Page 27 - Ranger SPM 2022 Chemistry

Chemistry SPM Chapter 2 Carbon Compound
Alcohol
1. Preparation of alcohol through two chemical reactions:
(a) Fermentation
• Carbohydrate which is sugar or starch undergoes fermentation in the
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absence of oxygen by using a catalyst called zymase enzyme (yeast) to
produce ethanol and carbon dioxide.
• C H O (aq) Zymase enzyme 2C H OH(l) + 2CO (g)
6
2
5
6
12
2
• Fractional distillation is carried out to produce pure ethanol.
Thermometer
Water out
Liebig
Fractionating condenser
column Filtered
fermentation
product
Water Water in

Glucose Limewater Ethanol,
solution Heat C H OH
2
5
+ yeast
(a) Set up of apparatus for fermentation (b) Set up of apparatus for distillation
Diagram 2.8
Type of Apparatus Observation
carbohydrate set-up
Rice • Colourless bubbles are observed in the fermentation solution.
(a)
• Colourless bubbles turn limewater cloudy.
(b) • The distillate is a colourless liquid and has a sharp smell.
Pineapple juice • Colourless bubbles are observed in the fermentation solution.
(a)
• Colourless bubbles turn limewater cloudy.
(b) • Distillate formed is a colourless liquid and has a sharp smell.

• Equation for the organic molecules to simple
fermentation of rice and compounds.
Form 5
pineapple juice: • The mixture solution must
C H O (l) → 2C H OH(l) be placed in a closed conical
6
5
6
12
2
+ 2CO (g) flask because fermentation
2
• Glucose fermentation will is an anaerobic process.
produce ethanol and carbon • Presence of oxygen during
dioxide. fermentation oxidises
• Yeast is added into rice ethanol to ethanoic acid.
and pineapple solution to • Enzyme zymase denatures at
produce zymase enzyme the end of the fermentation
that can convert complex when the percentage of
ethanol increases to 14%.
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02.5 RANGER SPM CHEMISTRY 2P.indd 156 29/03/2022 2:28 PM