SC1/2 - States of Matter / Separating & Purifying Substances

Question 1

What are the 3 states of matter?

Answer 1

Solid
Liquid
Gas

Question 2

What are the particle arrangments and movement of each of the 3 states?

Answer 2

Solid - tightly packed, regular arrangement and they vibrate around a fixed position

Question 3

What is it called when:
1 - Solid → Liquid
2 - Liquid → Gas
3 - Gas → Liquid
4 - Liquid → Solid
5- Gas → Solid
6 - Solid → Gas

Answer 3

1. Melting
2. Evaporation
3. Condensation
4. Freezing
5. Deposition
6. Sublimation

Question 4

What are the forces which have to be overcome to achieve a state change?

Answer 4

Force of attraction

Question 5

What is a substance which can’t be changed and is the same in all parts of it?

Answer 5

Pure

Question 6

What is a substance made of elements or compounds chemically joined together and can be separated using physical methods?

Answer 6

Mixture

Question 7

What are examples of mixtures?

Answer 7

Juice
Chocolate
Cake

Question 8

Exam Q - Explain why mixtures have a range of melting points but pure substances have precise melting points (2 marks)

Answer 8

Mixtures have different substances inside them, and each one has a different melting point whereas, in a pure substance, there is only one type of element or compound which is chemically bound, so it has precise melting and boiling points.

Question 9

What can be used to separate mixtures from insoluble substances?

Answer 9

Filtration

Question 10

What is a mixture made of solutes (dissolved substances) in a solvent?

Answer 10

Solution

Question 11

What is crystallisation?

Answer 11

When the solvent is evaporated out of the solution, leaving behind solutes.

Question 12

What is it called when a solution contains the maximum amount of solute that can dissolve in the solvent?

Answer 12

A saturated solution.

Question 13

What is chromatography?

Answer 13

When you separate coloured substances of a mixture.

Question 14

What is the mobile and stationary phase?

Answer 14

Mobile - The solvent
Stationary - Part of paper where the solvent moves up.

Question 14

How do you calculate the Rf value?

Answer 14

distance moved by spot / distance moved by solvent

Question 14

What are the 3 uses of chromatography?

Answer 14

To identify different substances by calculating the Rf.
Distinguish between our and impure substances.
Identify substance by comparing it to other patterns of known ones

Question 14

What 2 ways are there to produce pure water in a lab?

Answer 14

Simple still
Distillation

Question 15

What is fractional distillation?

Answer 15

When a fractional column is connected to a distillation setup to separate 2 or more liquids with different boiling points. The liquids with lower boiling points travel up the column first as it get hotter, letting you separate the liquids.

Question 15

How does a simple still work?

Answer 15

By heating liquid water and evaporating the pure water into another tube to condense it. It is not very efficient as lots of water is lost

Question 15

How does a distillation work?

Answer 15

By heating the liquid water (with anti-bumping granules) and evaporating it into a condenser which efficiently cools it down with minimal loss of water. The water is condensed and goes to a flask.-

Question 16

What are the uses of fractional distillation?

Answer 16

It is used in separating crude oil
Making alcohol
Separate gases in the air like liquid air.

Question 16

What are the stages of making water safe to drink?

Answer 16

Sieve out all the big pieces
Sedimentation - small particles settle down
Filtration - sand and gravel to get rid of soluble substances
Chlorination - disinfect the water