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IGCSE Chemistry > Chemical Analysis > Flashcards

Chemical Analysis Flashcards

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1
Q

What is the gas test for hydrogen?

A

A Burning Splint

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2
Q

What is the positive result for the hydrogen test?

A

The burning splint explodes with a pop

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3
Q

What is the gas test for oxygen?

A

A Glowing Splint

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4
Q

What is the positive result for the Oxygen test?

A

The glowing splint reignites

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5
Q

What is the gas test for Carbon Dioxide?

A

Limewater

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6
Q

What is the positive result for the Carbon Dioxide test?

A

Limewater turns cloudy.

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7
Q

What is the gas test for Chlorine?

A

Damp Blue Litmus

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8
Q

What is the positive result of the gas test for Chlorine?

A

The damp blue litmus turns red, then white.

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9
Q

What is the gas test for Ammonia (NH3)?

A

Damp Red Litmus

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10
Q

What is the positive result for the gas test for Ammonia

A

The damp red litmus turns blue

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11
Q

How does the burning splint tell us Hydrogen gas is made?

A

It makes hydrogen react with oxygen, which is highly EXOTHERMIC, and therefore creates the pop noise.

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12
Q

How does the Glowing Splint tell us Oxygen gas is made?

A

Oxygen is required for combustion, and the flame on the glowing splint is about to extinguish. If placed in oxygen, it will reignite. This tells us Oxygen gas is made.

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13
Q

How does limewater tell us Carbon Dioxide gas is made?

A

Limewater is Ca(OH)2. It reacts with Carbon Dioxide to make CaCO3, a white precipitate. Therefore the limewater turns cloudy.

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14
Q

How does the damp blue litmus tell us that Chlorine gas is made?

A

Chlorine reacts with water to make HCl. HCl reacts with indicator on the paper to go from blue (base) -> red (acid). If this happens Chlorine gas was made. Later, the Chloric acid will make the paper turn white.

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15
Q

How does the damp red litmus tell us that Ammonia (NH3) gas is made?

A

Ammonia is a base, and therefore it will react with the indicator on the paper, going from red (acid) -> blue (base). If this happens, Ammonia gas was made.

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16
Q

What is the basic method for a gas test?

A

Place each specific test inside a test tube producing an unknown gas, until one of them produces a positive result.

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17
Q

What color do Lithium compounds produce in the flame test?

A

Red

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18
Q

What color do Sodium compounds produce in the flame test?

A

Yellow/Orange

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19
Q

What color do Potassium compounds produce in the flame test?

A

Lilac

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20
Q

What color do Calcium compounds produce in the flame test?

A

Brick red

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21
Q

What color do Barium compounds produce in the flame test?

A

Light green or apple green

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22
Q

What color do Copper compounds produce in the flame test?

A

Blue/green

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23
Q

What is the basic method for the flame test?

A
  1. Clean needle with HCl until it doesn’t change the color of the flame
  2. Place needle in compound and then in fire
  3. Observe flame color
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24
Q

What result from the halide test tells us Chloride was present?

A

White precipitate

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25
Q

What result from the halide test tells us Bromide was present?

A

Cream precipitate

26
Q

What result from the halide test tells us Iodide was present?

A

Yellow Precipitate

27
Q

Which anion was present if the precipitate turns dark grey when exposed to Ultra-Violet light

A

Chloride

28
Q

What is the basic method for a Halide Test

A
  1. Add Nitric Acid to remove Hydroxide and Carbonate ions
  2. Add SilverNitrate and observe precipitate
29
Q

Why do we react SilverNitrate with the compound?

A

Because Silver Halides, which will be made if the unknown compound is soluble, are insoluble. Therefore it is a precipitation reaction, and we can identify which halide it is based on color of precipitate.

30
Q

Example: what is the Ionic equation for the reaction:
(X = unknown anion)
AgNO3 + NaX –> AgX + NaNO3

A

Ag+ + X- –> AgX

31
Q

What is the basic method to test for Ammonium (NH4+) Cations?

A
  1. Add NaOH and heat chemical
  2. If a gas is made, put damp red litmus in it
  3. Observe color of damp red litmus
32
Q

What is the positive result for the Ammonium (NH4+) test?

A

Damp red litmus turns blue.

33
Q

Why does the damp red litmus turn blue if Ammonium (NH4+) was present?

A

The reaction makes Ammonia (NH3). This is a base and. makes the indicator on the litmus go from red (acid) –> blue (base)

34
Q

What gas is made if a burning splint explodes with a pop?

A

Hydrogen

35
Q

What gas is made if a glowing splint reignites?

A

Oxygen

36
Q

What gas is made if limewater goes cloudy?

A

Carbon Dioxide

37
Q

What gas is made if damp blue litmus turns red then white?

A

Chlorine

38
Q

What gas is made if damp red litmus turns blue

A

Ammonia (NH3)

39
Q

What Cation is present if the flame turns red?

A

Lithium

40
Q

What Cation is present if the flame turns yellow?

A

Sodium

41
Q

What Cation is present if the flame turns lilac?

A

Potassium

42
Q

What Cation is present if the flame turns brick red?

A

Calcium

43
Q

What Cation is present if the flame turns light green?

A

Barium

44
Q

What Cation is present if the flame turns blue/green?

A

Copper

45
Q

What anion was present if the halide test turns white?

A

Chloride

46
Q

What anion was present if the halide test turns cream?

A

Bromide

47
Q

What anion was present if the halide test turns yellow?

A

Iodide.

48
Q

Which cation was present if damp red litmus paper turns blue?

A

Ammonium (NH4+)

49
Q

What is the basic method to test for nitrate?

A
  1. Add NaOH to the compound
  2. Add Al Powder and heat
  3. Place damp red litmus in gas
  4. Observe color of litmus paper
50
Q

What is the positive result for the nitrate test?

A

Damp red litmus turns blue

51
Q

Why does damp red litmus turn blue when exposed to nitrate compounds?

A

Nitrate compounds are bases. This means that the indicator on the litmus goes from red (acid) –> blue (base)

52
Q

What is the basic method for the NaOH/NH3 tests (on other compounds)?

A
  1. dissolve sample in water
  2. add drops of NaOH / NH3 and observe precipitate
  3. Add excess drops of NH3 / NaOH and observe precipitate
53
Q

Interpret these results for the NaOH and NH3 tests:
NaOH: colorless (aq)
Excess NaOH: colorless (aq)
NH3: colorless (aq)
Excess NH3: colorless (aq)

A

group 1 compound

54
Q

Interpret these results for the NaOH and NH3 tests:
NaOH: white (s)
Excess NaOH: white (s)
NH3: white (s)
Excess NH3: white (s)

A

group 2 compound

55
Q

Interpret these results for the NaOH and NH3 tests:
NaOH: green (s) –time-> orange (s)
Excess NaOH: green (s)
NH3: green (s)
Excess NH3: green (s)

A

Fe2+ compound

56
Q

Interpret these results for the NaOH and NH3 tests:
NaOH: orange/brown (s)
Excess NaOH: orange/brown (s)
NH3: orange/brown (s)
Excess NH3: orange/brown (s)

A

Fe3+ compound

57
Q

Interpret these results for the NaOH and NH3 tests:
NaOH: blue (s)
Excess NaOH: blue (aq). Redissolves
NH3: dark blue and white (s)
Excess NH3: dark blue (aq). Redissolves

A

Cu2+ compound

58
Q

Interpret these results for the NaOH and NH3 tests:
NaOH: green/grey (s)
Excess NaOH: green/grey (s)
NH3: green/grey (s)
Excess NH3: green/grey (s)

A

Cr3+ compound

59
Q

Interpret these results for the NaOH and NH3 tests:
NaOH: white (s)
Excess NaOH: colorless (aq)
NH3: white (s)
Excess NH3: colorless (aq)

A

Zn2+ compound

60
Q

Interpret these results for the NaOH and NH3 tests:
NaOH: faint white (s)
Excess NaOH: colorless (aq)
NH3: faint white (s)
Excess NH3: faint white (s)

A

Al3+ compound

IGCSE Chemistry (22 decks)

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