Organic Chemistry (OCR Gateway GCSE Chemistry)

Heptane is an alkane with seven carbons.

What is the chemical formula of heptane?

The complete combustion of pentane, C₅H₁₂, takes place in the following unbalanced equation:

_C₅H₁₂   +   _O₂ →   _CO₂   +  _H₂O

What numbers will balance the reaction?

Which of the following molecules is an alkene?

The following molecule can undergo addition polymerisation. 

What it the correct repeat unit?.

Polyesters can be made by condensation polymerisation. Ethanediol can react with butanedioic acid (a carboxylic acid containing two -COOH groups) to make a polymer.

Which of the following is a correct repeat unit for this polymer?

Which of the following is not true about DNA?

The structure of a polymer is shown below.

What is the correct monomer?

Hydrogen fuel cells can be used to power trains.

Why could people refer to the hydrogen fuel cell trains as the 'new' steam trains?

Hydrogen fuel cells are often used instead of rechargeable batteries in spacecraft.

Which of the following is not an advantage of using hydrogen fuel cells in spacecraft?

Which molecule can be cracked to produce hexane, C₆H₁₄?

Which of the following shows the product of the reaction between propene and bromine?

Crude oil is a mixture of hydrocarbons.

Crude oil is separated into useful fractions.

Which of these mixtures of substances could be in a fraction from crude oil?

What happens to the potential difference of a chemical cell once the reactants are used up?

Crude oil is separated into useful fractions by fractional distillation.

The diagram shows the useful fractions made in fractional distillation.

Which of these fractions has the weakest intermolecular forces?

Crude oil is separated into fractions by fractional distillation.

Look at the diagram of the fractions made in fractional distillation.

Which of these fractions has the lowest boiling point?

What type of reaction takes place between an alkene and hydrogen?

DNA molecules are polymers.

What is the name of the monomers that make up DNA molecules?

Which of the following are the first four members of the homologous series of alcohols?

Look at the displayed formula of the monomer butene.

What is the formula of the polymer formed from butene?

DNA molecules are polymers.

What are the monomers that make up DNA called?

Ethene, C₂H₄, reacts with bromine, Br₂, in an addition reaction.

Which is the balanced symbol equation for this reaction?

The bar chart shows the amount of some fractions made from 100 tonnes of crude oil by fractional distillation.

It also shows the amount of each fraction needed for everyday uses.

Cracking converts large molecules into smaller more useful molecules to make the supply match the demand.

Which fractions are most likely to be cracked to make the supply match the demand?

What is the formula of the product in this equation?

Which displayed formula includes the functional group of an alcohol?

What is the general formula of the fractions produced by the fractional distillation of crude oil?

Which displayed formula shows butanol?

Higher Only

Look at the equations for the reactions that happen at each side of a hydrogen‑oxygen fuel cell.

Reaction 1: 2H₂ (g) → 4H⁺ (aq) + 4e^–
Reaction 2: 4H⁺ (aq) + O₂ (g) + 4e^– → 2H₂O (g)

Which row of the table, A, B, C or D, is correct about reactions 1 and 2?

A hydrogen-oxygen fuel cell produces electricity.

Hydrogen reacts with oxygen to produce water.

What is the equation for the reaction that happens at the anode?

Higher Only

Which pairs of molecules would react to form a polyester?

A student reacts a hydrocarbon with bromine water.

The formula of the product is C₃H₆Br₂.

Which is the displayed formula of the hydrocarbon?

A student bubbles ethene gas into bromine water.

Which displayed formula shows the product of this reaction?

Which of these homologous series can react together to form addition polymers?

A student heats compound X with acidified potassium manganate(VII) solution.

The product of the reaction is compound Y.

What is the colour change seen during this reaction?

What is the formula of the functional group in alcohols?

Higher Only

A condensation polymer is made from two monomers.

• One monomer has two –OH groups in its molecule.
• The other monomer has two –COOH groups in its molecule.

Which term describes the polymer?

Crude oil is separated into fractions by fractional distillation.

Look at the diagram of the fractions made in fractional distillation

Which of these fractions has the strongest intermolecular forces?

Look at the structure of glycine.

Glycine is a monomer that reacts to form proteins.

Glycine contains two different functional groups that allow it to undergo polymerisation.

What are the two functional groups?

Higher Only

Which statement explains why polyamides are condensation polymers?