Edexcel IGCSEChemistryGeneral Applications10 Marks
This question is about organic chemistry. (a) Ethanol can be produced by the fermentation of glucose. (i) Name the catalyst used in this reaction.
- (a)(i)Name the catalyst used in this reaction.[1]
- (a)(ii)State the optimum temperature for fermentation.[1]
- (a)(iii)Explain why this reaction is carried out in the absence of air.[2]
- (b)Ethanol can also be produced by the hydration of ethene. (i) Write the word equation for the hydration of ethene.[1]
- (b)(ii)State the conditions required for the hydration of ethene.[2]
- (c)Ethene is an unsaturated hydrocarbon. (i) Describe a chemical test to show that ethene is unsaturated.[2]
- (c)(ii)Draw the displayed formula of ethene.[1]
Mark scheme
Marking points from the official mark scheme. The mark or mark type is shown in brackets.
- B1 for (a)(i) yeast / zymase
- B1 for (a)(ii) 25-37 °C / around 30 °C
- M1 for (a)(iii) to prevent oxidation of ethanol / formation of ethanoic acid
- A1 for (a)(iii) by air / oxygen
- B1 for (b)(i) ethene + steam / water → ethanol
- M1 for (b)(ii) high temperature (300 °C) / high pressure (60-70 atm)
- A1 for (b)(ii) phosphoric acid catalyst
- M1 for (c)(i) add bromine water / aqueous bromine
- A1 for (c)(i) orange/brown/yellow colour changes to colourless
- B1 for (c)(ii) Correct displayed formula of ethene (C=C double bond, 2 H atoms on each C)
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