Edexcel GCSE Chemistry: Organic Chemistry, Fuels and Earth Science

Poly(ethene) is made by addition polymerisation. A polyester is made by condensation polymerisation from a diol and a dicarboxylic acid.

Compare addition polymerisation and condensation polymerisation. In your answer you should explain, for each type: the kind and number of monomer(s) needed, what is produced, and how the atoms of the monomers end up in the products. (6 marks)

Ethane ($C_2H_6$C2​H6​) is a hydrocarbon found in natural gas. It undergoes complete combustion when burned in a plentiful supply of oxygen.

(a) Write a balanced symbol equation for the complete combustion of ethane. (2 marks)

(b) Ethane can also undergo incomplete combustion in a limited supply of oxygen. Name two products of incomplete combustion (other than water) and state why one of them is dangerous. (2 marks)

Long-chain hydrocarbons from crude oil are cracked to make smaller, more useful molecules. In one example, the alkane decane ($C_{10}H_{22}$C10​H22​) is cracked to form octane ($C_8H_{18}$C8​H18​) and one other molecule.

(a) Determine the formula of the other molecule produced, and state which homologous series it belongs to. (2 marks)

(b) Give one reason why cracking is economically important to an oil company. (1 mark)

The Earth's early atmosphere is thought to have been very different from the atmosphere today. The table compares the two.

Gas	Early atmosphere	Atmosphere today
Carbon dioxide	Very high (~95 %)	~0.04 %
Oxygen	Almost none	~21 %
Nitrogen	Small amount	~78 %

(a) Describe how the amount of carbon dioxide in the atmosphere decreased over time. Give one process responsible. (2 marks)

(b) Explain how the amount of oxygen in the atmosphere increased over time. (1 mark)

Ethanol is an alcohol that can be made industrially by reacting ethene with steam (water) in the presence of a catalyst. This reaction is called hydration and adds water across the C=C double bond.

The equation is: $C_2H_4 + H_2O \rightarrow C_2H_5OH$C2​H4​+H2​O→C2​H5​OH

Explain why this reaction is described as an addition reaction, and name the functional group present in ethanol. (2 marks)

Carbon dioxide and methane are described as greenhouse gases.

State what is meant by the term greenhouse gas. (1 mark)