Chemistry C2

Question 1

Course filtration definition

Answer 1

Water is passed through a course filter to remove leaves and twigs

Question 2

Sedimentation definition

Answer 2

A chemical added which causes tiny particles to clump together into larger particles. May or may not be able to be filtered.

Question 3

Fine filtration definition

Answer 3

Water is separated onto specially prepared layers of sand and gravel. As it trickles through, solids are removed

Question 4

Chlorine definition

Answer 4

Chlorine gas is injected into the water which kills all of the microbes.

Question 5

How can fractional distillation be used? (3)

Answer 5

• Separate different products in crude oil
• To make alcoholic drinks such as whisky and vodka
• To separate gases in the air after air has cooled and turned into a liquid at -200 Degrees Celsius

Question 6

What happens to vapour when it is condensed?

Answer 6

It turns back into liquid water again and will now be pure water

Question 7

What is distillation?

Answer 7

Evaporation followed by condensation

Question 8

What happens when mineral water evaporates?

Answer 8

Turns into gas (vapour). The solid minerals, much higher boiling points, are left behind. The water is now pure

Question 9

Can distillation be used to separate 2 or more liquids?

Answer 9

Yes because some liquids boil more easily than others. Liquids with lower boiling points evaporate more easily than others and will turn to vapour first.

Question 10

What is paper chromatography used for?

Answer 10

• Distinguish between pure and impure substances.
• Identity substances by comparing pattern on chromatogramme with patterns formed by substances
• Identify substances by calculating their R values

Question 11

How does paper chromatography work?

Answer 11

Paper is placed in a solvent with samples already in it. The solvent soaks up through the paper leaving coloured marks of what is in the mixture.

Question 12

What is chromatography?

Answer 12

A method of finding out which colour compounds and chemicals a mixture contains.

Question 13

At what temperature does a solid become a liquid?

Answer 13

At its melting point

Question 14

True or false:

Do solids gain energy when melting?

Answer 14

Yes, they gain lots of energy when melting

Question 15

What can a mixture contain?

Answer 15

A mixture can contain elements and/or compounds that are not chemically joined.

Question 16

How can you separate mixtures?

Answer 16

There is one way you can separate mixtures, it is called physical process.

Question 17

Name the composition of a pure substance? (2)

Answer 17

• Same in all parts of a piece of the substance

- Can’t be changed. Eg. Gold can only contain gold atoms

Question 18

How to get from:

• Gases to liquids?
• Liquids to gases?
• Liquids to solids?
• Solids to liquids?
• Solids to gases?
• Gases to solids?

Answer 18

Gases to liquids = condensation 
Liquids to gases = evaporation
Liquid to solid = freezing 
Solid to liquid = melting 
Solid to gases = sublimation 
Gases to solid = deposition