Separation and Solubility

Question 1

Solute

Answer 1

The substance which dissolves

Question 2

Solvent

Answer 2

The liquid in which a solute dissolves

Question 3

Solution

Answer 3

The mixture produced when a solute dissolves in a solvent

Question 4

Dissolve

Answer 4

When the solvent “breaks” apart the solute particles to form a solution

Question 5

Soluble

Answer 5

A substance which will dissolve in a solvent

Question 6

Insoluble

Answer 6

A substance which will not dissolve in a solvent

Question 7

Saturated

Answer 7

A solution containing the maximum amount of a solute at a particular temperature

Question 8

Suspension

Answer 8

Bits of solid remains (sediment) suspended in the liquid until they settle at the bottom

Question 9

Solubility

Answer 9

The mass of a solute which will dissolve in 100 g of water at a certain temperature

Question 10

Filtration

Answer 10

Filtering is used to separate small solid particles from a liquid.
eg. Separating dirt from I’m water by filtering.
The dirty what is poured through a piece of filter paper. Water particles pass through the tiny holes in the filter paper. The particles of dirt, which are larger than the particles of water , get stuck in the holes and do not go through.
When the process is finished the dirt is trapped in the filter paper and clear water has dripped through into the beaker below.
Any liquid that has been filtered is known as the filtrate.

Question 11

Evaporation

Answer 11

Evaporation is used when we want to get back a substance that has been dissolved.
eg. Getting salt out of salty water.
The salty water is put into an evaporating basin (or any shallow dish such as a saucer).
It is left in a warm place and the water evaporates leaving behind the salt crystals.
We see the salt crystals starting to form at the edge of the salty water but eventually all the water will go leaving behind just the salt.

Question 12

Distillation

Answer 12

It is used to separate a solvent from its solution
e.g. we can get a pure water from salty sea water. The solute (salt) will be left behind.
When the solution is heated, the solvent boils off as a gas. This gas is cooled down using a Liebig condenser and turned back into a liquid.

Question 13

Chromatography

Answer 13

Chromatography can be used to separate mixtures of coloured compounds.
Simple chromatography carried out on paper. A spot of the mixture (e.g. Ink) is placed near the bottom on the piece of chromatography paper and the paper is then placed upright in a suitable solvemy like water or ethanal.
As the solvent soaks up the paper it carries the mixture with it. Different components of the mixture move at different rates. This separate the mixture out.
For ink, different dyes travel different distances up the paper. The most soluble component of a mixture travels furthest up the paper and the least soluble is in the lowest position on the paper.
The solvent travels further up the filter paper leaving a line called the solvent front.

Question 14

Dissolving salt

What happens to the particles?

Answer 14

The particles in salt are held together in a fixed arrangement. The particles in water can move around. When the salt dissolves, the salt particles are not held together any more. They mix with water particles to form a solution. The mass of the water is 100g and salt is 10g, the solution will be 110 g if we had 20 g of salt in the water the solution would have been 120 g. This is called conservation of mass.
If 10cm3 os salt was but in 100cm3 of water the volume would be 100cm3 as the salt fills in the gaps between the water particles. This doesn’t crease the amount of water so the volume is the same.