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Chemistry > C8 - Chemical Analysis > Flashcards

C8 - Chemical Analysis Flashcards

1
Q

what is a pure substance

A

a single element or compound not mixed with any other substance

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2
Q

what can be used to distinguish pure substances from mixtures

A

melting and boiling point data

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3
Q

what is a formulation

A

a mixture that has been designed as a useful product

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4
Q

how are formulations made

A

mixing the components in carefully measured quantities to ensure the product has the required properties

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5
Q

give examples of formulations

A

fuels
cleaning agents
paints
medicines
alloys
fertilisers
food

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6
Q

formula to calculate rF value

A

distance moved by substance/ distance moved by solvent

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7
Q

what may affect the rF value

A

the solvent

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7
Q

what is the test for hydrogen

A

using a burning splint held at the open end of a test tube of gas. hydrogen makes a pop sound and burns

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7
Q

how can a chromotogram be used to identify substances by comparing them with known substances

A

the number of spots they produce and the colour
how far the spots have moved up the paper or have the same Rf value

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8
Q

oxygen test

A

using a glowing splint inserted into a test tube of the gas. the splint relights in oxygen

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9
Q

carbon dioxide test

A

using an aqueous solution calcium hydroxide. carbon dioxide when shakened or bubbled through will turn the limewater milky

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10
Q

chlorine test

A

if damp litmus paper is put onto chlorine gas it is bleached

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11
Q

what can flame tests be used to identify

A

some metal ions

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12
Q

what colour do lithium compounds turn in the flame test

A

crimson flame

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13
Q

what colour do sodium compounds turn in the flame test

A

yellow flame

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14
Q

what colour do potassium compounds turn in the flame test

A

lilac flame

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15
Q

what colour do calcium compounds turn in the flame test

A

an orange-red flame

16
Q

what colour do copper compounds turn in the flame test

A

green flame

17
Q

what can be done if a sample contains a mixture of ions

A

some flame colours can be masked

18
Q

what can sodium hydroxide solution be used to identify

A

some metal ions

19
Q

which ions form white precipitates when added to sodium hydroxide

A

aluminium (but then redissolves in excess NaOH to form a colourless solution), calcium and magnesium ions

20
Q

what ions form coloured precipitates when added to sodium hydroxide

A

copper ii, iron ii, iron iii

21
Q

what colour does copper ii form when added to sodium hydroxide

A

blue precipitate

22
Q

what colour do iron ii ions form when added to sodium hydroxide

A

green precipitate

23
Q

what colour do iron iii ions form when added to sodium hydroxide

A

brown precipitate

24
Q

balanced equation to represent calcium reacting with insoluble hydroxide

A

Ca2+ + 2OH- ——> Ca(OH)2

25
Q

balanced equation to represent copper ii reacting with insoluble hydroxides

A

Cu2+ + 2OH- —-> 20

26
Q

balanced equation to represent iron ii reacting with insoluble hydroxides

A

Fe2+ + 2OH- —> Fe(OH)2

27
Q

balanced equation to represent iron iii reacting with insoluble hydroxides

A

Fe3+ + 3OH- ——> Fe(OH)3

28
Q

balanced equation to represent alumminium reacting with insoluble hydroxides

A

Al3+ + 3OH- —> Al(OH)3

29
Q

balanced equation to represent magnesium reacting with insoluble hydroxides

A

Mg2+ + 2OH- —> Mg(OH)2

30
Q

what do carbonates to react with to form carbon dioxide gas

A

dilute acids

31
Q

what can CO2 be identified with

A

limewater

32
Q

what do halide ions produce and when

A

precipitates with silver nitrate when there is dilute nitirc acid

33
Q

what colour precipitate is silver chloride

A

white

34
Q

what colour precipitate is silver bromide

A

cream

35
Q

what colour is silver iodide

A

yellow

36
Q

what do sulfate ions produce

A

white precipitate with barium chloride solution in the presence of hydrochloric acid

37
Q

what can be detected using instrumental methods

A

elements and compounds

38
Q

benefits of instrumental methods

A

accurate
sensitive
rapid
can be used to identify ions in mixtures

39
Q

how does flame emission spectroscopy work

A

the sample is put into a flame and the light given out is passed through a spectroscope. the output is a line spectrum that can be analysed to identify the metal ions in the solution and measure their concentrations

Chemistry (5 decks)

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