Alcohols
6 marks · NormalA student carries out two experiments: (A) heating ethanol with potassium dichromate(VI) in dilute sulfuric acid, and (B) producing ethanol by fermentation.
In experiment A, state the colour change that occurs when ethanol is successfully oxidised.
Name the final organic product formed in experiment A.
In experiment B, yeast is added to a sugar solution. State one condition required to maximise ethanol production by fermentation.
Complete the table below for each experiment.
| Experiment | Reactants | Product |
|---|---|---|
| A | ||
| B |
Work this out on paper, then compare with the answer and worked solution below. With a free account you can submit written answers for marking.
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(a) Orange to green
(b) Ethanoic acid
(c) Warm temperature (about 30°C) OR absence of air (anaerobic) OR use of yeast
(d) A: Reactants: ethanol, potassium dichromate(VI), dilute sulfuric acid | Product: ethanoic acid B: Reactants: sugar (or glucose), yeast | Product: ethanol · must show A: ethanol, potassium dichromate(VI), dilute sulfuric acid, ethanoic acid, B: sugar (or glucose), yeast, ethanol
Show mark scheme and worked solution
Marking points
B1 (a) · 1 mark · Correctly states 'orange to green' colour change.
B2 (b) · 1 mark · Correctly names ethanoic acid as the product.
B3 (c) · 1 mark · States one suitable condition for fermentation (e.g. warm temperature, absence of air, use of yeast).
B4 (d) · 1 mark · Fills in correct reactants for experiment A.
B5 (d) · 1 mark · Fills in correct product for experiment A.
B6 (d) · 1 mark · Fills in correct reactants and product for experiment B.
Worked solution
(a) The solution changes from orange to green.
(b) The final organic product is ethanoic acid.
(c) One suitable condition: a warm temperature around 30°C.
| Experiment | Reactants | Product |
|---|---|---|
| A | ethanol, potassium dichromate(VI), dilute sulfuric acid | ethanoic acid |
| B | sugar (or glucose), yeast | ethanol |