Qualitative analysis Flashcards

1
Q

What reagents are used to identify cations?

A
  • sodium hydroxide
  • aq ammonia
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2
Q

What is the effect of aqueous sodium hydroxide on calcium?

A
  • white ppt
  • insoluble in excess
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3
Q

What is the effect of aqueous ammonia on calcium?

A
  • no ppt
  • or very slight white ppt
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4
Q

What is the effect of aqueous sodium hydroxide on zinc?

A
  • white ppt
  • soluble in excess (gives colourless solution)
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5
Q

What is the effect of aqueous ammonia on zinc?

A
  • white ppt
  • soluble in excess (gives a colourless solution)
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6
Q

What is the effect of aqueous sodium hydroxide on aluminium?

A
  • white ppt
  • soluble in excess (gives colourless solution)
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7
Q

What is the effect of aqueous ammonia on aluminium?

A
  • white ppt
  • insoluble in excess
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8
Q

What is the effect of aqueous sodium hydroxide on lead?

A
  • white ppt
  • soluble in excess (gives colourless solution)
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9
Q

What is the effect of aqueous ammonia on lead?

A
  • white ppt
  • insoluble in excess
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10
Q

What is the effect of aqueous sodium hydroxide on copper (ll)?

A
  • light blue ppt
  • insoluble in excess
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11
Q

What is the effect of aqueous ammonia on copper (ll)?

A
  • light blue ppt
  • soluble in excess (gives a dark blue solution)
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12
Q

What is the effect of aqueous sodium hydroxide on iron (ll)?

A
  • green ppt
  • insoluble in excess
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13
Q

What is the effect of aqueous ammonia on iron (ll)?

A
  • green ppt
  • insoluble in excess
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14
Q

What is the effect of aqueous sodium hydroxide on iron (lll)?

A
  • red-brown ppt
  • insoluble in excess
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15
Q

What is the effect of aqueous ammonia on iron (lll)?

A
  • red-brown ppt
  • insoluble in excess
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16
Q

What is the effect of aqueous sodium hydroxide on ammonium?

A
  • ammonia produced upon warming
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17
Q

How does one differentiate between lead and aluminum ions?

A
  • add potassium iodide
  • in lead ion is present, bright yellow ppt of lead (ll) iodide will be observed
  • if aluminium is present, no visible change occurs
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18
Q

What is another way to differentiate between lead and aluminium ions other than adding potassium iodide?

A
  • add dilute HCl
  • if lead ion is present, a white ppt or PbCl2 will be observed
  • if aluminium ion is present, no visible change occurs
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19
Q

How does one identify a carbonate ion?

A
  • add dilute acid
  • if carbonate ion is present, effervescence will be observed
  • gas forms white ppt in limewater
  • carbon dioxide is produced
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20
Q

How does one identify a chloride ion?

A
  • acidify with dilute nitric acid
  • then add aq silver nitrate
  • if chloride ion is present, a white ppt is formed (silver chloride)
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21
Q

How does one identify an iodide ion? (1 of 2 ways)

A
  • acidify with dilute nitric acid
  • add aq silver nitrate
  • if iodide ion is present, a yellow ppt is formed
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22
Q

How does one identify an iodide ion (2 of 2 ways)

A
  • acidify with dilute nitric acid
  • add aq lead (ll) nitrate
  • if iodide ion is present,
    a bright yellow ppt is formed
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23
Q

How does one identify a nitrate ion?

A
  • add aq sodium hydroxide
  • then aluminium foil
  • warm
  • if nitrate ion is present, effervescence is observed
  • moist red litmus turns blue (ammonia produced)
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24
Q

How does one identify a sulfate ion?

A
  • acidify with dilute nitric acid
  • add aq barium nitrate
  • if sulfate ion is present, white ppt is formed
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25
Q

How does one test for ammonia?

A
  • place a damp piece of red litmus paper near the mouth of the test tube containing the gas
  • ammonia gas turns damp red litmus paper blue
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26
Q

How does one describe ammonia?

A
  • colourless
  • pungent gas
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27
Q

How does one test for carbon dioxide?

A
  • bubble the gas into lime water
  • carbon dioxide gas forms a white ppt of CaCO3 with limewater
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28
Q

How does one describe carbon dioxide?

A
  • colourless
  • odorless gas
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29
Q

How does one test for chlorine gas?

A
  • place a damp piece of blue litmus near the mouth of the test tube containing the gas
  • chlorine gas turns damp blue litmus paper red
  • it then bleaches damp litmus paper
30
Q

How does one describe chlorine gas?

A
  • greenish-yellow
  • pungent gas
31
Q

How does one test for oxygen?

A
  • insert a glowing splint into the mouth of the test tube containing the gas
  • oxygen gas relights a glowing splint
32
Q

how does one describe oxygen?

A
  • colourless
  • odorless gas
33
Q

How does one test for water vapour?

A
  • place cobalt (ll) chloride paper near the mouth of the test tube containing the vapour
  • if vapour turns blue cobalt (ll) chloride paper pink, water vapour is present
34
Q

How does one test for liquid water?

A
  • the vapour must be cooled and condensed into liquid
  • add a few drops of liquid to anhydrous copper (ll) sulfate
  • if the white anhydrous copper (ll) sulfate turns blue, water is present
35
Q

What is decomposition?

A
  • when a substance breaks down into simpler substances
36
Q

What does ammonium chloride form when decomposed?

A
  • ammonia gas
  • hydrogen chloride gas
37
Q

Can ammonia gas and hydrogen chloride gas recombine to form ammonium chloride?

A
  • yes
  • it is a reversible reaction
38
Q

What happens to hydrated salts when heated gently?

A
  • they lose water of crystallization
  • become anhydrous salts
  • water of crystallization appears as colourless droplets of liquid on the upper part of test tube
39
Q

What do some carbonates give when decomposed?

A
  • metal oxide
  • carbon dioxide
40
Q

What is zinc oxide when hot and cold?

A
  • yellow solid when hot
  • white solid when cold
41
Q

What are the colours of some common substances?

A
  • K, Na, Ca, Zn, Fe: silvery (polished) / grey (powder)
  • Cu: reddish brown or brown
42
Q

What colour are K2O, Na2O and CaO?

A
  • white
43
Q

What colour is ZnO?

A
  • yellow when hot
  • white when cold
44
Q

What colour is FeO (iron(ll)) oxide?

A
  • black
45
Q

What colour is Fe2O3?

A
  • reddish brown
46
Q

What colour is CuO (copper (ll) oxide)?

A
  • black solid
47
Q

What colour is Cu2O (copper (ll) oxide) ?

A
  • reddish brown solid
48
Q

What colour is CuCO3 (copper (ll) carbonate)?

A
  • green solid
49
Q

What colour is CuSO4 (copper (ll) sulfate)?

A
  • blue solid
50
Q

What colour are KOH and NaOH?

A
  • colourless
  • soluble in water
51
Q

Is Ca(OH)2 soluble in water?

A
  • slightly
52
Q

What colour is Zn(OH)2?

A
  • white
  • insoluble in water
53
Q

What colour is Fe(OH)2?

A
  • green/dirty green
  • insoluble in water
54
Q

What colour is Fe(OH)3?

A
  • reddish brown ppt
  • insoluble in water
55
Q

What colour is Cu(OH)2?

A
  • blue ppt
  • insoluble in water
56
Q

What colour are the salt solutions of K, Na, Ca and Zn?

A
  • colourless
57
Q

What colour is the salt solution of Fe (iron(ll))?

A
  • green
58
Q

What colour is the salt solution of Fe2 (iron(lll))?

A
  • yellowish brown (lower conc.)
  • reddish brown (higher conc.)
59
Q

What colour is Cu (copper (ll)) salt solution?

A
  • usually blue
60
Q

What colour is CuCl2 (copper(ll) chloride) solution?

A
  • bluish green
  • green
61
Q

What colour is carbon solid?

A
  • black
62
Q

What colour is fluorine gas?

A
  • pale yellow (r.t.p)
63
Q

What colour is bromine?

A
  • reddish brown liquid (r.t.p)
  • aq bromine and bromine gas are also reddish brown
64
Q

What colour is iodine?

A
  • black solid at r.t.p
  • vapour is violet
  • solution is yellowish-brown at lower conc. and reddish brown at higher conc.
65
Q

What colour is nitrogen dioxide gas?

A
  • reddish brown gas (r.t.p)
66
Q

What colour is nitrogen monoxide gas?

A
  • colourless (r.t.p)
  • neutral gas
67
Q

What colour is carbon monoxide gas?

A
  • colourless (r.t.p)
  • neutral gas
68
Q

What colour is manganese(IV) oxide?

A
  • black solid
69
Q

What colour is potassium dichromate(VI)?

A
  • orange solution
  • green when reduced
70
Q

What colour is universal indicator at different pH?

A
  • red at pH 1
  • green at pH 7
  • violet/purple at pH 14
71
Q

What colour is methyl orange at different pH?

A
  • red/orange at pH<4
  • yellow at pH>4