SC2a Methods of Separating and Purifying Substances

Question 1

Filtration?

Answer 1

Insoluble particles get trapped in the filter paper, soluble particles go through the filter paper.​

Question 2

Crystallisation?

Answer 2

The solution is heated and the solvent (water) evaporates and the soluble solid forms crystals.​

Question 3

Simple distillation?

Answer 3

A mixture of 2 soluble substances is heated so that one evaporates, cools and condenses. ​

Question 4

Fractional distillation?

Answer 4

A mixture of more than 2 soluble substances is heated. The one with the lowest boiling point evaporates, cools and condenses. ​

Question 5

Chromatography?

Answer 5

A mixture of soluble dyes are separated by adding a solvent chromatography paper. ​

Question 6

How does paper chromatography work?

Answer 6

solvent moves along a strip of paper, it carries the different substances in the mixture at different speeds, so they are separated.

Question 7

Mobile phase on paper chromatography?

Answer 7

the solvent

Question 8

Stationary phase on paper chromatography?

Answer 8

the paper

Question 9

Rf=

Answer 9

distance moved by spot / distance moved by solvent

Question 10

Steps for purifying water in order.

Answer 10

~sieving
~sedimentation
~filtration
~chlorination

Question 11

sieving?

Answer 11

removes twigs and leaves.

Question 12

sedimentation?

Answer 12

Large, insoluble particles such as stones fall to the bottom and settle out.​

Question 13

filtration?

Answer 13

insoluble partiles are trapped in filter paper and soluble particles go through the filter paper.

Question 14

chlorination?

Answer 14

Chlorine is added to kill any microorganisms and sterilise the water.