1G2 Separation Techniques Assignment

8. 8. A sugar, raffinose, was treated with dilute hydrochloric acid. The resulting solution, Y, together with some known sugar solutions for reference, was analysed by chromatography. The following chromatogram was obtained.

What are the sugars present in solution Y?

• glucose and maltose

• glucose, galatose and fructose

• glucose, maltose and galatose.

• glucose, maltose and fructose.

1. 1. Name the processes that could be used to recover the underlined component in the pure form from each of the following mixtures:

(a) the different colourings used in making chocolate: ​ (a)  

(b) water from a sugar solution: ​ (b)  

(c) sand from the engine oil of the car: ​ (c)  

• chromatography
• distillation
• filtration
• evaporation to dryness
• magnetic attraction

3. 3. A sample of water contains salt as an impurity. The apparatus shown below is used to produce pure water from the sample.

(a) Suggest the purpose of the condenser.

ANSWER: To provide a ​ (a)   surface, to cool and ​ (b)   the water ​ (c)   into ​ (d)   water.

• condense
• vapour
• liquid
• cool

(b) What would be the approximate reading on the thermometer during the purification?

ANSWER: ................. ^oC

3(c) Draw a cross (x) on the diagram above on where the salt would be left after purification is complete.

4. The diagram shows a chromatogram obtained from three single dyes (blue, green and red) which are safe to consume. and four other unknown solutions (A, B, C and D).

(a) Which of the solutions, A, B, C or D

(i) ​ is pure ​ (a)  
(ii) contains green and red dye only? ​ (b)  

(iii) is most likely unsafe to be consumed? ​ (c)  

• B
• C
• D
• A

4(b) Why is the starting line drawn in pencil and not in ink?

ANSWER: Pencil lead is ​ (a)   in most solvents while ink is ​ (b)   in most solvents, so it will not ​ (c)   into the ​ (d)   and interfere with the results of the experiment.

• insoluble
• soluble
• dissolve
• solvent

4(c) Suggest a reason why the blue dye moves further up the chromatogram compared to the green dye.

ANSWER: The blue dye is ​ (a)   in the solvent than the green dye. Hence the blue dye travels ​ (b)   and further from the ​ (c)   .

• more soluble
• faster
• starting line
• less soluble