Qualitative Analysis

Question 1

3 types of identification

Answer 1

1. Evolution of gas
2. Formation of precipitate
3. Visible colour change

Question 2

What metals have coloured compounds?

Answer 2

Transition metals

Question 3

What groups’ metals form white salts and colourless solutions

Answer 3

Group I, II, II metals

Question 4

Colour of hydrated copper sulfate
Colour of anhydrous copper sulfate

Answer 4

Blue, White

Question 5

Colours of compounds
1. Colourless
2. White
3. Black
4. Grey
5. Dark green
6. Light green
7. Blue/bluish green
8. Yellow/brown
9. Pale pink
10. Purple

Answer 5

Colourless: Group I, II , III metals

White: Salts of Group I, II, III, Amphoteric metals, Ammonium salts

Black: CuO, CuS, CoO, FeO, FeS, PbS, MnO2, I2 crystals

Grey: Metals in power form

Dark green: Chromium salts

Light green: Iron II salts

Blue/Bluish green: hydrated Cu2+ salts

Yellow/Brown: Fe3+, PbI2, AgI solutions

Pale pink: Manganese salts

Purple: KMnO4

Question 6

What solutions are used to test for cations

Answer 6

Aqueous sodium hydroxide
Aqueous ammonia

Question 7

What is produced when an amphoteric metal reacts with an acid or a base

Answer 7

Complex soluble salt to give colourless solutions

Question 8

Test for cations and results

Answer 8

Check notes

Question 9

Test for anions and results

Answer 9

Check notes

Question 10

Test for gases and results
(carbon dioxide, sulfur dioxide, oxygen, hydrogen, chlorine, ammonia)

Answer 10

Check notes

Question 11

If a gas is evolved after the the addition of HNO3, what is the compound

Answer 11

Either a reactive metal or a carbonate

Question 12

How does litmus paper work

Answer 12

Litmus paper is moist to dissolve the gas and allow it to dissociate to form H+/ OH- ions

Question 13

Definition of thermal decomposition

Answer 13

Chemical reaction in which a single compound breaks down into 2 or more simpler compounds/elements upon heating

Question 14

Decomposition of carbonates give ___

Answer 14

_____ oxide + CO2

Question 15

Decomposition of nitrate give _____

Answer 15

_____ oxide + nitrogen dioxide + oxygen

Question 16

Decomposition of sulfites give _____

Answer 16

_____ oxide + sulfur dioxide gas

Question 17

Sulfides Sulfites Sulfates
Nitrides Nitrites Nitrates

Answer 17

S2-, SO3 2-, SO4 2-
N3-, NO2 - , NO3 -

Question 18

Hydrated salts definition

Answer 18

ioninc compounds that contain water within their crystal structure known as water of crytallisation
→ upon heating, water of crystlisation will be expelled as water vapour → leaving anhydrous salt behin

Question 19

Thermal stability & Reactivity

Answer 19

The more reactive the metal, the more thermally stable the metal compound

Question 20

Heat on oxide

Answer 20

All stable except
Gold and silver decompose to metal + oxygen

Question 21

Heat on hydroxide

Answer 21

Sodium and Potassium stable
Rest decompose to metal oxide + water
(For gold and silver, further decompose to metal + oxygen)

Question 22

Heat on carbonate

Answer 22

Sodium and Potassium stable
Rest decompose to metal oxide + CO2
(For gold and silver, further decompose to metal + oxygen)

Question 23

Heating of carbonates (initial and final colour + gas evolved)

Answer 23

Check notes

Question 24

Solubility table

Answer 24

Check Y3 Notes