OCR GCSE Chemistry B (21st Century) Paper 2 June 2022 question paper

Which of the following statements are true only for the solid, which are true only for the liquid and which are true for both?

Tick (✓) one box in each row.

Sodium chloride and magnesium chloride are ionic compounds.

The melting points of sodium chloride and magnesium chloride are shown in the table.

What is the state of sodium chloride and of magnesium chloride at 750 °C?

At 750 °C, sodium chloride is a solid / liquid / gas.

At 750 °C, magnesium chloride is a solid / liquid / gas.

A limitation of the model shown in Fig. 1.1 is that it does not show the reasons why different compounds have different melting points.

Which two statements describe the reasons why compounds have different melting points?

Tick (✓) two boxes.

Ions in different compounds have different chemical symbols.

Ions in different compounds have different charges.

Ions in different compounds have different colours.

The force of attraction between ions is different in different compounds.

Sodium chloride contains sodium ions, Na +, with a single positive charge. (c)

Fig. 1.2 shows the arrangement of electrons in a sodium atom.

Electron arrangement: 2,8,1

Fig. 1.2

Which information from the Periodic Table shows us that a sodium atom contains a total of 11 electrons?

Tick (✓) one box.

the atomic number

the chemical symbol for the element

the group number

the relative atomic mass

Use ideas about electrons to explain why sodium atoms form an ion with a +1 charge.

Jane does an experiment.

She puts 10 cm³ of copper sulfate solution in a boiling tube.

She adds 5 cm³ of sodium hydroxide solution. A precipitate of copper hydroxide forms.

What are the correct state symbols for copper sulfate and copper hydroxide in this experiment?

Tick (✓) one box in each row.

At the end of the reaction, the boiling tube contains a mixture of a precipitate of copper hydroxide in a solution.

Describe how Jane can separate pure, dry copper hydroxide from this mixture.

Jane does more experiments. She adds a different volume of sodium hydroxide solution to 20 cm³ of copper sulfate solution each time. She records the mass of dry copper hydroxide that forms in each experiment.

Table 2.1 shows her results.

Describe the pattern shown by the results in Table 2.1.

Jane wants to change her experiment to make more than 1.00 g of dry copper hydroxide.

Jane and Alex talk about the results.

Jane says, ‘To make more copper hydroxide we need to add more than 35 cm³ of sodium hydroxide solution.’

Alex says, ‘To make more copper hydroxide we need to add more than 20 cm³ of copper sulfate solution.’

Who is right?

Jane

Alex

Use information from Table 2.1 to explain your choice.

Jane plots her results on a graph.

Volume of sodium hydroxide solution added (cm³)

Jane thinks that one of her results is an outlier.

Draw lines of best fit on the graph.

Suggest what the correct mass reading for the outlier should be.

What is the most likely reason for the outlier?

Tick (✓) one box.

Jane did not add enough sodium hydroxide solution.

Some of the copper hydroxide was lost before weighing.

The copper hydroxide contained water when Jane weighed it.

The reaction had not finished.

Before she sets up the cell, Beth tests each gas to check its identity.

Draw lines to connect each gas to its correct test and result.

The fuel cell is filled with potassium hydroxide solution rather than pure water.

This is because potassium hydroxide solution is a better electrical conductor than pure water.

Which statement explains why potassium hydroxide solution is a better electrical conductor than pure water?

Tick (✓) one box.

Potassium hydroxide is acidic.

Potassium hydroxide is a metal.

Potassium hydroxide is very soluble in water.

Potassium hydroxide solution contains charged ions.

This equation shows the reaction that happens in the fuel cell:

Beth does some experiments using different amounts of hydrogen in a fuel cell.

She records the masses of hydrogen and oxygen which are used and the mass of water made each time.

Her results are shown in Table 3.1.

Complete Table 3.1 by predicting the missing amounts for experiments 3 and 4.

In each experiment, Beth notices that the potential difference of the cell decreases after a time.

Why does this happen?

Tick (✓) one box.

The concentration of potassium hydroxide solution increases.

The hydrogen and oxygen are used up.

The reaction takes in energy.

Waste products are made.

Beth’s company wants to use hydrogen fuel cells to provide power for a car.

Most cars use petrol as a fuel.

Beth looks at the information about hydrogen and petrol in Table 3.2.

Use information from Table 3.2 to explain two advantages of using hydrogen, rather than petrol, as a fuel for cars.

Use information from Table 3.2 to explain two reasons why hydrogen is more difficult to use as a fuel for cars than petrol.

The solubility of a salt shows how much salt dissolves in 100 g of water.

The graph shows the solubility of some Group 1 salts in water at different temperatures.

Use the graph to describe how temperature affects the solubility of sodium chloride and potassium chloride.

Use values from the graph to support your answer.

Jack works out a way to predict the solubility of potassium chloride.

He uses this formula:

solubility (g in 100 g of water) = 26 + (0.3 × temperature)

Use Jack’s formula to predict the solubility of potassium chloride at 80 °C.

predicted solubility of potassium chloride at 80 °C =........ g in 100 g water

* Jack decides to check the data given on the graph.

He adds small amounts of solid potassium chloride to water at room temperature (20 °C).

He stirs until the solid dissolves and then adds more.

He stops adding when no more solid dissolves.

The diagrams show some of the apparatus he uses.

Jack wants to find out how much solid potassium chloride dissolves in 100 g of water at different temperatures.

Describe the method Jack should use. Include what he needs to measure, what he needs to control, what he needs to change and what results he should expect.

Some metals are extracted from their ores by heating with carbon.

Other metals are extracted from their ores by electrolysis.

Fig. 5.1 shows the order of reactivity of some metals, compared to carbon.

Which statement explains why calcium must be extracted from its ore by electrolysis?

Tick (✓) one box.

Calcium does not conduct electricity.

Calcium is a non-metal.

Calcium is more reactive than carbon.

Calcium is too unreactive to be extracted using carbon.

Which metal, not listed in Fig. 5.1, is less reactive than carbon?

lithium magnesium potassium silver

Mia makes this statement:

‘The information in Fig. 5.1 shows that all metals which are more reactive than carbon are in Group 1.’

Use information from Fig. 5.1 to help explain why Mia’s statement is only partly correct.

How are iron and aluminium extracted from their ores?

Tick (✓) one box in each row.

After extraction, iron is mixed with other elements to make steel.

Complete the sentences about steel.

Use words from the list.

carbon chlorine sulfur harder softer weaker

To make steel, iron is mixed with small amounts of........

This makes the steel........

Copper is extracted from copper oxide by heating it with carbon.

This is the equation for the reaction that happens:

Write the word equation for the reaction between copper oxide and carbon.

What is oxidised and what is reduced during the reaction between copper oxide and carbon?

Explain your reasons.

oxidised........

reduced........

What would you expect to happen to the total mass of solids during the reaction between copper oxide and carbon?

Tick (✓) one box.

mass of solids becomes zero

mass of solids decreases

mass of solids increases

mass of solids stays the same

Explain how you decided your answer to (d)(iii).

The diagram shows the structures of diamond and carbon dioxide.

The atoms in diamond are held together by single covalent bonds.

How is a single covalent bond formed?

Use ideas about electrons in your answer.

Which of these statements are only true for diamond, which are only true for carbon dioxide and which are true for both?

Tick (✓) one box in each row.

* The melting point is the temperature at which a solid changes to a liquid.

Table 6.1 shows the structures and melting points of diamond and carbon dioxide.

Explain why diamond and carbon dioxide change from a solid to a liquid at different temperatures.

Use ideas about energy, bonds and forces between molecules in your answer.

Fig. 7.1 shows the change in carbon dioxide concentration in the Earth’s atmosphere over the last 575 million years.

Carbon dioxide concentration was at its highest about 530 million years ago.

What was the value of the concentration of carbon dioxide 530 million years ago?

concentration of carbon dioxide =........ ppm (parts per million)

During what period was the concentration of carbon dioxide similar to its concentration today?

from........ to........ millions of years ago

Fig. 7.1 shows the most recent value for the concentration of carbon dioxide to be 380 parts per million (ppm).

Do a calculation to convert 380 ppm into a percentage.

Use this formula:

Some scientists fear that climate change may cause other long-term environmental problems.

Describe two other long-term environmental problems caused by climate change.

Petrol contains cyclo-octane.

Which symbol should be used to warn people of the main hazard when handling cyclo-octane?

Tick (✓) one box.

Write down two safety precautions people should take when filling their cars with petrol.

Carbon makes a much bigger range of different types of molecules than any other element.

Give one reason why carbon atoms can form so many different types of molecules.

Use Fig. 8.1 to help you to answer.

Explain why polyethene and synthetic rubber have different properties.

Use ideas about structure from Fig. 8.1 to help you to answer.

How are nanoparticles different to the other substances in Fig. 8.1 ?

Explain why the structure of carbon nanoparticles helps them to carry medicine molecules into the body.

Ammonia is used to make fertilisers. It is produced in a large-scale process.

The equation shows the reaction that happens in the process:

The process happens in a reactor.

The percentage yield of ammonia is usually between 10% and 20%.

Use the equation to explain why it is not possible to get 100% yield of ammonia.

The gas that leaves the reactor contains ammonia mixed with two other gases.

Use the equation to help you to give the names of the other two gases.

An ammonia factory tests a new reactor.

The table shows the theoretical yield and actual yield for a process in the new reactor.

Calculate the percentage yield for the process in the new reactor.

Ammonia is very soluble in water.

Kofi does an experiment to make some ammonia.

He tries to collect it using the apparatus shown.

Bubbles of ammonia gas enter the water but no gas collects in the test-tube.

What happens to the ammonia gas when it enters the water?

Which apparatus should Kofi use to collect ammonia?

Tick (✓) one box.

burette

gas syringe

measuring cylinder

volumetric flask

Ammonia is an alkaline gas.

The pH of ammonia solution can be measured using a pH meter.

Predict the pH of ammonia.

Describe another method you could use to measure the pH of ammonia solution.