CC2: States Of Matter And Mixtures

Question 1

Describe a solid

Answer 1

Low energy/Small vibrations/rigid lattice structure/strong forces of attraction between particles/definite shape and volume/when heat applied it vibrates more, bonds begin to loosen/expand slightly when heated

Question 2

Describe a liquid

Answer 2

Bonds less strong/free to move and roll over each other/expands when heated/vibrates more than solids/higher energy/takes shape of container/fixed volume/the hotter the faster the particles move

Question 3

Describe a gas

Answer 3

High energy/no forces of attraction between them/fill up any container/ no fixed shape or volume/can be compressed/when heat is applied it can have higher pressure or expand

Question 4

Melting

Answer 4

When heat is applied to a solid and the particles vibrate, weakening them and making the solid expand. At a certain temperature the particles can break free from their positions.

Question 5

Boiling

Answer 5

When more heat is applied and eventually the particles’ bonds break free completely and the liquid turns to a high energy gas

Question 6

Desposition

Answer 6

From gas to a solid. Requires lots of energy

Question 7

Condensation

Answer 7

Gas to liquid- needs to cool and lose heat energy

Question 8

Evaporation

Answer 8

Liquid to gas

Question 9

Sublimation

Answer 9

Solid to gas- requires lots of energy

Question 10

What is a physical reaction?

Answer 10

A change in state, often reversible

Question 11

What is a chemical reaction?

Answer 11

Change in structure- when atoms swap round and reactants can be reacted to for, different products. This can often be hard to reverse or irreversible

Question 12

What is a homogenous mixture?

Answer 12

A mixture where only one thing can be seen eg seawater

Question 13

What is a heterogeneous mixture?

Answer 13

A mixture where many components to the mixture can be seen eg sand in water

Question 14

How can we separate homogenous mixtures?

Answer 14

Simple/fractional distillation or crystallisation

Question 15

How can we separate heterogenous mixtures?

Answer 15

Through filtration

Then go on to distillation etc

Question 16

What is the meaning of pure?

Answer 16

Containing one single element or compound throughout the structure eg pure gold is just gold atoms

Question 17

How can we test if a substance is pure?

Answer 17

Melt it: if it has a melting point range it is an impure mixture, if it has one sharp melting point it is pure eg pure water has a boiling point of 100 degrees c

Question 18

Give an example of simple distillation

Answer 18

Saltwater.

Heat it. Water will evaporate at 100 degrees c and rise as a vapour and go down the cooling tube with cold water running through it which will condense the vapour which will run into a flask.

Leave the salt to dry and it will crystallise.

Question 19

Fractional distillation

Answer 19

Used when the range of boiling points in the mixture are very similar.
They separate off in the fractionating column- bigger molecules with higher boiling points condense and leave at the bottom which is hotter and the smaller molecules with lower boiling points leave and condense at the cool top of the column.

Question 20

Give two examples of fractional distillation

Answer 20

Crude oil

Air

Question 21

How do you fractionally distill air?

Answer 21

Liquefaction and fractional distillation

Cool to -200 for all gases to be liquified and slowly heat them to turn into gas and condense them again

Question 22

Filtration

Answer 22

Using filter paper to separate insoluble particles from liquid

Question 23

Crystallisation

Answer 23

Separates soluble solid from a solution

Question 24

How to crystallise a product?

Answer 24

Heat your solution in an evaporating dish. The solvent should evaporate and the solution will get more concentrated.

Crystals may start to form when the water has gone.

The salt should form an insoluble crystal solid. You can filter them out and leave them to dry.

Question 25

Mobile phase

Answer 25

The solvent- either liquid or gas

Question 26

Stationary phase

Answer 26

Where molecules can't move eg paper in paper chromatography- either a solid or a thick liquid

Question 27

Describe paper chromatography

Answer 27

Stationary phase- piece of paper Mobile phase- water/ethanol Draw line on the bottom of the paper with pencil so pen ink isn't mixed Put a spot of mixture onto the line- not under as it could dissolve in the solvent straight away. Put the paper in the mobile phase UNDER the line as otherwise the mixture could dissolve The solvent will start to move up the paper and the chemicals in the mixture will separate and move up the paper

Question 28

What does it mean if a spot stays on the line?

Answer 28

It is insoluble

Question 29

What happens with molecules with higher solubility?

Answer 29

Spend more time in the mobile phase and carried further up paper

Question 30

What are 2 factors for a long time spent on each phase?

Answer 30

How attracted to the stationary phase the chemicals are How soluble they are in the solvent

Question 31

Rf Value

Answer 31

Distance travelled by solute/distance travelled by solvent | Always under 1

Question 32

Locating agent

Answer 32

Spray to find colourless solutes in the mixture eg amino acids

Question 33

What is a standard reference material?

Answer 33

A pure substance to check identity of mixture's components (basically check it there are any same in it eg black ink next to black ink u get me)

Question 34

What can u use chromatography for?

Answer 34

``` Separating mixtures Checking solubility (won't move if insoluble) Checking purity (won't separate if pure) ```

Question 35

3 sources of water

Answer 35

Surface water Ground water Waste water

Question 36

Surface water

Answer 36

Lakes, rivers, reservoirs- not very pure, needs to be treated well

Question 37

Ground water

Answer 37

From aquifers (rocks in ground that trap water)- relatively pure

Question 38

Waste water

Answer 38

By-product of industrial processes etc | Needs to be treated very well as it was contaminated

Question 39

3 steps to water treatment

Answer 39

Filtration Sedimentation Chlorination

Question 40

Filtration

Answer 40

Filter water through metal mesh to get rid of large insoluble sediment eg rocks and twigs

Question 41

Sedimentation

Answer 41

Use iron sulphate or aluminium sulphate to make fine sediment clump together which can then be filtered out

Question 42

Chlorination

Answer 42

Bubble chlorine gas through the water which kills harmful microbes

Question 43

Potable

Answer 43

Fit to drink

Question 44

How else can potable water be obtained?

Answer 44

Distilling sea water through simple distillation

Question 45

What kind of water is ideal to use in a scientific experiment?

Answer 45

Distilled/deionised water. This is because all ions like calcium and iron and copper irons are not in this water and therefore cannot interfere with results.

Question 46

When is simple distillation used?

Answer 46

When the mixture has two very different boiling points

Question 47

When is fractional distillation used?

Answer 47

When the boiling point range is very close/ has similar boiling points

Question 48

What is fractional distillation performed in?

Answer 48

A fractionating column

Question 49

Differences between pure substances and mixtures

Answer 49

Pure- one m/b point Mixture- m/b point range Pure- one single element/compound throughout Mixture- a mixture of elements/compounds