1. Answers to Worksheet, Separation Techniques
1. B C
2. C C
3. B
4. C
5. D
6. B
7. D
8. C
9. B
10. B

2. Section B Q1
chromatography
Fractional distillation (separating miscible liq with different bp)
Chromatography
Distillation (getting solvent from a mixture)
Use of a separating funnel (separating immiscible liquids)
Crystallisation

3. Section B Q2 a)
Water out
Water in
ii) To ensure smooth boiling of the liquid.

4. Section B Q2 b)
Ethanol starts to distil
100/C
Water starts to distil
78 /C
End of distillation of ethanol
c) The top of the receiver should not be stoppered/corked.

5. Section B Q2 (d)
The boiling pts of ethanol and water are 78C and 100 C respectively. In the experimental set up the
vapour from the boiling mixture of ethanol and water in the flask contains a
higher percentage of lower bp ethanol. As the vapour moves up the fractionating column, it repeatedly
condenses and boils inside the column. Each time the mixture boils, the % of the lower bp ethanol
increases. By the time the vapour reaches the top of the fractionating column, it has become almost pure
ethanol.

6. Section B Q2 (d) (cont’d)
This vapour then passes into the condenser where it is
cooled and condenses into
liquid ethanol. The thermometer shows a constant temperature of
78C when the ethanol is being distilled. The water, which has a higher bp, remains in the flask until almost all the ethanol has distilled.
In this experiment,
complete/total separation is not effected. The distillate contains a very large % of ethanol and a little water.

7. Section B Q4
Fruit juice X contains sucrose.
It does not contain maltose
It contains a sugar that is not sucrose, maltose or glucose.
Label the 3 sugars as (1), (2) and (3) such that sugar (1) is closest to the starting line and (3) the furthest.
Rf of sugar (1) = 0.7/4.3 = 0.16
Rf of sugar (2) = 2.4/4.3 = 0.56
Rf of sugar (3) = 3.7/4.3 = 0.86
c) Sucrose (closest match to 0.16), glucose and fructose