2 (a) (i) Ethanol is produced from ethene by hydration in the presence of a catalyst - AQA - GCSE Chemistry - Question 2 - 2014 - Paper 1

The solid waste yeast can be removed by a process called filtration. This involves passing the mixture through a filter that allows the liquid (containing ethanol) to pass through while trapping the solid yeast on the filter.

Ethanol can be extracted from the solution through distillation. This process involves heating the solution to evaporate the ethanol, which has a lower boiling point than water. The vapor is then condensed back into liquid form, yielding purified ethanol.

Biodiesel produces less carbon dioxide and has no sulfur dioxide emissions, which contributes to cleaner air. It is more sustainable and renewable, as it can be produced from crops, which can be replanted each year. Furthermore, it helps in reducing dependence on fossil fuels.

However, biodiesel can produce more nitrogen oxides than petroleum diesel, potentially contributing to air pollution. The cultivation of crops for biodiesel may lead to deforestation and habitat destruction. Additionally, there may be competition for land between food crops and biofuel production, leading to food shortages.