OCR GCSE Chemistry B (21st Century) Paper 1 June 2019 question paper

Chemists add chlorine to water. This makes the water suitable to drink.

Choose the test for chlorine.

Tick (✓) one box.

Choose words from the list below to complete the sentences.

You may use each word once, more than once, or not at all.

animals diseases microorganisms smelly toxic

Chlorine is used to kill........ in water.

This stops the untreated water from causing........

Chlorine can be hazardous because it is........

A chlorine atom has seven electrons in its outer shell.

Complete the ‘dot and cross’ diagram for an HC l molecule.

You only need to show outer-shell electrons.

2 ‘Camping gas’ contains butane.

Fig. 2.1 shows a model of butane. The model helps us to imagine what butane looks like.

Fig. 2.1 is called a ‘ball and stick’ model.

What do the ‘sticks’ show?

covalent bonds

intermolecular forces

ionic bonds

shared electrons

Which statement is correct about the model of butane shown in Fig. 2.1 ?

Tick (✓) one box.

58 g of butane contain 48 g of carbon.

What is the percentage of carbon in butane?

Give your answer to 2 significant figures.

This question is about the efficiency of LED light-bulbs in 2015 compared to 2011.

The table shows part of a life-cycle assessment for the two light-bulbs. The numbers in the table compare the energy used to give the same amount of light in a certain time.

Which stage uses the most energy?

In total, the 2011 light-bulb uses more energy than the 2015 light-bulb.

Calculate the difference in the total energy used.

The last stage in the life-cycle assessment is missing.

Name the last stage.

The percentage decrease in energy use at ‘manufacture’ stage from 2011 to 2015 is given by:

Calculate the percentage decrease in energy use at ‘use of the light-bulb’ stage from 2011 to 2015.

Give your answer to 2 significant figures.

Some cars use hydrogen fuel cells.

This is the reaction that happens in the fuel cell:

Name the product of this reaction.

Most cars still use petrol as a fuel.

Give two advantages of using hydrogen as a fuel for cars.

The reaction profile below shows the energy changes when hydrogen and oxygen react together.

You may use each letter once, more than once, or not at all.

Which arrow, A, B, or C, shows the activation energy for the reaction?........

Which arrow, A, B, or C, shows that the reaction is exothermic?........

Calculate the relative formula mass of H₂O.

Relative formula mass of H₂O =........

4 g of hydrogen burns giving out 240 kJ of energy.

How much energy is given out when 20 g of hydrogen burns?

A chemist makes a teaspoon out of gallium metal.

Gallium looks like aluminium. Gallium melts at 30 °C and aluminium melts at 660 °C.

Tea is made with boiling water.

What would happen if a gallium spoon is used to stir hot tea?

Explain your answer.

When Mendeleev made his Periodic Table, he left a gap below aluminium.

Later gallium was discovered and put into this gap.

Give one reason why gallium fitted into this gap.

Tick (✓) one box.

When gallium reacts it loses three electrons.

Which ion is formed?

Ga Ga⁺ Ga²⁺ Ga³⁺ Ga⁻ Ga²⁻ Ga³⁻

Ionic compounds have high melting points.

Which two statements explain this?

Tick (✓) two boxes.

Mendeleev put potassium and sodium in the same group because they both react with water.

Ali’s teacher puts a piece of sodium into water. The teacher then puts a piece of potassium into water.

Give two ways Ali could tell potassium is more reactive than sodium.

Mia has three metals, A, B and C, that she reacts with water.

This is what she sees:

Metal A Fizzes and reacts quickly.

Metal B A few bubbles appear after some time.

Metal C Slow fizzing.

Put the metals in order of reactivity, with the most reactive first.

Which metal forms positive ions most easily?

Metal A is placed in copper sulfate solution. A brown metal is made.

Name the brown metal........

The diagram below shows the bonding in metals.

Label the diagram by writing on the dotted lines.

Use words from the list below.

Metals conduct electricity and are malleable (shapeable).

Draw lines to connect each property with its correct explanation.

Dalton was one of the first scientists to model the atom.

Rutherford later developed an improved model of the atom from experiments.

Rutherford’s model describes:

• a small positive nucleus

• the nucleus surrounded by empty space

• negatively charged particles orbiting in this empty space.

Describe how Dalton’s model of the atom was different to Rutherford’s.

Name the ‘negatively charged particles’ in Rutherford’s model.

We currently know that the nucleus of an atom contains protons and neutrons.

Complete the table by filling in the blank spaces.

The table shows the number of protons and neutrons in a sodium atom.

Complete the table by filling in the blank spaces.

Kai finds some information on the internet.

Kai writes some notes: 1 Atoms are smaller than molecules. 2 Atoms are smaller than protons.

Is Kai correct?

Use the information in Table 7.1 to explain your answer.

Layla puts some Tumsoothe in a beaker and places it on a balance.

She adds hydrochloric acid to the contents of the beaker and this reaction happens:

Layla writes down the mass every 10 seconds, as shown in Table 8.1.

Plot a graph of mass against time on the axes below, using Table 8.1.

Add a curve of best fit to the graph.

Estimate the mass of the beaker at 100 seconds. Use the graph to help you.

Draw an F on your graph where the rate of reaction is the fastest.

Describe the rate of change of mass during the reaction.

Explain how you worked this out from the graph.

The law of conservation of mass says:

‘The mass at the start and end of a reaction must be the same.’

Explain why the law is true for the reaction between NaHCO₃ and HCl, even though the reading on the balance changes.

Layla says, ‘This is good quality data.’

Do you agree?

Explain your answer.

Calculate the mean value for the volume of acid added in the titration.

Sundip reacts zinc with dilute sulfuric acid.

Complete the symbol equation for the reaction.

Sundip drops a piece of zinc into some dilute sulfuric acid.

The zinc fizzes.

What is the name of the gas given off?

Sundip then drops some zinc powder into some dilute sulfuric acid.

Explain why the fizzing is faster with zinc powder.

Sundip adds some blue copper sulfate solution and zinc to the acid.

Sundip thinks that the copper sulfate is a catalyst in the reaction.

If Sundip is right, which statements are correct?

Tick (✓) two boxes.

An industrial firm makes nitrogen oxide, NO, by the following reaction:

Which two statements are correct at equilibrium?

Tick (✓) two boxes.

The NO then reacts with air and water to form nitric acid. Nitric acid is an ingredient used to make fertilisers.

Why is nitric acid not used as a fertiliser on its own?

Tick (✓) one box.

In theory, 28 g of nitrogen makes a maximum of 60 g of NO.

However, in a reaction, 28 g of nitrogen makes 9.0 g of NO.

Calculate the percentage yield of the reaction.

Diamond and graphite are two forms of carbon.

Fig. 11.1 shows the structure of diamond:

Explain why diamond has a high melting point.

Fig. 11.2 shows the structure of graphite.

Graphite also has a high melting point.

Describe and explain two other properties of graphite.

Use the structure shown in Fig. 11.2 to help explain your answers.

Diamond has a high density.

1.0 g of diamond has a volume of 0.29 cm³.

Calculate the mass of 1.0 cm³ of diamond.

Give your answer to 2 significant figures.

12 g of diamond produces 44 g of CO₂ when it is burned completely.

Jane makes some statements about graphite and diamond:

1 ‘Complete combustion of 12 g of graphite produces less than 44 g of CO₂.’

2 ‘This is because atoms in graphite are further apart than in diamond.’

Do you agree with Jane’s statements?

Explain your answer.

Ben uses chromatography to investigate a solid black food dye.

Ben tests the solubility of the dye in three solvents.

Here are his results:

Which of the three solvents are non-aqueous?

Ben uses paper chromatography to investigate the dye.

Which of the three solvents should Ben use in his investigation?

Here is some information about the experiment:

chromatogram at the start
chromatogram at the end

Name the stationary phase.

What is wrong with the way Ben set up his experiment?

Explain your answer.

Which spot has the greatest R_f value in the chromatogram at the end?

Explain your answer.

Ben thinks the dye is a pure substance. Kareem, another student, disagrees.

Who do you agree with?

Explain your answer.

Ben measures the melting point of the dye.

Describe what Ben would see if the dye is pure.