OCR GCSE Chemistry A (Gateway) Paper 4 Higher June 2018 question paper J248/04

Which statement is true for a reversible reaction when it is at dynamic equilibrium?

A The concentration of the products is increasing.

B The rate of the backward reaction is greater than the rate of the forward reaction.

C The rate of the forward reaction is equal to the rate of the backward reaction.

D The rate of the forward reaction is greater than the rate of the backward reaction.

What is the formula of the product in this equation?

A C₂H₃Br

B C₃H₅Br₂

C C₂H₃Br

D C₃H₆Br₂

The following statements describe one possible theory for how the Earth’s atmosphere evolved.

The statements are not in the correct order.

What is the correct order for the sentences?

A 3, 5, 4, 6, 1, 2

B 3, 6, 5, 4, 1, 2

C 6, 1, 3, 5, 4, 2

D 6, 3, 1, 5, 4, 2

Look at the information about four different polymers.

Which polymer would be best for making a plastic washing up bowl?

Look at the equation for a reversible reaction.

The reversible reaction forms a dynamic equilibrium in a sealed container.

Which of the following would move the position of equilibrium to the right ?

A Decreasing the pressure and decreasing the temperature.

B Increasing the pressure and decreasing the temperature.

C Increasing the pressure and increasing the temperature.

D Increasing the pressure and using a catalyst.

How much 0.2 mol / dm³ hydrochloric acid solution could you make from 100 cm³ of 1.0 mol / dm³ 11 hydrochloric acid?

20 cm³ A

200 cm³ B

500 cm³ C

600 cm³ D

Which one of the following is an advantage of phytoextraction?

A A high concentration of a metal can be obtained from a low grade ore.

B Bacteria are used to dissolve metals instead of chemical solutions.

C Better crops of plants are harvested.

D Phytoextraction is a quick process and is not affected by poor weather.

Group 1 elements get more reactive down the group.

Which statement explains why?

A The outer electron is closer to the nucleus and lost more easily.

B The outer electron is further from the nucleus and lost more easily.

C There is less shielding from the inner electrons.

D There is more attraction between the nucleus and the outer electron down the group.

A student wants to test the purity of a liquid by testing its boiling point.

The actual boiling point of the pure liquid is 85 °C.

Which equation represents the percentage (%) difference between the student’s value and the actual value?

This question is about life‑cycle assessment.

A car company is developing three new cars:

• A petrol car

• A diesel car

• An electric car.

They do a life‑cycle assessment of each car.

Look at the information about the life‑cycle assessment of each car.

The company decides to manufacture and sell the electric car.

Explain why they make this choice.

Use the information from the life‑cycle assessment to help you.

The fuels for the petrol and diesel cars are made from crude oil.

Crude oil is separated into different parts by fractional distillation.

The diagram shows a fractionating column.

Explain why crude oil vapour can be separated by fractional distillation.

The table shows the boiling points of molecules present in different crude oil fractions.

Which molecule, A, B, C or D is in the LPG fraction ?

Explain your decision.

Car manufacturers are developing cars that are powered by hydrogen/oxygen fuel cells.

The table shows some information about a 200 km journey using an electric car and a car using a fuel cell.

Evaluate the advantages and disadvantages of using a car powered by a fuel cell, rather than an electric car for the 200 km journey.

A student is using the internet to find out about alcohols. The student finds the following information.

Plot a graph of the boiling points of the alcohols on the grid. Draw a line of best fit.

The student could not find a value for the boiling point of butanol, C₄H₉OH.

Use the graph to estimate the boiling point of butanol.

Draw the displayed formula of butanol, C₄H₉OH.

The alcohols all react in a similar way because they all contain the same functional group

What is the functional group in an alcohol molecule?

Ethanol, C₂H₅OH, can be oxidised to ethanoic acid using potassium manganate(VII).

What is the formula of ethanoic acid?

A student investigates the reaction between marble chips, CaCO₃, and hydrochloric acid.

Calcium chloride, CaCl₂, carbon dioxide and water are made.

Write a balanced symbol equation for the reaction.

The student does three experiments, A, B and C.

In each experiment she uses a different size of marble chip. She uses the same mass of marble in each experiment. She also uses the same concentration of acid.

Look at the graph of her results.

Look at the line for experiment B on the graph.

When is the rate of reaction greatest ?

Choose your answer from the list.

0 – 30 seconds

30 – 60 seconds

60 – 90 seconds

90 – 120 seconds

Answer =........ seconds

Look at the line for experiment C.

Calculate the rate of reaction during the first 45 seconds.

Give your answer to 2 significant figures.

Answer =........ cm³ / s

The rate of reaction between marble and hydrochloric acid can be decreased by:

• Using a more dilute solution of hydrochloric acid

• Cooling the acid.

Explain how each of these methods make the reaction slower.

Use ideas about collisions between particles.

A catalyst can be used to increase the rate of a reaction.

Look at the energy profile diagram for a reaction without a catalyst.

Complete the energy profile diagram to show

The reaction profile for the reaction with a catalyst.

Label the activation energy for the reaction with a catalyst.

19* Ethanol is manufactured by reacting ethene, C₂H₄, with steam.

The reaction is reversible and occurs in a closed system.

Only 5% of the ethene is converted into ethanol at each pass through the reactor.

By removing the ethanol from the equilibrium mixture and recycling the ethene, it is possible to achieve an overall 95% conversion.

Explain why the conditions used for the process are chosen.

Describe and explain how the student could improve his experiment to get a more accurate value.

Student B does a titration.

Sodium hydroxide solution is slowly added to the beaker of dilute sulfuric acid.

The pH probe is connected to a datalogger.

Suggest how student B ’s method is better than student A ’s.

Look at the display from the datalogger.

Volume of alkali added (cm³)

What is the pH value when 15 cm³ of alkali has been added? (i)

What volume of alkali is needed to exactly neutralise the sulfuric acid?

Student B does another experiment.

This time she uses:

• 20.0 cm³ of dilute hydrochloric acid in the beaker

• sodium hydroxide solution of concentration 0.200 mol / dm³ in the burette.

Look at student B’s results.

Student B decides to only use the results from titration numbers 2 and 4.

Explain why.

Look at the equation for the reaction between hydrochloric acid, HC l, and sodium hydroxide, NaOH.

HCl + NaOH → NaCl + H₂O

Calculate the concentration of hydrochloric acid in mol / dm³.

Use the average titre, in cm³, from titration numbers 2 and 4.

Give your answer to 2 significant figures.

Answer =........ mol / dm³

A student dissolves 0.6 g of zinc sulfate in 250 cm³ of water. 21 (a)

Calculate the volume of the water in dm³. (i)

Use your answer to part (a)(i) to help you calculate the concentration of the zinc sulfate in g / dm³.

Answer =........ g / dm³

Zinc reacts with sulfuric acid. Zinc sulfate and hydrogen gas, H₂, are made.

Zn + H₂SO₄ → ZnSO₄ + H₂

Calculate the amount of hydrogen gas, in mol, that could be made from 3.27 g of zinc

Use your answer to part (b)(i) to calculate the volume of hydrogen gas produced at room temperature and pressure.

One mole of any gas occupies 24 dm³ at room temperature and pressure.

Hydrogen can be made by reacting methane with steam.

CH₄ + H₂O → CO + 3H₂

The atom economy for this process is 17.6%.

Hydrogen can also be produced by the decomposition of ammonia.

This reaction requires a catalyst.

2NH₃ → N₂ + 3H₂

Calculate the atom economy for the production of hydrogen from ammonia.

Give your answer to 3 significant figures.

Suggest other factors, apart from atom economy, that must be considered when deciding which reaction pathway to choose for the manufacture of hydrogen.

What feature of butene molecules allows them to act as monomers?

Butene is an alkene.

What is the general formula for an alkene?

Butene undergoes addition polymerisation to form poly(butene).

Write the displayed formulae, for poly(butene).

DNA molecules are polymers made from four different monomers.

What are the monomers in DNA called?

Polyesters are polymers made by condensation polymerisation.

What is the minimum number of functional groups that a monomer must have to form a condensation polymer?

What is the formula of the molecule that is eliminated in the reaction to form a polyester?

Nylon is another polymer formed in a condensation polymerisation reaction.

Nylon can be made from hexanedioyl dichloride and hexane‑1,6‑diamine.

Both chemicals are highly corrosive.

A solvent is needed which is highly flammable.

Describe how to make nylon in a laboratory.

Describe and explain three precautions needed to control the hazards in this experiment.