Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Science revision > Separating and purifying substances > Flashcards

Separating and purifying substances Flashcards

You may prefer our related Brainscape-certified flashcards:
Biology 101 flashcards
1
Q

What are the three states of matter?

A

Solid, liquid, gas

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What is the particle model?

A

It explains state changes in a substance in terms of the arrangement, movement and energy stored in its particles

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

what is the arrangement of particles in a gas?

A

Random and far apart

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

what is the arrangement of particles in a liquid?

A

random and close together

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

what is the arrangement of particles in a solid?

A

regular and close togther

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

what is the movement of particles in gas?

A

fast in all directions

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

what is the movement of particles in a liquid?

A

particles move around each other

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

what is the movement of a solid?

A

vibrate about fixed positions

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

are state changes physical or chemical, why?

A

physical because they can reversed and the chemical properties of the substance do not change only their arrangement, movement and amount of energy

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

what is deposition?

A

the direct change from gas to solid

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

what is sublimation?

A

the direct change from solid to gas

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

what is the change from gas to liquid called?

A

condensing

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

what is the change from liquid to solid called?

A

freezing

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

what is the change from solid to liquid callled?

A

melting

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

what is the change from liquid to gas called?

A

evaporation and boiling

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

why does the temperature stay the same at the melting and boiling point?

A

the substance is still being heated but the added energy is making the particles break away from their fixed arrangement

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

what would the state be below the melting point?

A

solid

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

what would the state be between the melting and boiling point?

A

liquid

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

what would the state be above the boiling point?

A

gas

20
Q

what is the make-up of a pure substance?

A

cannot be changed

is the same in all parts of a piece of the substance

21
Q

why can’t we separate a pure substance into other substances?

A

it has the same fixed composition in all its parts.

22
Q

what is a mixture?

A

a mixture contains elements and/or compounds that are not chemically joined together

23
Q

True or False?
A mixture does not have a fixed composition, so you can use physical processes to separate mixtures into different substances

A

True

24
Q

What happens when a solid melts?

A

Its particles gain enough energy to overcome the weak forces of attraction between them and move away from each other at the melting point.

25
Q

True or False?

Not all of a pure substance will melt at the same temperature

A

False

All of a pure substance will ,elt at the same temperature until all of the substance has changed state.

26
Q

Do mixtures have a fixed, sharp melting point?

A

No

27
Q

What are filters used for?

A

Filters can be used to separate some mixtures, to let smaller pieces or liquids through but trap bigger ones or insoluble substances.

28
Q

What is a solution?

A

A solution is a mixture made of solutes (dissolved substances) in a liquid called a solvent.

29
Q

What is crystallisation?

A

It is used to produce solid crystals from a solution. Separating solutes from a solution by heating the solution and evaporating the solvent to leave the solutes behind. When what’s left cools crystals form.

30
Q

What is the process for filtration?

A

1) Funnel is lined with filter paper
2) The solvent and solute(s) pass through to form the filtrate
3) Insoluble substances can’t pass so leave a residue

31
Q

What can chromatography be used for?

A

It can be used to find out which coloured compounds the mixture contains.

32
Q

What is the mobile phase?

A

The solvent

33
Q

What is the stationary phase?

A

The paper

34
Q

What happens during paper chromatography?

A

A solvent (e.g. water) moves along a strip of paper, it carries the mixture (e.g. ink) at different speeds, so they are separated.

35
Q

What is a chromatogram?

A

The paper with the separated components on it

36
Q

True or False?

More soluble compounds are carried up faster

A

True

37
Q

How do you calculate the Rf value?

A

Rf = distance moved by the spot / distance moved by the solvent

38
Q

What is distillation used for?

A

To make pure substances by separating it from the dissolved solids

39
Q

What happens during distillation, using the example of water

A

Mineral water evaporates, only the water turns to gas (vapour). The solid minerals which have much higher boiling points are left behind. The water vapour is pure, it is then condensed and turned back to liquid.

40
Q

What is the apparatus used in distillation called?

A

A still

41
Q

What can fractional distillation be used for?

A

To separate the different products of crude oil
To make alcoholic drinks such as whisky and vodka
To separate out the gases in the air, after the air has been cooled and turned into liquid at -200°C

42
Q

What is producing pure water from sea water called?

A

Desalination

43
Q

Why is simple distillation not usually suitable for producing large amounts of drinking water?

A

A lot of energy must be transferred to seawater

44
Q

What does chemical analysis involve?

A

It involves using chemical reactions or sensitive machines to identify and measure the substances in a sample.

45
Q

During chemical analysis why can’t the water contain dissolved salts?

A

Incorrect results will be obtained

46
Q

What does fresh water from sources like rivers, lakes and aquifers contain?

A

Objects such as leaves and twigs
Small insoluble particles such as grit and silt
Soluble substances including salts, pesticides and fertilisers
Bacteria and other microorganisms that may be harmful to health

47
Q

What steps are needed to deal with the impurities from fresh water?

A

Screening using a sieve
Sedimentation ( in which small particles are allowed to settle)
Filtration using tanks containing beds of sand and gravel
Chlorine is added to kill microorganisms in a process called chlorination

Science revision (3 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions