Separation techniques

Question 1

Define Pure Substance

Answer 1

A pure substance is made up of 1 single element or compound. It is not mixed with any other substances.

Question 2

What process is carried out to separate an insoluble solid from a liquid

Answer 2

Filtration

Question 3

What processes are used to separate a soluble solid from a liquid?

Answer 3

1. Evaporation to dryness
   OR
2. Crystallisation (If substance is not heat-stable)

Question 4

What processes are used to separate solids?

Answer 4

1. Using a suitable solvent (If only 1 is soluble)
   OR
2. Magnet (If only 1 is magnetic)
   OR
3. Sublimation (If it sublimes eg. iodine, dry ice)

Question 5

What process is used to separate a liquid from a solution

Answer 5

Simple distillation

Question 6

What process is used to separate immiscible liquids

Answer 6

Using a separating funnel

Question 7

Separating miscible liquids

Answer 7

Fractional distillation

Question 8

What is Rf value?

Answer 8

Distance travelled by substance (start line to spot) DIVIDED BY
Distance travelled by solvent (start line to solvent front)

Question 9

What decides the distance the chromatogram travels?

Answer 9

The solubility of the sample in the solvent.

Question 10

Why is locating agent added?

Answer 10

It is to make colourless spots visible. It reacts with substances on the paper to form coloured spots

Question 11

What is one reason for the importance of purity (in chromatogram) ?

Answer 11

Impurities in drugs and medicine may cause undesirable side effects.