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GCSE Chemistry > Chemical Analysis (Paper 2) > Flashcards

Chemical Analysis (Paper 2) Flashcards

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1
Q

In paper chromatography, the solvent used is known as the what phase

A

Mobile

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2
Q

Substance that limewater tests for

A

Carbon dioxide

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3
Q

Which gas would you test for with a glowing splint

A

Oxygen

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4
Q

Formulation meaning

A

A mixture that has been designed as a useful product

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5
Q

Name for mixture that has been designed as a useful product

A

Formulation

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6
Q

What is a pure substance

A

A substance that is made up of only one type of element or compound

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7
Q

Name for type of substance that is made up of only one type of element or compound

A

Pure substance

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8
Q

How to test for carbon dioxide

A

Bubble through limewater

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9
Q

How to test for oxygen

A

Put a glowing splint inside the tube

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10
Q

How to test for hydrogen

A

Put a lighted splint inside the tube

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11
Q

Glowing splint meaning

A

A splint that has been lit and burnt for a few seconds then blown out (can be used to test for oxygen when put inside the tube)

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12
Q

Result for carbon dioxide test

A

Turns limewater cloudy

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13
Q

What happens to the limewater when carbon dioxide is present

A

Turns cloudy

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14
Q

Result for when oxygen is present

A

Relights a glowing splint

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15
Q

Result for when hydrogen gas is present

A

Makes a squeaky pop noise

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16
Q

Carbon dioxide test and result

A

Bubble through limewater
Limewater turns cloudy

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17
Q

Oxygen test and result

A

Put a glowing splint (one that has been burnt then blown out) inside the tube
Re- lights the glowing splint

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18
Q

Hydrogen test and result

A

Put a lighted splint inside the tube
Makes a squeaky pop noise

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19
Q

Only what type of substances melt and boil at specific temperatures

A

Pure substances

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20
Q

What temperature does water boil at

A

100 degrees Celsius

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21
Q

True or false, impure substances (e.g sodium chloride mixed with water) have fixed melting and boiling points

A

False,
Only pure substances like the pure water on its own or pure sodium chloride on its own have fixed melting and boiling points

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22
Q

True or false, formulations have been designed to have precise amounts of differnt components and therefore have a specific function

A

True
(Hence the name- they have a specific formula)

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23
Q

True or false, in formulations each different component is always included in the same proportion

A

True
(Each component may contribute to a different property to help with the overall function e.g paint/ medicine)

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24
Q

Chemical analysis (also called analytical chemistry) is about what

A

The instruments and methods we use to separate, identify and quantify different substances

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25
Q

True or false, a pure substance can be both an element or a compound

A

True
As long as it doesn’t have anything mixed into it but is made of just that single thing

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26
Q

If a substance melts over a range of temperatures is it a pure substance

A

No, it’s impure
Pure substances always melt at the same specific melting point

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27
Q

Is measuring a substance’s boiling point a chemical or physical test

A

Physical

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28
Q

True or false, there are lots of different types of chromatography, not just paper

A

True
E.g gas chromatography, but the only one we need to know about is paper chromatography
(Chromatography is a way of separating different components of a mixture)

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29
Q

Name for line that you draw at base of sheet with pencil in paper chromatography

A

Baseline

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30
Q

First step in paper chromatography

A

Take filter paper and draw horizontal line (baseline) with pencil near the bottom

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31
Q

How much solvent (e.g water/ ethanol) should you add to the beaker for paper chromatography

A

Shallow amount

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32
Q

Examples of 2 solvents to use in beaker for paper chromatography

A

Water/ ethanol

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33
Q

Stages for paper chromatography

A

1) take filter paper and draw horizontal line in pencil near the bottom (baseline)
2) add a dot of your sample e.g ink to the middle of the pencil line
3) place paper in beaker with shallow amount of solvent (e.g water) ensuring that the pencil line and ink aren’t submerged
4) place lid on top of beaker to stop solvent from evaporating
5) wait for solvent to seep up paper- the different dyes in the ink will dissolve in the solvent and move up the paper with it
6) different dyes move up paper at different rates (are separated)
7) once solvent has neatly reached top of paper, take paper out of beaker and leave to dry

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34
Q

Why should a lid be placed on the beaker in paper chromatography

A

Stop the solvent from evaporating

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35
Q

True or false, the baseline containing the ink sample in paper chromatography should be submerged in the solvent

A

False
It needs to be above the solvent which is why you only add a shallow amount to the beaker

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36
Q

2 types of phases in paper chromatography

A

Mobile phase
Stationary phase

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37
Q

Mobile phase meaning in paper chromatography

A

The solvent
(When the molecules in the sample e.g ink can move)

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38
Q

Stationery phase meaning in paper chromatography

A

The paper
Substance/ material that the molecules from the sample (e.g ink) can’t move in

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39
Q

What phase is the paper in paper chromatography

A

Stationery phase
As the molecules can’t move

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40
Q

In paper chromatography what stage is the paper and what stage is the solvent

A

Paper= stationery phase (molecules can’t move)
Solvent= mobile phase (molecules can move)

41
Q

In paper chromatography do the more soluble components move further up the paper or not

A

Yes, further as they spend more time in the mobile phase (solvent) so moving up the paper

42
Q

In paper chromatography do less soluble components move further up the paper or not

A

No, they spend more time in the stationery phase so staying still on the paper instead of moving up the paper in the solvent

43
Q

How to calculate Rf value (ratio of how far component moves compared to solvent)

A

Distance travelled by substance/ distance travelled by solvent

44
Q

2 things that must be taken into account when looking at Rf value

A

Solvent used
Type of paper used
(As these may alter the mobile and stationery phase and therefore Rf value, even if you’re using the same pure substance e.g pure water both times)

45
Q

Why should we use pencil for the baseline not pen

A

Pen would dissolve in the solvent so move up the paper

46
Q

How to test for chlorine

A

Take damp blue litmus paper and place in test tube that’s suspected to have chlorine gas in

47
Q

Result for chlorine test

A

Damp blue litmus paper turn white

48
Q

Chlorine test and result

A

Take damp blue pice of litmus paper and place in test tube
If chlorine is present litmus paper will turn white (is bleached)
(It may temporarily turn red before turning white due to hydrochloric acid being formed)
(Wear mask as chlorine gas is poisonous)

49
Q

Another name for limewater

A

Calcium hydroxide

50
Q

Another name for calcium hydroxide

A

Limewater

51
Q

2 safety precautions for when testing for chlorine gas

A

Wear gas mask
Do experiment in a fume cupboard

52
Q

What is the first way we test for positive ions

A

Flame test

53
Q

Are anions positive or negative ions

A

Negative

54
Q

Are cations positive or negative ions

A

Positive

55
Q

Which out of anions and cations are positive or negative ions

A

Anions= negative ions
Cations= positive ions

56
Q

3 types of negative ions we test for

A

Halide
Sulfate
Carbonate

57
Q

How to test for carbonate and why

A

Hydrochloric acid (add to sample with suspected carbonate in)
When a carbonate + acid react together it produces carbon dioxide, a salt and water

Bubble gas through limewater
If limewater turns cloudy then carbon dioxide is present meaning that it must have been carbonate as carbonate produces the carbon dioxide

58
Q

2 steps for testing for carbonates

A

1) add hydrochloric acid to test tube
2) bubble gas that’s produced through limewater

Positive result= limewater goes cloudy due to gas being CO2 which is released from the carbonate reacting with the acid

59
Q

2 steps for testing for sulphates

A

1) Add hydrochloric acid to test tube
2) Add barium chloride solution to same test tube

Positive result= white precipitate formed

60
Q

3 halide ions we test for

A

Iodide
Chloride
Bromide

61
Q

How to test for halide ions (bromide, iodide and chloride)

A

Add dilute nitric acid to remove any impurities (carbonate and sulphite ions) that could form a precipitate and give a false positive result

Add silver nitrate- halide ions react with silver to form different colour precipitates
Iodide= yellow
Chloride= white
Bromide= cream

62
Q

What colour precipitate does (silver) iodide form

A

Yellow

63
Q

What colour precipitate does (silver) bromide form

A

Cream

64
Q

What colour precipitate does (silver) chloride form

A

White

65
Q

What colour precipitates do chloride, bromide and iodide ions form

A

Chloride= white
Bromide= cream
Iodide= yellow

66
Q

When testing for halide ions what do the halide ions react with to form the differnt coloured precipitates

A

Silver in the silver nitrate
(Forms silver iodide/ silver bromide/ silver chloride)

67
Q

When testing for sulphate ions what do the sulphate ions react with to form the white precipitate

A

Barium ions in the barium chloride

68
Q

Along with silver nitrate (for halide ions) and barium chloride (for sulphate ions) why is a dilute acid also needed

A

Remove any impurities like carbonate ions an sulfate ions which could also react with the barium/ silver to form a precipitate and give off a false positive result

69
Q

2 ways to collect gas when testing for carbonate

A

Attach top of test tube to gas syringe
Place upside down measuring cylinder over test tube to trap the gas

70
Q

2 ways to test for positive ions

A

Flame test
Sodium hydroxide

71
Q

What colour flame does lithium go

A

Crimson
(Chile- Li at end for lithium and Chile is crimson coloured)

72
Q

What colour flame does Sodium go

A

Yellow
(Banana- has Na in it for sodium and banana is yellow)

73
Q

What colour flame does potassium go

A

Lilac- plum has p in it for potassium and plum is lilac coloured

74
Q

What colour flame does calcium go

A

Orange/ red
Carrot- has Ca in it for calcium and carrot is orange

75
Q

What colour flame does copper go

A

Green
Cucumber- has Cu in it for copper and is green

76
Q

What do we do to test for positive metal ions if there was no positive result from the flame test (or if the flame was red which means it could be either lithium or calcium)

A

Add a few drops of sodium hydroxide

77
Q

What colour precipitate does magnesium form

A

White

78
Q

What colour precipitate does calcium form

A

White

79
Q

What colour precipitate does copper form

A

Blue

80
Q

What colour precipitate does iron 2 form

A

Green

81
Q

What colour precipitate does iron 3 form

A

Brown

82
Q

What colour precipitate does aluminium form

A

White (dissolves in excess)

83
Q

Which 3 metals form white precipitates

A

Magnesium
Calcium
Aluminium (dissolves in excess)

84
Q

Which metal forms a white precipitate that dissolves in excess

A

Aluminium

85
Q

2 metals that form white precipitates and don’t dissolve in excess

A

Calcium
Magnesium

86
Q

Metal that forms blue precipitate

A

Copper

87
Q

Metal that forms green precipitate

A

Iron 2

88
Q

Metal that forms brown precipitate

A

Iron 3

89
Q

Metal that gives crimson flame

A

Lithium

90
Q

Metal that gives yellow flame

A

Sodium

91
Q

Metal that gives lilac flame

A

Potassium

92
Q

Metal that gives orange/ red flame

A

Calcium

93
Q

Metal that gives green flame

A

Copper

94
Q

Negative ion used to test for with barium chloride and hydrochloric acid

A

Sulphate ions

95
Q

Negative ion used to test for with hydrochloric acid (and then limewater)

A

Carbonate

96
Q

Negative ion used to test for with nitric acid and silver nitrate

A

Halide ions (bromide, chloride and iodide)

97
Q

Chemical analysis is about the instruments and methods used to…..

A

Separate, identify and quantify different chemicals

98
Q

A pure substance is a substance made up of only one type of element or…

A

Compound

GCSE Chemistry (18 decks)

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