Solubility

Question 1

Solvent

Answer 1

The liquid

Question 2

Solute

Answer 2

The solid

Question 3

Soluble

Answer 3

Dissolvable

Question 4

Insoluble

Answer 4

Not dissolvable

Question 5

Why is water the most common solvent used?

Answer 5

It’s easily available, cheap and dissolves many different solids.

Question 6

A saturated solution

Answer 6

A solution that cannot dissolve any more solute because too much of it has been added. This can be fixed by adding more solvent or increasing temperature.

Question 7

Salt is a solid which —— in water

Answer 7

Dissolves

Question 8

Salt water is a ——

Answer 8

Solution

Question 9

Other dissolvable substances

Answer 9

Sugar, instant coffee

Question 10

What is a solution?

Answer 10

The mixture produced when a solute dissolves in a solvent.

Question 11

What is a mixture?

Answer 11

Substances that are not chemically combined.

Question 12

Define dissolve

Answer 12

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

Question 13

Define supspension

Answer 13

When the solid is evenly spread throughout the liquid… will eventually sink but is makes the solution go cloudy

Question 14

Define sediment

Answer 14

Solid particles sit at the bottom of the liquid… not mixing

Question 15

Explain the process of filtration

Answer 15

Separating a solid from a liquid by filtering the solution so the solid stays and liquid goes.

Question 16

Solubility Rules

Answer 16

All compounds that contain sodium, potassium and ammonium are soluble
All nitrates are soluble
Most sulphates are soluble (exceptions: silver sulphate, barium sulphate, calcium sulphate & lead sulphate)
Most chlorides are soluble (exceptions: silver chloride and lead chloride)
Most carbonates, oxides and hydroxides are insoluble (exceptions: sodium, potassium and ammonium compounds)

Question 17

Why does coffee dissolve better in hot than cold?

Answer 17

Because the particles move more vigorously when heated

Question 18

Explain evaporation

Answer 18

The salty water is put in an evaporation basin. Left in warm place where water evaporates and leaves salt crystals.

Question 19

Explain purifying rock salt

Answer 19

Dissolve rock salt in water
Filter to remove rock
Evaporate water to get pure, dry salt

Question 20

Where can you lose salt in the process or purifying rock salt

Answer 20

Some of the salt is sand
Some spits out
Some stays in the beaker

Question 21

Explain distillation

Answer 21

Distillation is used to separate.
It’s the process of heating a liquid solution to form vapour and then condensing it to get a liquid.
For example, if we have copper sulphate but we only want water or just the copper sulphate then we can separate it. First we heat it because the water will evaporate first. Then as the water has evaporated we condense it so it is a liquid but separate.

Question 22

Why will simple distillation not work if the difference between the 2 boiling points is less than 25 degrees?

Answer 22

Because the components don’t get separated and purified completely

Question 23

What is fractional distillation?

Answer 23

It is used for separating a mixture of liquids

Question 24

What is chromatography?

Answer 24

Can be used to separate mixtures of coloured compounds eg. Inks, colouring agents

Question 25

Explain chromatography

Answer 25

Take a piece of paper and draw a line near the bottom. On this line place spots of the mixture. Then place the paper upright in a suitable solvent eg water…
This solvent will soak up the paper and carry the mixtures with it. Different compounds will move at different rates - this will separate the colours out.

Question 26

The most soluble moves ———

Answer 26

The furthest up the paper

Question 27

The least soluble moves ———

Answer 27

The lowest on the paper.

Question 28

State 4 ways on how to separate a mixture

Answer 28

Using a sieve
Using a magnet
Filtering
Evaporation

Question 29

Why does sand not dissolve in water?

Answer 29

Because the bond in the water is not strong enough to dissolve the large particles.

Question 30

Explain saturation

Answer 30

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

Question 31

Conservation of mass

Answer 31

When the mass of the substance changes but the volume stays the same

Question 32

Aqueous

Answer 32

Solutions in which the solute is water