CAIE IGCSE Chemistry Separation and Purification Methods

Practise selecting filtration, crystallisation, simple distillation or fractional distillation by linking each method to the mixture being separated.

Exam points

use filtration to separate an insoluble solid from a liquid and crystallisation for a soluble solid
use simple distillation to collect a solvent from a solution and cool vapour in a condenser
use fractional distillation to separate miscible liquids whose boiling points are different

[Maximum number: 1]

The chemical equation for the complete combustion of ethanol, $\mathrm{C}_{2} \mathrm{H}_{5} \mathrm{OH}$ , is shown.

\mathrm{C}_{2} \mathrm{H}_{5} \mathrm{OH}+3 \mathrm{O}_{2} \rightarrow 2 \mathrm{CO}_{2}+3 \mathrm{H}_{2} \mathrm{O}

The energy released when one mole of ethanol undergoes complete combustion is 1280 kJ .
Part of the energy level diagram for this reaction is shown.

Ethanol can also be manufactured by the fermentation of glucose, $\mathrm{C}_{6} \mathrm{H}_{12} \mathrm{O}_{6}$ .

Suggest the name of a process to obtain ethanol from a mixture of ethanol and water.

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