TAG A/A* Literacy, Connectives, Planning and the Big-mark Questions to Secure A*-A with Mrs Morey

1-2 marks: 2 comparisons – 2 comments given about each process with a reason. 2 marks awarded as comments lack detail. Answer 1: The UK is a rural country so there is lots of readily available plants and it is more sustainable than using ethene from crude oil. The UK also has naturally low temperatures whereas hydration needs temperatures of 300 o C, there’s also less energy needed in fermentation. But in fermentation you only get 51% and its impure. Therefore I do think fermentation is best for the UK.

3-4 = max of two advantages for hydration; vague disadvantage for hydration; vague disadvantage for fermentation. 3 marks awarded. Answer 2: Hydration needs crude oil which is a finite resource that won’t last forever but is made by continuous manufacture which means that ethanol is made quicker. However, more energy is needed for the reaction to take place but the rate is faster. No fractional distillation is needed to make the product unlike in fermentation which is impure. Hydration also has a higher atom economy than fermentation which means that more of the atoms are reacted and made into product. I think that hydration is a more efficient method of making ethanol

Answer 3: Hydration uses a continuous process which produces ethanol a lot faster than the fermentation batch process. Hydration also has a much higher atom economy of 100% compared to fermentation which is 51%, and the ethanol produced is pure, unlike the ethanol produced by fermentation which has to be purified. However, hydration uses non-renewable materials and the conditions require a lot of energy which is expensive. Overall I think hydration is best as it is faster, has 100% atom economy, does not pollute the environment, and produces pure ethanol. 5-6 = at least one advantage and one disadvantage for hydration; at least one disadvantage of fermentation; justifies best process. 5 marks awarded – no advantage given for fermentation.