Separation Techniques

Question 1

What is a solute?

Answer 1

The substance that is dissolved in a liquid
Example: salt in salt water

Question 2

What is a solvent?

Answer 2

Liquid that dissolves the solute
Example: water in salt water

Question 3

What is a solution?

Answer 3

A mixture formed when a solute dissolves in a solvent
Example: salt water is a solution of salt (solute) in water (solvent)

Question 4

What are soluble and insoluble salts

Answer 4

Soluble salts are salts that dissolve in water
Insoluble salts are salts that do not dissolve in water

Question 5

What is filtration?

Answer 5

Filtration is used to separate an insoluble salt from a liquid.
The solid stays on the filter paper (called the residue) and the liquid passes through (called the filtrate).
Example: separating sand (insoluble salt) from water.

Question 6

What is evaporation?

Answer 6

Used to recover a soluble salt from a solution by removing the solvent (water) through heating.
The salt remains behind as the water evaporates.
Example: getting salt crystals from salt water.

Question 7

What is crystallisation?

Answer 7

Crystallisation is a method used to make pure crystals of a soluble salt from a solution. This technique is often used in the lab to make salts like copper(Il) sulfate.

Question 8

What are the steps of crystallisation ?

Answer 8

1. React thé acid with an insoluble base
2. Stir and warm the mixture
3. Filter thé mixture
4. Evaporate some water
5. Leave the solution to cool
6. Dry the crystals