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External Revision: Chemistry > CC2: States Of Matter And Mixtures > Flashcards

CC2: States Of Matter And Mixtures Flashcards

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1
Q

Describe a solid

A

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

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2
Q

Describe a liquid

A

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

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3
Q

Describe a gas

A

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

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4
Q

Melting

A

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.

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5
Q

Boiling

A

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

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6
Q

Desposition

A

From gas to a solid. Requires lots of energy

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7
Q

Condensation

A

Gas to liquid- needs to cool and lose heat energy

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8
Q

Evaporation

A

Liquid to gas

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9
Q

Sublimation

A

Solid to gas- requires lots of energy

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10
Q

What is a physical reaction?

A

A change in state, often reversible

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11
Q

What is a chemical reaction?

A

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

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12
Q

What is a homogenous mixture?

A

A mixture where only one thing can be seen eg seawater

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13
Q

What is a heterogeneous mixture?

A

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

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14
Q

How can we separate homogenous mixtures?

A

Simple/fractional distillation or crystallisation

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15
Q

How can we separate heterogenous mixtures?

A

Through filtration

Then go on to distillation etc

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16
Q

What is the meaning of pure?

A

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

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17
Q

How can we test if a substance is pure?

A

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

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18
Q

Give an example of simple distillation

A

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.

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19
Q

Fractional distillation

A

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.

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20
Q

Give two examples of fractional distillation

A

Crude oil

Air

21
Q

How do you fractionally distill air?

A

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

22
Q

Filtration

A

Using filter paper to separate insoluble particles from liquid

23
Q

Crystallisation

A

Separates soluble solid from a solution

24
Q

How to crystallise a product?

A

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.

25
Q

Mobile phase

A

The solvent- either liquid or gas

26
Q

Stationary phase

A

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

27
Q

Describe paper chromatography

A

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

28
Q

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

A

It is insoluble

29
Q

What happens with molecules with higher solubility?

A

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

30
Q

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

A

How attracted to the stationary phase the chemicals are

How soluble they are in the solvent

31
Q

Rf Value

A

Distance travelled by solute/distance travelled by solvent

Always under 1

32
Q

Locating agent

A

Spray to find colourless solutes in the mixture eg amino acids

33
Q

What is a standard reference material?

A

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)

34
Q

What can u use chromatography for?

A 
Separating mixtures
Checking solubility (won't move if insoluble)
Checking purity (won't separate if pure)
35
Q

3 sources of water

A

Surface water
Ground water
Waste water

36
Q

Surface water

A

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

37
Q

Ground water

A

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

38
Q

Waste water

A

By-product of industrial processes etc

Needs to be treated very well as it was contaminated

39
Q

3 steps to water treatment

A

Filtration
Sedimentation
Chlorination

40
Q

Filtration

A

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

41
Q

Sedimentation

A

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

42
Q

Chlorination

A

Bubble chlorine gas through the water which kills harmful microbes

43
Q

Potable

A

Fit to drink

44
Q

How else can potable water be obtained?

A

Distilling sea water through simple distillation

45
Q

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

A

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.

46
Q

When is simple distillation used?

A

When the mixture has two very different boiling points

47
Q

When is fractional distillation used?

A

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

48
Q

What is fractional distillation performed in?

A

A fractionating column

49
Q

Differences between pure substances and mixtures

A

Pure- one m/b point
Mixture- m/b point range

Pure- one single element/compound throughout
Mixture- a mixture of elements/compounds

External Revision: Chemistry (2 decks)

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