Observation

Inference

1. Substance is coloured

i) Blue

Copper salt

ii) Dark green

Chromium salt

iii) Green

Salts of Fe, Ni, Cu or Cr

iv) Light yellow or brown

Salts of Fe(ic)

v) Dark brown

PbO₂,Bi₂S₃

vi) Light pink

Salts of Mn

vii) Pink

Salts of Co

viii) Red

HgO, HgI₂,Pb₃O₄

ix) Orange red

Sb₂S₃

2. Substance is wet

CaCl₂,ZnCl₂,MgCl₂, MnCl₂, nitrites, nitrates

3. Substance is heavy

Salts of Pb, Hg and Ba

4. Substance is light

Carbonates of Bi, Mg, Al, Zn, Ca, Sr

Observation

Inference

1. Substance melts

Salts of alkali metals and salts having water crystallisation.

2. Substance decrepitates (craking noise)

NaCl, KI, Pb(NO₃)₂ and Ba(NO₃)₂

3. Substance swells (due to loss of water of crystallisation)

Alums, borates and phosphates

4. The substance sublimes and the colour of sublimate is

i) White

HgCl₂, Hg₂Cl₂,NH₄X, AlCl₃, As₂O₃, Sb₂O₃

ii) Yellow

As₂S₃ and HgI₂ (turns red when rubbed with glass rod).

iii) Blue black and violet vapours

Iodides

5. A residue (generally oxide) is left and its colour is

i) Yellow (hot) and white (cold)

ZnO

ii) Reddish brown (hot); yellow (cold)

PbO

iii) Black (hot); Red (cold)

HgO, Pb₃O₄

iv) Black (hot); Red brown (cold)

Fe₂O₃

6. Gas is evolved

(A) Colourless and odourless

i) O₂ - rekindles a glowing splinter

Alkali nitrates (2KNO₃ 2KNO₂ + O₂)

ii) CO₂ - turns lime water milky

Carbonates and oxalates (CaCO₃ CaO + CO₂)

iii) N₂

Ammonium nitrite (NH₄NO₂ N₂+ 2H₂O)

(B) Colourless gas with odour

i) NH₃- Turns red litmus blue and mercurous nitrate paper black

Ammonium salts (NH₄)₂SO₄ NH₄HSO₄ + NH₃

ii) SO₂ - Smell of burning sulphur, turns acidified K₂Cr₂O₇ paper green

Sulphites and thiosulphates
CaSO₃ CaO + SO₂

iii) HCl - Pungent smell, white fumes with ammonia

Hydrated chlorides CaCl₂.6H₂O Ca(OH)₂ + 4H₂O + 2HCl

iv) H₂S - smell of rotten eggs, turns lead acetate paper black

Sulphides
Na₂S + 2H₂O 2NaOH + H₂S

(C) Coloured gas

i) NO₂ - Brown, turns starch iodide paper blue

Nitrites and nitrates of heavy metals
2Cu(NO₃) 2CuO + 4NO₂ + O₂

ii) Br₂ - Reddish brown

Bromides
2CdBr₂ + O₂ CdO + 2Br₂

(A) Turns starch paper yellow

(B) turns starch iodide paper blue

iii) I₂- Violet, turns starch paper blue

Iodides 2CdI₂ + O₂ 2CdO + 2I₂

iv) Cl₂ - Greenish yellow

Chlorides

(A) bleaches moist litmus paper

CuCl₂ + H₂O CuO + 2HCl
CuO + 2HCl Cu + H₂O + Cl₂

(B) bleaches indigo solution

(C) turns starch iodide paper blue