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

Cold packs are used to treat some sports injuries.

They contain ammonium nitrate and water.

The formula of ammonium nitrate is NH₄NO₃.

Name the three elements present in ammonium nitrate.

What is the total number of atoms shown in the formula?

When the ammonium nitrate and water mix in the cold pack, the temperature of the mix decreases.

The diagram shows the reaction profile for this reaction.

What is the name given to a change which makes the temperature of the mix decrease?

Combustion Endothermic Exothermic Freezing

Draw lines to connect each label with its correct position on the diagram.

Kofi plans an experiment to find the energy change when the ammonium nitrate from a cold pack dissolves in water.

The energy change depends on the mass of water and the temperature change.

What apparatus will he need to take the measurements?

Tick (✓) two boxes.

Here are Kofi’s results.

Mass of water used = 250 g

Temperature of water before adding ammonium nitrate = 20.2 °C

Temperature of water after adding ammonium nitrate = 4.8 °C

Calculate the energy change when the ammonium nitrate from the cold pack dissolves in water.

Use the formula: Energy change (J) = 4.2 mass of water (g) temperature change (°C)

Give your answer to 3 significant figures.

Harmful gases such as NO, CO and SO₂ are emitted from car engines running on fossil fuels.

These gases are produced in the car engine.

Draw lines to connect each gas with its formula and how it is formed.

Gas
Formula
How it is formed

Why do the gases not react with each other until they are in contact with the hot catalyst?

Tick (✓) one box.

Suggest why the catalyst is coated on a ceramic honeycomb.

The equation shows one reaction of the gases in the catalytic converter.

Identify which gas is oxidised.

Explain your answer.

Gas which is oxidised........

Explanation........

Magnesium hydroxide reacts with hydrochloric acid in a neutralisation reaction.

Complete the balanced symbol equation for the reaction between magnesium hydroxide and hydrochloric acid.

Draw lines to connect each compound from the reaction with its correct description

Milk of magnesia is a medicine used to neutralise excess acid in the stomach.

Milk of Magnesia

One 15 cm³ spoonful contains 1200 mg of magnesium hydroxide.

Leo does a titration with hydrochloric acid to check the amount of magnesium hydroxide in one spoonful of Milk of Magnesia.

This is the method:

• Add 15 cm³ of Milk of Magnesia into a conical flask

• Add a few drops of indicator

• Add hydrochloric acid from a measuring cylinder until all of the magnesium hydroxide is neutralised.

When should Leo stop adding the acid?

Tick (✓) one box.

Leo decides to measure the acid with a more accurate piece of apparatus instead of the measuring cylinder.

Which piece of apparatus should he use?

Beaker Burette Flask Thermometer

Leo repeats the titration with the more accurate piece of apparatus.

Here are his results.

Calculate the mean volume of acid used.

The label says that there is 1200 mg of magnesium hydroxide in one 15 cm³ spoonful.

Calculate the volume of hydrochloric acid needed to react with the magnesium hydroxide in the spoonful.

Use the formula:

Mass of magnesium hydroxide(g) = volume of hydrochloric acid(cm³) 0.044

Sodium is a metal and oxygen is a non-metal.

Complete the table to describe the difference in the properties of metals and non-metals.

Use words from the list.

Complete the sentence to explain why sodium is a good conductor of electricity.

Sodium is a good conductor of electricity because it has electrons / ions / molecules which

are fixed / mobile / static.

Sodium has an electronic structure 2.8.1 and oxygen has an electronic structure 2.6.

Complete the table to show the position of these two elements in the Periodic Table.

Use the Data Sheet.

Sodium and oxygen react together to form sodium oxide.

Complete the table to show the electronic structures and charges of the ions formed.

Paper chromatography can be used to identify dyes in a mixture.

Rf values are used to identify dyes. They are calculated using this equation:

The Rf value of a dye can be calculated from the result of an experiment and compared with Rf values in a data book.

Table 5.1 shows the results of an experiment to identify an unknown dye.

Table 5.2 shows the Rf values of some dyes in a data book.

Which dye has been identified from the experimental results in Table 5.1 ?

Use a calculation to explain your answer.

The diagrams show the structures of some forms of carbon.

How do the diagrams show that all the structures are the same element?

Tick (✓) one box.

Which statements about these structures are true only for diamond, which are true only for fullerenes, and which are true for all the structures ?

Tick (✓) one box in each row.

Fullerenes are nanoparticles.

What is the approximate size of a nanoparticle?

≤100 nm 1000 nm 10 000 nm ≥10 000 nm

Fullerenes can be used to carry drugs into the body.

Which two statements explain why?

Tick (✓) two boxes.

Some people do not agree with the use of nanoparticles to carry drugs into the human body. Others think that the benefits outweigh the risks.

Suggest one risk and one benefit to a person’s health of using fullerenes to carry drugs into the body.

Risk........

Benefit........

Table 7.1 shows some information about the elements in Group 17(7) of the Periodic Table.

Name the most reactive member of Group 17(7).

Name one member of Group 17(7) that is not shown in Table 7.1.

Predict the state and colour at 20 °C, the reaction with iron wool and the product of the reaction for the element identified in (ii).

State and colour at 20 °C........

Reaction with iron wool........

Product formed with iron wool........

The elements in Group 17(7) form compounds with other metals.

Table 7.2 shows information about some of these compounds.

Complete the table to show the missing ions and formula.

Calculate the relative formula mass for FeF₃.

Use the Data Sheet.

The table gives information about some of the compounds present in crude oil.

Complete the table to show the missing molecular formula and empirical formula.

Predict the boiling point for the compound with 7 carbon atoms.

Predict the state of the 5 carbon compound at room temperature (20 °C).

Explain your answer.

State........

Explanation........

All the compounds in the table are in the same homologous series.

All members of a homologous series have the same general formula.

Give two other characteristics of a homologous series that are shown in the table.

Solid calcium carbonate reacts with dilute hydrochloric acid to form calcium chloride, carbon dioxide and water.

Jane investigates the rate of this reaction. She measures the change in mass during the reaction over five minutes.

She uses 10 g of calcium carbonate lumps and 50 cm³ of dilute hydrochloric acid.

The graph shows Jane’s results.

What was the time taken for the reaction to finish?

What was the total mass lost during the reaction?

Calculate the average rate of the reaction.

Rate of reaction =........ g / s

Jane repeats the experiment with 10 g of calcium carbonate powder instead of 10 g of lumps. She keeps everything else the same.

Sketch a line on the graph to show the results she should expect.

Complete the sentences to explain why the rate of reaction changes when powdered calcium carbonate is used instead of lumps.

The surface area of 10 g of powdered calcium carbonate is larger than / smaller than / the same as 10 g of lumps.

The total volume of 10 g of powdered calcium carbonate is larger than / smaller than / the same as 10 g of lumps.