Tests for gases

This question is about unsaturated hydrocarbons.

Table 6 shows the boiling points of some unsaturated hydrocarbons.

Estimate the boiling point X in Table 6.

C₂H₄ reacts with water vapour (steam).

Name the compound produced when C₂H₄ reacts with water vapour.

C₄H₈ reacts with chlorine (Cl₂).

Describe the test for chlorine.

Give the result of the test.

Which is the displayed formula of the organic compound produced when C₄H₈ reacts with chlorine?

Tick (✓) one box.

Name the unsaturated hydrocarbon with the formula C₃H₆

Why does C₃H₆ tend to burn in air with a smoky flame?

C₃H₆ is a gas at room temperature and pressure.

Calculate the volume of 2.1 g of C₃H₆ at room temperature and pressure.

Give your answer in cm³.

The volume of one mole of any gas at room temperature and pressure is 24 dm³.

Relative atomic masses (A_r): H = 1 C = 12

A student analysed three solutions, A, B and C.

Each solution contained one ionic compound.

The student added a few drops of sodium hydroxide solution to solution A.

Solution A produced a white precipitate.

Aluminium ions produce a white precipitate with a few drops of sodium hydroxide solution.

Name one other metal ion which produces a white precipitate with a few drops of sodium hydroxide solution.

Describe how the student could confirm the presence of aluminium ions in solution A

Give the result of the test.

The student tested solution B to identify the ions present.

The student did a flame test on solution B.

An orange-red flame was produced.

Write the symbol for the metal ion in solution B.

The student added dilute nitric acid followed by silver nitrate solution to solution B.

A white precipitate was produced.

Write the symbol for the non-metal ion in solution B.

The student added 1.0 mol/dm³ nitric acid to solution C.

Bubbles of gas were produced.

Describe a test on the bubbles of gas that confirms that solution C contained carbonate ions.

Give the result of the test.

The student repeated the test on solution C using 1.0 mol/dm³ ethanoic acid instead of 1.0 mol/dm³ nitric acid.

Bubbles of gas were produced more slowly using ethanoic acid.

Explain why.

This question is about addition reactions.

Figure 7 shows the displayed structural formula of ethene.

Complete the sentence.

When bromine water is added to ethene, the bromine water changes from orange to

Chlorine reacts with ethene.

What is used to identify chlorine?

Tick (✓) one box.

Which of the following shows the displayed structural formula of the compound produced when chlorine reacts with ethene?

Use Figure 7.

Tick (✓) one box.

Chloroethene can be used to produce a polymer called poly(chloroethene).

The displayed structural formula of chloroethene is

Which represents the structure of poly(chloroethene)?

Tick (✓) one box.

Ethene can be used to produce another polymer called poly(ethene).

Table 3 shows information about poly(chloroethene) and poly(ethene).

Determine the simplest whole number ratio of the density of poly(chloroethene): density of poly(ethene).

Simplest whole number ratio =

Poly(ethene) and poly(chloroethene) can both be used to make pipes.

Suggest why neither polymer is suitable for pipes carrying steam at a temperature of 300 °C.

Use Table 3.

Poly(ethene) and paper can both be used to make shopping bags.

Poly(ethene) is produced from crude oil. Paper is produced from trees.

Suggest one reason why paper is more sustainable than poly(ethene) for making shopping bags.

This question is about ammonia and nitric acid.

In the Haber process ammonia is produced from nitrogen and hydrogen.

Figure 10 represents the Haber process.

Pipe P links the condenser to the reactor.

Why is the condenser linked to the reactor?

Use Figure 10.

Which metal is used as a catalyst in this reaction?

Nitric acid is produced by reacting ammonia with oxygen.

The word equation for the production of nitric acid is:

ammonia + oxygen → water + nitric acid

Platinum is a catalyst in this reaction.

Describe the test for oxygen gas.

Give the result if oxygen gas is present.

Figure 11 represents the reaction profile of the catalysed reaction between ammonia and oxygen.

Complete the reaction profile for the catalysed reaction in Figure 11.

You should:

label the activation energy

label the reactants and products, using the names of the reactants and products.

How would Figure 11 be different if no catalyst was used?

Tick (✓) one box.

Ammonia and nitric acid react to produce the salt, ammonium nitrate.

Ammonium ions and nitrate ions both contain nitrogen.

Suggest one use of ammonium nitrate.

This question is about ammonia and nitric acid.

In the Haber process ammonia is produced from nitrogen and hydrogen.

Figure 1 represents the Haber process.

Pipe P links the condenser to the reactor.

Why is the condenser linked to the reactor?

Use Figure 1.

Which metal is used as a catalyst in this reaction?

Nitric acid is produced by reacting ammonia with oxygen.

The word equation for the production of nitric acid is:

ammonia + oxygen → water + nitric acid

Platinum is a catalyst in this reaction.

Describe the test for oxygen gas.

Give the result if oxygen gas is present.

Figure 2 represents the reaction profile of the catalysed reaction between ammonia and oxygen.

Complete the reaction profile for the catalysed reaction in Figure 2.

You should:

label the activation energy

label the reactants and products, using the names of the reactants and products.

How would Figure 2 be different if no catalyst was used?

Tick (✓) one box.

Ammonia and nitric acid react to produce the salt, ammonium nitrate.

Ammonium ions and nitrate ions both contain nitrogen.

Suggest one use of ammonium nitrate.

A student investigated the rate of the reaction between zinc and sulfuric acid.

The equation for the reaction is

Figure 10 shows the apparatus.

This is the method used.

1. Pour 50 cm³ of sulfuric acid into the conical flask.

2. Add excess zinc to the conical flask.

3. Insert the stopper and start a timer.

4. Measure the volume of hydrogen collected in the 50 cm³ measuring cylinder every 20 seconds for 180 seconds.

Explain why the volume of hydrogen collected in the 50 cm³ measuring cylinder is less than the volume of hydrogen produced.

Figure 11 shows the volumes of hydrogen collected in the 50 cm³ measuring cylinder after 40 seconds and after 100 seconds.

Determine the number of moles of hydrogen collected between 40 seconds and 100 seconds.

The volume of one mole of any gas at room temperature and pressure is 24 dm³.

A different student investigated how the concentration of sulfuric acid affected the rate of the reaction.

The student did a different experiment using sulfuric acid of

The student calculated the number of moles of hydrogen collected after every 20 seconds.

Figure 12 shows the results.

Determine the rate of reaction at 45 seconds.

You should draw a tangent on Figure 12.

Give your answer in standard form.

Figure 13 shows the results for 0.40 mol/dm³ sulfuric acid.

The student repeated the experiment using 0.20 mol/dm³ sulfuric acid instead of 0.40 mol/dm³ sulfuric acid.

Excess zinc was used in each experiment.

Sketch a line on Figure 13 to show the results you would expect.

Explain how increasing the temperature would affect the rate of reaction between zinc and sulfuric acid.

This question is about oxygen.

Scientists think that there was little or no oxygen in the Earth’s early atmosphere.

Which planet today has an atmosphere that is similar to the Earth’s early atmosphere?

Tick (✓) one box.

Which is the approximate percentage of oxygen in the Earth’s atmosphere today?

Tick (✓) one box.

Which two of the following increased the percentage of oxygen in the Earth’s atmosphere?

Tick (✓) two boxes.

Some scientists think that 1100 million years ago the Earth’s atmosphere contained:

• 16% oxygen

• 4% carbon dioxide.

Complete Figure 1.

You should:

• complete the y-axis scale

• plot the percentage of oxygen in the Earth’s atmosphere 1100 million years ago.

Oxygen is produced when manganese dioxide is added to hydrogen peroxide solution.

The equation for the reaction is:

hydrogen peroxide → water + oxygen

A student investigated the effect of changing the temperature on the decomposition of hydrogen peroxide.

This is the method used.

1. Add 5 cm³ of hydrogen peroxide solution to three test tubes labelled A, B and C.

2. Place each test tube in a water bath at a different temperature.

3. Add 0.2 g of manganese dioxide to each test tube.

Figure 2 shows the results.

Which test tube contained hydrogen peroxide solution at the highest temperature?

Tick (✓) one box.

The student tested the gas produced.

What is used to prove that the gas is oxygen?

Tick (✓) one box.

Manganese dioxide does not appear in the chemical equation for this reaction.

Which is a correct statement about manganese dioxide in this reaction?

Tick (✓) one box.

A student investigated the rate of the reaction between zinc and sulfuric acid.

Hydrogen gas is produced during this reaction.

Figure 7 shows the apparatus.

This is the method used.

1. Add 50 cm³ of sulfuric acid to a conical flask.

2. Add 2.0 g of zinc to the conical flask.

3. Quickly put a stopper in the conical flask and start a timer.

4. Measure the time taken to collect 20 cm³ of gas.

5. Repeat steps 1 to 4 three more times.

Suggest why the stopper must be put in the conical flask as quickly as possible in step 3.

The student calculated the rate of the reaction for each trial.

Table 7 shows the results of the calculations.

Determine the mean time taken to collect 20 cm³ of gas.

Do not include any anomalous results.

Use the equation:

The student changed the investigation so that the mean time taken to collect 20 cm³ of gas was greater.

Which two changes would increase the mean time taken to collect 20 cm³ of gas?

Tick (✓) two boxes.

Hydrogen gas is produced during this reaction.

Describe the test for hydrogen gas.

Give the result of the test.

This question is about alcohols and carboxylic acids.

Alcohols are used as fuels.

A student burned 1.00 g of six alcohols and determined the energy released from each.

Table 8 shows the results.

Calculate the mass of ethanol that must be burned to release the same amount of energy as burning 1.00 g of heptanol.

The energy released in kJ/g varies with the number of carbon atoms in one molecule of each alcohol.

Plot the data from Table 8 on Figure 8.

Estimate the energy released in kJ when 1.00 g of octanol (C₈H₁₇OH) is burned.

Use Figure 8.

Carbon dioxide is produced when alcohols are burned.

Carbon dioxide is identified by bubbling the gas through limewater.

Complete the sentence.

Choose the answer from the box.

Limewater is an aqueous solution of

Give the result of the test when carbon dioxide is bubbled through limewater.

Ethanoic acid can be produced from ethanol.

What is reacted with ethanol to produce ethanoic acid?

Tick (✓) one box.

Ethanoic acid contains the functional group –COOH

Complete the displayed structural formula of this functional group.

Ethanoic acid reacts with different compounds.

Draw one line from each compound to a product of the reaction of the compound with ethanoic acid.

Product of the reaction

A student investigated the rate of the reaction between zinc and sulfuric acid. Hydrogen gas is produced during this reaction. Figure 1 shows the apparatus.

This is the method used.

1. Add 50 cm³ of sulfuric acid to a conical flask.

2. Add 2.0 g of zinc to the conical flask.

3. Quickly put a stopper in the conical flask and start a timer.

4. Measure the time taken to collect 20 cm³ of gas.

5. Repeat steps 1 to 4 three more times.

Suggest why the stopper must be put in the conical flask as quickly as possible in step 3.

The student calculated the rate of the reaction for each trial. Table 1 shows the results of the calculations.

Determine the mean time taken to collect 20 cm³ of gas. Do not include any anomalous results. Use the equation:

The student changed the investigation so that the mean time taken to collect 20 cm³ of gas was greater. Which two changes would increase the mean time taken to collect 20 cm³ of gas? Tick (✓) two boxes.

Hydrogen gas is produced during this reaction. Describe the test for hydrogen gas. Give the result of the test.

This question is about alcohols and carboxylic acids.

Alcohols are used as fuels. A student burned 1.00 g of six alcohols and determined the energy released from each. Table 2 shows the results.

Calculate the mass of ethanol that must be burned to release the same amount of energy as burning 1.00 g of heptanol.

The energy released in kJ/g varies with the number of carbon atoms in one molecule of each alcohol. Plot the data from Table 2 on Figure 2.

Estimate the energy released in kJ when 1.00 g of octanol (C₈H₁₇OH) is burned. Use Figure 2.

Carbon dioxide is produced when alcohols are burned. Carbon dioxide is identified by bubbling the gas through limewater.

Complete the sentence. Choose the answer from the box.

Limewater is an aqueous solution of.

Give the result of the test when carbon dioxide is bubbled through limewater.

Ethanoic acid can be produced from ethanol.

What is reacted with ethanol to produce ethanoic acid? Tick (✓) one box.

Ethanoic acid contains the functional group –COOH Complete the displayed structural formula of this functional group.

Ethanoic acid reacts with different compounds. Draw one line from each compound to a product of the reaction of the compound with ethanoic acid.

Product of the reaction

This question is about water.

Sewage is waste water. Sewage contains organic matter.

Describe how sewage is treated to remove organic matter.

Sea water and ground water are treated to make them potable. Table 5 shows information about the composition and treatment of sea water and of ground water.

Sea water is desalinated during Process 1. Which pair of concentrations could represent X in Table 5 ? Tick (✓) one box.

Explain why the concentrations of sodium ions and of chloride ions in the ground water in Table 5 are unchanged by Process 1.

Explain why the ground water in Table 5 requires Process 2 before the water is safe to drink.

After treatment the ground water in Table 5 is sold by a company as pure water. The ground water in Table 5 is not chemically pure because the water contains sodium ions and chloride ions.

Suggest what the company means by ‘pure’.

Chlorine is also used to treat some ground water. Describe the test for chlorine gas. Give the result of the test.

This question is about substances used to make windows and window frames.

Figure 2 shows a window.

Glass is made by heating sand with two other materials.

Which two other materials are used to make glass?

Tick (✓) two boxes.

Window frames need to be:

• easy to install

• resistant to damage.

The polymers poly(chloroethene) and HDPE are used to make window frames.

Table 3 shows information about poly(chloroethene) and HDPE.

Suggest one advantage of using poly(chloroethene) compared with HDPE to make window frames.

Give one reason for your answer.

Use Table 3.

Suggest one advantage of using HDPE compared with poly(chloroethene) to make window frames.

Give one reason for your answer.

Use Table 3.

Figure 3 shows the displayed structural formula of poly(chloroethene).

Which monomer is used to make poly(chloroethene)?

Tick (✓) one box.

Chlorine gas is used to produce poly(chloroethene).

Describe a test to identify chlorine gas.

Give the result of the test.

Wood can be used instead of polymers to make window frames.

• Polymers are unreactive.

• Polymers are produced from crude oil.

• Wood breaks down in wet conditions.

• Wood is produced from trees.

Suggest one advantage of using polymers and one advantage of using wood to make window frames.

Advantage of polymers

Advantage of wood

Window frames can also be made from an alloy of aluminium.

6.00 kg of the alloy is used to make a window frame.

Table 4 shows the mass of each element in 6.00 kg of the alloy.

Calculate the percentage of aluminium in 6.00 kg of the alloy.

Why is an alloy used instead of pure aluminium to make window frames?

A student investigated the rate of the reaction between zinc and sulfuric acid.

This is the method used.

1. Pour 40 cm³ of sulfuric acid into a conical flask.

2. Add 2.0 g of zinc powder to the conical flask.

3. Put the stopper in the conical flask.

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

Figure 4 shows part of the apparatus used.

Figure 4

X shows where a piece of equipment is connected to measure the volume of hydrogen gas collected.

Complete Figure 4 to show the equipment used.

The student made an error setting up the delivery tube shown in Figure 4.

Describe the error and the problem this error would cause.

The student then set up the apparatus correctly.

Figure 5 shows the student’s results.

Complete Figure 5 by drawing a line of best fit.

Determine the mean rate of reaction between 0 seconds and 60 seconds.

Use the equation:

Use data from Figure 5.

Give the unit.

Choose the answer from the box.

The student repeated the investigation using sulfuric acid of a higher concentration.

The student plotted the results and drew a line of best fit.

How would the line of best fit for higher concentration compare with the line of best fit for lower concentration?

Tick (✓) one box.

This question is about the rate of the reaction between hydrochloric acid and calcium carbonate.

A student investigated the effect of changing the size of calcium carbonate lumps on the rate of this reaction.

This is the method used.

1. Pour hydrochloric acid into a conical flask up to the 50 cm³ line.

2. Add 10.0 g of small calcium carbonate lumps to the conical flask.

3. Attach a gas syringe to the conical flask.

4. Measure the volume of gas produced every 20 seconds for 100 seconds.

5. Repeat steps 1 to 4 using 10.0 g of large calcium carbonate lumps.

The student used the 50 cm³ line on the conical flask to measure the volume of hydrochloric acid.

Suggest a piece of equipment the student could use to make the measurement of volume more accurate.

Carbon dioxide gas is produced in the reaction between hydrochloric acid and calcium carbonate.

Which test is used to identify carbon dioxide gas?

Tick (✓) one box.

Table 2 shows the student’s results for large calcium carbonate lumps.

Figure 4 shows the student’s results for small calcium carbonate lumps.

Complete Figure 4.

You should:

• plot the data for large calcium carbonate lumps from Table 2 on Figure 4

• draw a line of best fit for large calcium carbonate lumps.

Determine the mean rate of reaction using small calcium carbonate lumps between 0 seconds and 60 seconds.

Use the equation:

Use Figure 4.

Describe what happens to the volume of gas collected using small calcium carbonate lumps:

• between 0 and 20 seconds

• between 80 and 100 seconds.

Use Figure 4.

Between 0 and 20 seconds

Between 80 and 100 seconds

The balance used to weigh 10.0 g of calcium carbonate lumps caused an error.

The balance always read 0.2 g before being used.

What type of error was caused by the balance?

Tick (✓) one box.

Figure 5 shows the dimensions of two cubes of calcium carbonate.

A cube of calcium carbonate has six faces.

Calculate the total surface area of the large cube of calcium carbonate.

Use Figure 5.

The large cube of calcium carbonate was divided into eight smaller cubes.

The eight smaller cubes have a greater total surface area than the one large cube.

Compare the rate of reaction when using the eight smaller cubes with the rate of reaction when using the large cube.

Complete the sentence.

Choose the answer from the box.

This question is about algae. A student:

• placed algae in water containing dissolved carbon dioxide

• shone bright light on the algae.

Gas bubbles were collected as the algae photosynthesised.

Describe a test that would identify the gas collected. Give the result of the test.

Glucose is produced when algae photosynthesise. Name two naturally occurring polymers produced from glucose.

Figure 6 shows the displayed structural formula of an amino acid called glycine.

Figure 6

How many functional groups are there in the molecule in Figure 6 ? Tick (✓) one box.

Glycine reacts by condensation polymerisation to produce a polypeptide and one other substance. Name the other substance produced.

Scientists think that algae may have used gases in Earth’s early atmosphere. Algae need an element to produce the molecule in Figure 6 which is not present in water or carbon dioxide. Which two gases from Earth’s early atmosphere could have provided this element?

The development and function of algae are controlled by a naturally occurring polymer. Figure 7 represents the shape and structure of this polymer.

Describe the shape and structure of this polymer.

Some students investigated the rate of decomposition of hydrogen peroxide.

The equation for the reaction is:

hydrogen peroxide → water + oxygen

Complete the sentence.

Choose an answer from the box.

The students tested the gas produced to show that it was oxygen.

The students used.

Student A investigated the effect of the particle size of a manganese dioxide catalyst on the rate of the reaction.

This is the method used.

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

2. Add some fine manganese dioxide powder to the conical flask.

3. Measure the volume of oxygen produced every 30 seconds for 10 minutes.

4. Repeat steps 1 to 3 two more times.

5. Repeat steps 1 to 4 with coarse manganese dioxide lumps.

The method student A used did not give repeatable results.

How could student A make the results repeatable?

Tick (✓) one box.

Student B used a method which gave repeatable results.

How could student B improve the accuracy of these results?

Tick (✓) one box.

Figure 5 shows student B ’s results for coarse manganese dioxide lumps.

Calculate the mean rate of reaction between 30 and 250 seconds for coarse manganese dioxide lumps.

Use Figure 5 and the equation:

Give your answer to 3 significant figures.

Volume of oxygen formed

Mean rate of reaction = cm³/s

Fine manganese dioxide powder produces a higher rate of reaction than coarse manganese dioxide lumps.

Sketch on Figure 5 the results you would expect for student B ’s experiment with fine manganese dioxide powder.

Hydrogen peroxide molecules collide with manganese dioxide particles during the reaction.

Why does fine manganese dioxide powder produce a higher rate of reaction than coarse manganese dioxide lumps?

Tick (✓) one box.

Some students investigated the rate of decomposition of hydrogen peroxide, H₂O₂

The equation for the reaction is:

The catalyst for the reaction is manganese dioxide.

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

Give the result of the test.

Student A investigated the effect of the particle size of manganese dioxide on the rate of the reaction.

This is the method used.

1. Measure 25 cm³ of 0.3 mol/dm³ hydrogen peroxide solution into a conical flask.

2. Add a spatula of fine manganese dioxide powder to the conical flask.

3. Measure the volume of gas produced every minute for 10 minutes.

4. Repeat steps 1 to 3 with some coarse manganese dioxide lumps.

The method student A used did not give valid results.

What two improvements could student A make to the method to give valid results?

Tick (✓) two boxes.

Student B used a method which gave valid results.

Figure 9 shows student B ’s results.

Determine the mean rate of reaction in cm³/s between 2 and 4 minutes for coarse manganese dioxide lumps.

Give your answer to 2 significant figures.

Use data from Figure 9.

Hydrogen peroxide molecules must collide with manganese dioxide particles for catalysis to take place.

Student B repeated the experiment with coarse lumps of manganese dioxide.

Student B used the same volume of 0.2 mol/dm³ hydrogen peroxide instead of 0.3 mol/dm³ hydrogen peroxide.

Sketch on Figure 9 the curve you would expect to see.

Assume that the reaction is complete after 9 minutes.

The rate of reaction is different when manganese dioxide is used as a fine powder rather than coarse lumps.

Explain why.

You should answer in terms of collision theory.