Separating mixtures

Question 1

What are the differences between a compound and a mixture?

Answer 1

-Compounds have a fixed composition (ratio of elements)

-Mixtures have no fixed composition (proportions vary)

-Chemical reactions must be used to separate compounds

-The different elements can be separated by physical means, using the different properties of each substance in the mixture

-There are chemical bonds between the different atoms /molecules in the compound

-There are no chemical bonds between different atoms/molecules in the mixture

Question 2

What are the 5 methods of separating mixtures?

Answer 2

-Filtration

-Crystallisation

-Distillation

-Chromatography

-Magnetic attraction

Question 3

How do you choose which method to use?

Answer 3

Each method relies on differences in the physical properties of the substances in the mixture, such as different solubilities in a solvent or different boiling points.

Question 4

What is filtration?

Answer 4

Separating insoluble solids from a liquid using filter paper

Question 5

What is crystallisation?

Answer 5

Separating soluble solids from a liquid by evaporating the liquid in a wide dish that has a high surface area for fast evaporation

Question 6

What are the 2 types of distillation?

Answer 6

Simple distillation and fractional distillation

Question 7

What is simple distillation?

Answer 7

When a solution is boiled and the vapour goes into a condenser (a tube surrounded by water that cools the vapour) and liquid comes out the other end to be collected

Question 8

What is fractional distillation?

Answer 8

A process used to separate mixtures of substances with different boiling points by starting at the lowest boiling point, collecting the vapour then repeating

Question 9

What is paper chromatography?

Answer 9

A piece of chromatography paper with different substances drawn onto it has its bottom dipped into water and as the water climbs the paper, the more soluble substances move further up the paper

Question 10

What is filtration used for?

Answer 10

To separate an insoluble solid from a liquid

Question 11

What is crystallisation used for?

Answer 11

To separate a soluble solid from a solution

Question 12

What is simple distillation used for?

Answer 12

Separating a liquid from a solution

Question 13

What is fractional distillation used for?

Answer 13

To separate a mixture of liquids with different boiling points

Question 14

What is chromatography used for?

Answer 14

To separate the different soluble, coloured components of a mixture