Factors affecting the rate of reaction

This question is about copper and copper compounds.

A teacher demonstrated the reaction of copper with silver nitrate.

Figure 16 shows the apparatus:

at the start

after a few minutes.

The word equation for the reaction is:

solution solution

What type of reaction happens between copper and silver nitrate?

Tick () one box.

Combustion

Displacement

Neutralisation

Give two observations that can be made when copper reacts with silver nitrate solution.

Use Figure 16 and the word equation.

Copper reacted with silver nitrate solution.

The teacher then added copper to nickel nitrate solution.

Copper did not react with nickel nitrate solution.

Write the order of reactivity for copper, nickel and silver.

A student reacted solid copper oxide with nitric acid to produce a solution of copper nitrate.

This is the method used.

1. Add 25 cm³ of nitric acid to a beaker.

2. Warm the nitric acid.

3. Add solid copper oxide to the nitric acid.

4. Stir the mixture.

5. Repeat steps 3 and 4 until solid copper oxide is in excess.

Give one safety precaution the student should use.

The nitric acid was warmed in step 2 of the method.

Suggest how the reaction was affected by warming the nitric acid.

After the reaction finished, the beaker contained a mixture of solid copper oxide and copper nitrate solution.

Describe a method to obtain pure, dry copper nitrate crystals from the mixture.

A student investigated how the surface area of magnesium affects the rate of the reaction between magnesium and hydrochloric acid.

Figure 11 shows the apparatus.

This is the method used.

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

2. Add 0.05 g of magnesium ribbon to the hydrochloric acid.

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

4. Start a stopclock.

5. Record the volume of gas collected in the gas syringe every 20 seconds for 100 seconds.

6. Repeat steps 1 to 5 with 0.05 g of magnesium powder.

Magnesium reacts with hydrochloric acid to produce magnesium chloride and hydrogen.

Balance the equation for the reaction.

What was the independent variable in the investigation?

Tick () one box.

Surface area of magnesium

Time interval

Volume of hydrochloric acid

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

Figure 12 shows the results for magnesium ribbon.

Explain the trend for the volume of gas collected after 80 seconds.

Use Figure 12.

Figure 13 shows the results for magnesium ribbon.

The student then used 0.05 g of magnesium powder instead of 0.05 g of magnesium ribbon.

Draw a line on Figure 13 to show the expected results for the magnesium powder.

A student investigated how the surface area of magnesium affects the rate of the reaction between magnesium and hydrochloric acid.

Figure 6 shows the apparatus.

This is the method used.

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

2. Add 0.07 g of magnesium ribbon to the hydrochloric acid.

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

4. Start a stopclock.

5. Record the volume of gas collected in the gas syringe every 15 seconds for 90 seconds.

6. Repeat steps 1 to 5 with 0.07 g of magnesium powder.

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

Give one control variable in the investigation.

Why do some variables in an investigation need to be controlled?

Tick () one box.

To ensure the investigation is valid.

To make the investigation safe.

To prevent a systematic error.

Table 1 shows the results for magnesium ribbon.

Plot the data from Table 1 on Figure 7.

Draw a line of best fit.

Explain how the rate of reaction would be affected by using magnesium powder instead of magnesium ribbon.

A student investigated the reaction between citric acid powder and sodium hydrogen carbonate solution.

The temperature of the reaction mixture decreased.

Plan a method to investigate how changing the mass of citric acid affects the lowest temperature reached by the mixture.

The reaction between citric acid and sodium hydrogen carbonate is endothermic.

Which reaction profile represents an endothermic reaction?

Tick (✓) one box.

Explain why the rate of reaction is greater when powder is used instead of larger lumps.

Refer to surface area and collisions in your answer.

A student investigated the reaction between citric acid powder and sodium hydrogen carbonate solution.

The temperature of the reaction mixture decreased.

The reaction between citric acid and sodium hydrogen carbonate is endothermic.

Which reaction profile represents an endothermic reaction?

Tick (✓) one box.

Explain why the rate of reaction is greater when powder is used instead of larger lumps.

Refer to surface area and collisions in your answer.

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.

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 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 reactions of metals.

A piece of magnesium reacts with dilute hydrochloric acid.

Magnesium chloride solution and a gas are produced.

Which gas is produced?

Tick (✓) one box.

Chlorine

Hydrogen

Oxygen

Give two observations seen during the reaction.

Magnesium chloride is formed from Mg²⁺ ions and Cl^‒ ions.

What is the formula of magnesium chloride?

Tick (✓) one box.

MgCl MgCl₂ Mg₂Cl Mg₂Cl₂

Calcium is in the same group as magnesium in the periodic table.

What is the symbol for a calcium ion?

Tick (✓) one box.

Ca⁺ Ca^‒ Ca²⁺ Ca^2‒

Figure 2 shows a cube of calcium.

How would you calculate the total surface area of this cube?

Tick (✓) one box.

Total surface area = 2 × 2 × 2

Total surface area = 2 × 2 × 4

Total surface area = 2 × 2 × 6

Total surface area = 2 × 4 × 6

A teacher investigated the reaction between calcium and water.

The teacher used the same mass of three different forms of calcium.

The different forms of calcium were: powder small lumps large lumps.

The teacher measured the time for each reaction to be complete.

What is the independent variable in the investigation?

Tick (✓) one box.

Form of calcium

Mass of calcium

Time for reaction to be complete

Which form of calcium will react the fastest?

Tick (✓) one box.

Powder

Small lumps

Large lumps

Which is the best way to display the results for the three different forms of calcium?

Tick (✓) one box.

Bar chart

Line graph

Pie chart

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.

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.

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