2.2 (b)

Question 1

(C) What is paper chromatography?

Answer 1

It is a seperation method for a mixture of substances.

Question 2

(C) What does a chromatogram show?

Answer 2

It shows the constituents of a seperated mixture.

Question 3

(C) Name four methods of seperation and distillation.

Answer 3

Filtration
Crystallisation
Distillation
Fractional Distillation

Question 4

(C) Describe the process of filtration.

Answer 4

The liquid is passed through a filter paper placed in a funnel such that only the filtrate is able to pass through. The residue is left in the filter paper and has now been seperated from the liquid.

Question 5

(C) Describe the process of crystallisation.

Answer 5

The solution is heated so that water evaporates. Then to check if the solution is ready, it is placed on microsope slide. Crystals should form quickly on the cool glass. The solution is then passed through filter paper placed in a funnel and left to crystallize.

Question 6

(C) Describe the process of distillation.

Answer 6

In simple distillation a solvent is heated in a flask. it boils and the steam rises into the condenser. The condenser is cold so a liquid is formed which drips into the beaker.

Question 7

(C) What is the difference between distillation and fractional distillation?

Answer 7

Simple distillation is used to obtain the solvent from a solution. Fractional distillation is used to seperate a mixture of liquids from each other.

Question 8

(C) Why does the purity of a substance matter?

Answer 8

Unwanted substances could harm the consumer. For example unwanted substances in medical drugs could harm the patient.

Question 9

(E) A pure substance has a:

a) low melting and high boiling point
or
b) definite, sharp melting and boiling point.

Answer 9

b) definite, sharp melting and boiling point.

Question 10

(E) Using the boiling and melting point, how can a impurity be identified?

Answer 10

When a substance contains a impurity, its melting point falls and its boiling point rises. These temperatures are no longer sharp however fall within a certain range. The more impure a substance is, the bigger the change in melting and boiling point and the wider the temperature range over which the substance melts and boils.

Question 11

(E) Filtration is used to seperate a :

a) solid from a liquid
b) solvent from a solution
c) mixture of substances.

Answer 11

a) solid from a liquid