5. Separating Mixtures

Question 1

If a solid is described as ‘SOLUBLE’ what does this mean?

Answer 1

Question 2

Give four reasons why water is the most important solvent.

Answer 2

• Water (a solvent) dissolves more substances (solutes) than any other liquid
• It is safe
• It is cheap
• It is widely available

Question 3

What is water used for most in the home?

Answer 3

Washing demands more water than anything

Question 4

Why is water exceptionally useful as a solvent for this purpose?

Answer 4

It can dissolve many Stains.

Question 5

What can be added to water to make it a better solvent?

Answer 5

With a detergent it is an even more powerful cleaner

Question 6

Name three stains that water cannot dissolve.

Answer 6

• Chewing gum
• Car engine oil
• Nail varnish.

Question 7

Name a suitable solvent for each of these stains.

Answer 7

• Chewing gum - Trichloroethane
• Car engine oil - Paraffin
• Nail varnish - Acetone

Question 8

What term is used to describe cleaning without water?

Answer 8

Dry cleaning

Question 9

What is the difference between a concentrated or dilute solution?

Answer 9

Question 10

How could you turn a concentrated solution into a dilute solution?

Answer 10

Add more Solvent (water).

Question 11

How could you turn a dilute solution into a concentrated solution?

Answer 11

Add more Solute (Copper Sulfate)

Question 12

What is a saturated solution?

Answer 12

Question 13

How are copper sulphate crystals formed?

Answer 13

Crystals form when hot saturated solutions cool down. When the saturated solution is allowed to cool slowly, large crystals form but when the saturated solution is cooled rapidly, small crystals form.

Question 14

What are common features of crystals?

Answer 14

They all have smooth faces and sharp edges.

Question 15

What is the difference between Melting and Dissolving?

Answer 15

Question 16

What is the difference between an Element and a Compound?

Answer 16

Question 17

What is a PURE SUBSTANCE?

Answer 17

Question 18

What is a MIXTURE?

Answer 18

Question 19

Draw what you would expect to see in the pure substances boxes if this mixture was separated.

Answer 19

Question 20

What are the six techniques to separate a mixture?

Answer 20

• filtration
• evaporation
• chromatography
• separating funnel
• distillation
• magnets

Question 21

What is ‘Filtration’?

Answer 21

Question 22

What is ‘Evaporation’?

Answer 22

Question 23

What is ‘Chromatoraphy’?

Answer 23

Question 24

With ‘Chromatography’, which colours of M&Ms would you expect to be mixtures and which should be pure?

Answer 24

Question 25

What is the ‘Separating Funnel’ method to separate a mixture?

Answer 25

Question 26

What is ‘Distillation’?

Answer 26

Liquids that do mix are said to be **miscible**. E.g. Ethanol and water can be miscible that can be separated Distillation separates miscible liquids using their different boiling points.

Question 27

Can you describe the Distillation process to separate Ethanol from Water?

Answer 27

Question 28

Distillation - What is the purpose of the condenser?

Answer 28

To cool the gas so that it turns back to a liquid

Question 29

What would happen if the mixture was heated to 110 °C?

Answer 29

Both water and ethanol would evaporate together

Question 30

How are ‘Magnets’ used to separate mixtures?

Answer 30

A magnet can be used to separate magnetic metals e.g. Iron and Nickel

Question 31

| How would you separate the following mixture:

Answer 31

Pick them out

Question 32

How would you separate the following mixture:

Answer 32

Filtration - mud sticks to filter paper

Question 33

How would you separate the following mixture:

Answer 33

Chromatography

Question 34

How would you separate the following mixture:

Answer 34

Distillation

Question 35

How would you separate the following mixture:

Answer 35

Magnet - the iron can be separated from the mixture of iron and sulphur

Question 36

How would you separate the following mixture:

Answer 36

Chromatography

Question 37

Answer 37

Question 38

Answer 38

Question 39

Amy and her family visit the beach during the summer. Amy and her sister have a bucket containing seawater and sand. Sea water is a solution of salt in water. Using labelled diagrams, describe the two separation techniques Amy could use to collect pure samples of sand and water from the mixture in the bucket.

Answer 39

Question 40

Answer 40

Question 41

Answer 41

A pure substance will produce a single spot, whereas a mixture will show multiple spots.

Question 42

Answer 42