochloric acid.

The equation for the reaction is:

The student investigated the effect of changing the concentration of hydrochloric acid on the rate of the reaction.

Figure 16 shows the apparatus.

This is the method used.

1. Add 50 cm³ of hydrochloric acid to the conical flask.

2. Add 2.0 g of calcium carbonate to the conical flask.

3. Immediately insert the stopper into the conical flask and start the timer.

4. Record the volume of gas collected in the gas syringe every 30 seconds.

5. Stop recording when the volume of gas in the gas syringe does not change.

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

Name the independent variable in this investigation.

Figure 17 shows the results for one concentration of hydrochloric acid.

Enlarge

How does Figure 17 show that the rate of reaction decreases with time?

Explain why the rate of reaction between calcium carbonate and hydrochloric acid decreases with time.

Calcium carbonate reacts with hydrochloric acid.

The word equation for the reaction is:

calcium carbonate + hydrochloric acid → calcium chloride + water + carbon dioxide

A student investigated the effect of changing the surface area of the calcium carbonate on the rate of this reaction.

The student changed the surface area of the calcium carbonate by using different-sized lumps.

Figure 6 shows the apparatus.

The rate of reaction is determined by measuring the decrease in mass of the conical flask and contents at regular time intervals.

This is the method used.

1. Place a conical flask on a balance.

2. Add 50 cm³ of hydrochloric acid to the conical flask.

3. Add 2 g of small lumps of calcium carbonate to the hydrochloric acid.

4. Put cotton wool in the top of the conical flask.

5. Record the mass every 60 seconds until the mass remains constant.

6. Repeat steps 1 to 5 with 2 g of large lumps of calcium carbonate.

Why was cotton wool put in the top of the conical flask?

Tick (✓) one box.

To slow down the reaction

To stop acid splashing out of the conical flask

To stop carbon dioxide gas escaping

What was the independent variable in this investigation?

Give one control variable used in this investigation.

Table 3 shows some of the results.

Calculate the mean rate of reaction from 0 to 60 seconds for the small lumps.

Use the equation:

Use Table 3.

Complete Figure 7.

You should:

label the y-axis

plot the data from Table 3 as a bar chart

label each bar.

Why are the results plotted as a bar chart and not as a line graph?

Table 3 is repeated below.

What effect does the size of the calcium carbonate lumps have on the rate of reaction?

Use Table 3.

Tick (✓) one box.

Increasing the size of the lumps decreases the rate of reaction.

Increasing the size of the lumps does not affect the rate of reaction.

Increasing the size of the lumps increases the rate of reaction.

The surface area of a calcium carbonate lump can be estimated by comparing the lump with a cube.

Figure 8 shows a cube and a similar-sized calcium carbonate lump.

Figure 8

Enlarge

Suggest one reason why the total surface area of the lump in Figure 8 is estimated rather than measured.

Calcium carbonate reacts with hydrochloric acid.

The equation for the reaction is:

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

A student investigated the effect of changing the surface area of the calcium carbonate on the rate of this reaction.

The student used calcium carbonate in the form of lumps and of powder.

Figure 4 shows the apparatus.

The rate of reaction is determined by measuring the decrease in mass of the conical flask and contents at regular time intervals.

Give the reason why the mass of the conical flask and contents decreases.

The mean rate of reaction using the calcium carbonate lumps was 0.0012 g/s.

Calculate the time taken for the mass of the conical flask and contents to decrease by 0.36 g.

The results showed that calcium carbonate powder reacted faster than calcium carbonate lumps.

Explain why calcium carbonate powder reacted faster than calcium carbonate lumps.

The surface area of a calcium carbonate lump can be estimated by comparing the lump with a cube.

Figure 5 shows a cube and a similar-sized calcium carbonate lump.

Figure 5

Calculate the total surface area of the cube in Figure 5.

Total surface area = cm² ________________

The total surface area of the calcium carbonate lump in Figure 5 is estimated rather than measured.

Suggest one reason why.

Magnesium reacts with hydrochloric acid.

A student investigated the effect of changing the hydrochloric acid concentration on the rate of this reaction.

Figure 22 shows the apparatus.

This is the method used.

1. Add 50 cm³ of hydrochloric acid to the conical flask.

2. Add a 3 cm strip of magnesium to the hydrochloric acid in the conical flask.

3. Fit the stopper and delivery tube to the top of the conical flask and start timing.

4. Record the volume of hydrogen gas collected in the measuring cylinder every 20 seconds for a total of 100 seconds.

5. Repeat steps 1 to 4 with a different concentration of hydrochloric acid.

The stopper and delivery tube were fitted to the conical flask in step 3.

Explain why the time taken to fit the stopper and delivery tube may cause an error in this investigation.

Figure 23 shows the results for one concentration of hydrochloric acid.

Determine the time taken for the reaction to be complete.

Use Figure 23.

The student repeated the method using a higher concentration of hydrochloric acid.

How would the line of best fit for a higher concentration of hydrochloric acid compare with the line of best fit on Figure 23 ?

Tick (✓) one box.

Initially the line of best fit would have a lower gradient.

Initially the line of best fit would have the same gradient.

Initially the line of best fit would have a higher gradient.

Describe the test for hydrogen gas.

Give the result of the test.

Magnesium reacts with hydrochloric acid.

A student investigated the effect of changing the hydrochloric acid concentration on the rate of this reaction.

Figure 2 shows the apparatus.

This is the method used.

1. Add 50 cm³ of hydrochloric acid to the conical flask.

2. Add a 3 cm strip of magnesium to the hydrochloric acid in the conical flask.

3. Fit the stopper and delivery tube to the top of the conical flask and start timing.

4. Record the volume of hydrogen gas collected in the measuring cylinder every 20 seconds for a total of 100 seconds.

5. Repeat steps 1 to 4 with a different concentration of hydrochloric acid.

The stopper and delivery tube were fitted to the conical flask in step 3.

Explain why the time taken to fit the stopper and delivery tube may cause an error in this investigation.

Figure 3 shows the results for one concentration of hydrochloric acid.

Determine the time taken for the reaction to be complete.

Use Figure 3.

The student repeated the method using a higher concentration of hydrochloric acid.

How would the line of best fit for a higher concentration of hydrochloric acid compare with the line of best fit on Figure 3 ?

Tick (✓) one box.

Initially the line of best fit would have a lower gradient.

Initially the line of best fit would have the same gradient.

Initially the line of best fit would have a higher gradient.

Describe the test for hydrogen gas.

Give the result of the test.

This question is about the reaction between copper carbonate and nitric acid.

Carbon dioxide is produced when copper carbonate reacts with nitric acid.

Give the test for carbon dioxide gas.

Give the result of the test if carbon dioxide is present.

The word equation for the reaction between copper carbonate and nitric acid is:

copper carbonate + nitric acid X + Y + carbon dioxide

Name the products X and Y.

A student investigated the rate of the reaction between copper carbonate and nitric acid.

Describe a method to show the effect of changing the temperature of the nitric acid on the rate of reaction.

Your method should include measuring the volume of carbon dioxide gas produced.

The student concluded that:

‘An increase in temperature increases the rate of reaction.’

The student’s conclusion was correct.

Explain why an increase in temperature increases the rate of reaction.

You should refer to particles and collisions in your answer.

A student investigated the rate of the reaction between sodium thiosulfate solution and hydrochloric acid.

The equation for the reaction is:

Sulfur dioxide causes respiratory problems.

Suggest one precaution to reduce the risk of respiratory problems for the student.

This is the method used.

1. Add 50 cm³ of sodium thiosulfate solution to a conical flask.

2. Put the conical flask on a piece of paper marked with a cross.

3. Add 5 cm³ of hydrochloric acid and start timing with a stopclock.

4. Swirl the conical flask.

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

6. Repeat steps 1 to 5 for different concentrations of sodium thiosulfate solution.

Figure 3 shows the apparatus used.

Explain why the cross is no longer visible.

Use the equation for the reaction to help you.

Suggest one change to the method that would improve the accuracy of the results.

Give one reason why the change would improve the accuracy.

Table 3 shows the results.

Plot the data from Table 3 on Figure 4.

Draw a line of best fit.

Predict the time taken for the cross to be no longer visible for a 48 g/dm³ sodium thiosulfate solution.

Use Figure 4.

Give one conclusion about the effect of changing the concentration of sodium thiosulfate solution on the rate of reaction.

This question is about hydrogen peroxide.

The formula of hydrogen peroxide is H₂O₂

Name the elements in a molecule of hydrogen peroxide.

How many atoms are in a molecule of hydrogen peroxide?

Hydrogen peroxide decomposes to produce oxygen and water.

Write the word equation for the reaction.

A student investigated the decomposition of hydrogen peroxide.

The student used manganese dioxide as a catalyst.

The student measured the volume of oxygen produced.

The student collected the oxygen in a gas syringe.

Figure 7 shows a gas syringe.

What is the volume of oxygen in the syringe?

Figure 8 shows how the volume of oxygen collected varied with time.

Which point on Figure 8 shows when the reaction is fastest?

Tick (✓) one box.

Which point on Figure 8 shows when the reaction has stopped?

Tick (✓) one box.

The student repeated the investigation using raw potato instead of manganese dioxide.

An enzyme in the potato acts as the catalyst.

Draw one line from each catalyst to the type of substance the catalyst is.

The student repeated the investigation using boiled potato instead of raw potato.

The enzyme in the boiled potato did not catalyse the reaction.

How will the rate of decomposition of hydrogen peroxide using boiled potato compare with the rate using raw potato?

Tick (✓) one box.

Hydrogen peroxide (H₂O₂) decomposes to produce oxygen gas and water.

Balance the equation for the reaction.

Two catalysts that can be used in the reaction are raw potato and

manganese dioxide.

A student compared the rate of decomposition of hydrogen peroxide using:

• a cube of raw potato as the catalyst

• crushed raw potato as the catalyst.

The student kept all other variables constant.

The hydrogen peroxide decomposed at a different rate when using a cube of raw potato compared with using crushed raw potato.

Explain why.

The student repeated the investigation using boiled potato instead of raw potato.

When boiled potato is added to hydrogen peroxide no bubbles of oxygen are observed.

Explain why.

The student then investigated the rate of decomposition of hydrogen peroxide using manganese dioxide as the catalyst.

The student measured the volume of oxygen produced every 5 seconds for 50 seconds.

Figure 12 shows the results.

Determine the rate of reaction at 15 s

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

The reaction produced a gas.

Which gas is produced in the reaction?

Tick (✓) one box.

Figure 1 shows the apparatus used.

What is the piece of equipment labelled A ?

Tick (✓) one box.

The student saw that a chemical reaction was taking place.

Give two observations that would show a chemical reaction was taking place.

At the start of the investigation the volume of gas in the measuring cylinder was zero.

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

The readings for the volume of gas were 24 cm³, 44 cm³, 59 cm³, 70 cm³, 76 cm³ and 79 cm³

Complete Table 1.

How could the student make the reaction faster?

Tick (✓) one box.

The student repeated the investigation at a higher temperature.

Figure 2 shows the results.

Determine the mean rate of reaction for the first 10 seconds.

Use the equation:

Give the unit.

Choose the unit from the box.

Determine the time at which the reaction finished and no more gas was produced.

Use Figure 2.

Why does the rate of reaction increase when the temperature is higher?

Tick (✓) two boxes.

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

The student measured the volume of hydrogen gas produced.

How could the student collect and measure the volume of gas produced?

At the start of the investigation the volume of gas was 0 cm³

The student took readings at 20-second intervals.

Readings for the volume of gas were 24 cm³, 44 cm³, 59 cm³, 70 cm³, 76 cm³ and 79 cm³

Draw a results table for the investigation.

Include the student’s results in the table.

The student repeated the investigation at a higher temperature.

Figure 7 shows the results.

Determine the rate of reaction at 30 seconds.

Show your working on Figure 7.

Give your answer to 2 significant figures.

The rate of reaction increases at higher temperatures.

Explain why.

Answer in terms of particles.

A student investigated the rate of reaction of magnesium with dilute hydrochloric acid.

This is the method used.

1. Add 50 cm³ of dilute hydrochloric acid to a conical flask.

2. Add 0.2 g of magnesium ribbon to the dilute hydrochloric acid in the conical flask.

3. Attach a gas syringe to the conical flask.

4. Record the volume of gas in the gas syringe every 10 seconds.

Figure 5 shows the student’s results.

Calculate the mean rate of reaction in the first 10 seconds.

Use Figure 5 and the equation:

What is the unit for the mean rate of the reaction calculated in Question 05.1 ?

Tick one box.

Give two conclusions you can make about the reaction from 90 s to 120 s

Use Figure 5.

The student repeated the method using magnesium powder instead of magnesium ribbon. All other variables were kept the same.

What is the independent variable in the investigation?

Tick one box.

Sketch a line on Figure 5 to show the expected results for the experiment using