Identifying compounds Flashcards

1
Q

What is the test for carbonates and hydrocarbonates?

A

Add acid to the carbonate (HCl)
Connect to test tube with limewater
If present the CO2 produced will turn limewater cloudy

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2
Q

What is the result of the flame-test of Sodium?

A

Yellow-orange flame

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3
Q

What is the result of the flame-test of Potassium?

A

Lilac flame

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4
Q

What is the result of the flame-test of Calcium?

A

Brick red flame

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5
Q

What is the result of the flame-test of Lithium?

A

Crimson red flame

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6
Q

What is the result of the flame-test of Rubidium?

A

Reddish-violet

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7
Q

What is the result of the flame-test of Caesium?

A

Blue-violet

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8
Q

What is the result of the flame-test of Strontium?

A

Red

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9
Q

What is the result of the flame-test of Barium?

A

Pale green

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10
Q

What is the result of the flame-test of Copper?

A

Blue-green

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11
Q

How do you perform a flame test?

A

Clean a nichrome wire in conc hydrochloric acid and put into Bunsen flame
Dip into small amount of solid and put into the Bunsen flame

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12
Q

How is the test for halide ions done?

A

Dissolve solid in pure water
Acidified using dilute nitric acid
Silver nitrate (aqueous) added

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13
Q

Why is dilute nitric acid when testing for halide ions?

A

Reacts with and removes other ions which may give a precipitate with silver nitrate

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14
Q

What coloured precipitate forms if F- ions are present in a compound?

A

No precipitate

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15
Q

What coloured precipitate forms if Cl- ions are present in a compound?

A

White precipitate

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16
Q

What coloured precipitate forms if Br- ions are present in a compound?

A

Cream precipitate

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17
Q

What coloured precipitate forms if I- ions are present in a compound?

A

Yellow precipitate

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18
Q

How does AgCl react with ammonia solution?

A

Dissolves in dilute ammonia solution

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19
Q

How does AgBr react with ammonia solution?

A

Precipitate doesn’t dissolve in dilute ammonia solution

Precipitate dissolves in conc ammonia solution giving colourless solution

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20
Q

How does AgI react with ammonia solution?

A

Precipitate is insoluble in all concentrations of ammonia

21
Q

Which colour is fluorine?

A

Pale yellow

22
Q

Which colour is chlorine gas?

A

Green

23
Q

Which colour is bromine liquid?

A

Red-brown

24
Q

Which colour is iodine solid?

A

Grey solid

25
Q

What colour is chlorine in water and hexane?

A

Water: Virtually colourless
Hexane: Virtually colourless

26
Q

What colour is bromine in water and hexane?

A

Water: Yellow/orange
Hexane: Orange/red

27
Q

What colour is iodine in water and hexane?

A

Water: Brown
Hexane: Pink/violet

28
Q

How do you test for sulphate ions?

A

Add dilute HCl
Add Barium chloride solution
Positive result gives a white precipitate

29
Q

Why is hydrochloric acid added in the test for sulphate ions?

A

Removes any traces of carbonate ions before the test

30
Q

What is the test for ammonium compounds?

A

Add some NaOH
Gently heat
Put damp litmus paper over test tube
Positive test turns red litmus paper blue

31
Q

Where should the test for ammonia compounds be done?

A

Fume cupboard as produces an irritant gas

32
Q

Why does the litmus paper have to be damp when testing for ammonia ions?

A

Ammonia gas can dissolve and make the colour change

33
Q

What is the test for metal ions with NaOH?

A

Add sodium hydroxide to the metal ion solution

34
Q

What is the result for copper (II) sulphate when NaOH added?

A

Light blue precipitate forms

35
Q

What is the result for iron (II) when NaOH added?

A

Green precipitate

Darkens on standing as it forms iron (III) hydroxide

36
Q

What is the result for iron (III) when NaOH added?

A

Orange precipitate

Darkens on standing

37
Q

What is the result when cobalt (II) when NaOH is added?

A

Blue precipitate

Turns brown on standing

38
Q

What is the colour of copper(II) solution?

A

Pale blue solution

39
Q

What is the colour of iron(II) solution?

A

Pale green solution

40
Q

Why does iron(II) precipitate darken on standing?

A
Oxidised by water and oxygen in air
Forms iron(II) hydroxide
41
Q

What is the colour of iron(III) solution?

A

Yellow solution

42
Q

What is the colour of cobalt(II) solution?

A

Pale pink solution

43
Q

What is the colour of cobalt nitrate?

A

Yellow-brown solution

44
Q

What is the colour of Chromium nitrate?

A

Purple

45
Q

What is the colour of Copper chloride?

A

Yellow solution

46
Q

What is the colour of cobalt chloride?

A

Blue

47
Q

How do you test for SO2?

A

Turns potassium dichromate paper orange to green

48
Q

How do you test for H2S?

A

Turns lead ethanoate paper from white to black

49
Q

How could you tell the difference between an aldehyde and ketone using 2,4-DNP?

A
React both with 2,4-DNP
Take yellow precipitate and recrystallise
Make crystal dry
Determine melting point
Compare to data booklet value