icse x action of heat on compounds

1. 1
1. OXIDES
Name of the compound
Formula
Original Colour Final Colour Residue
Gas evolved and test
Equation
1. Oxides of potassium, sodium, calcium, magnesium, aluminum, zinc, iron and copper do not decompose on heating.
2
Zinc Oxide
ZnO
White
Yellow when hot
White when cold
Residue turns white on
cooling
Does not decompose (only changes colour)
Eqn
: ZnO  ZnO
(White) (Yellow)
3
Lead Dioxide
PbO2
Chocolate brown Yellow
Yellow residue fuses with
test tube
Oxygen
Colourless, odourless neutral gas, rekindles a
glowing splinter
Eqn
: 2PbO2  2PbO + O2
4
Red Lead
Pb3O4
Red Yellow
Yellow residue fuses with
the test tube
Oxygen 
Colourless, odourless neutral gas, rekindles a
glowing splinter
Eqn
: 2Pb3O4  6PbO +O2
5
Mercuric Oxide
HgO
Red Silvery liquid
Silvery mirror on sides of
test tube
Oxygen 
Colourless, odourless neutral gas, rekindles a

2. 2
glowing splinter
Eqn
: 2HgO  2Hg + O2
6
Silver Oxide
Ag2O
Greyish black Silver
Silver residue at the
bottom of the test tube
Oxygen 
Colourless, odourless neutral gas, rekindles a
glowing splinter
Eqn
: 2Ag2O  4Ag + O2
GAS =  PRECIPITATE = 
2. CARBONATES
Name of the compound
Formula
Original Colour Final Colour Residue
Gas evolved test
Equation
1 Sodium and Potassium carbonate do not decompose on heating
2
Calcium Carbonate
CaCO3
White White
White residue of calcium
oxide obtained
Carbon dioxide 
Colourless, odourless, slightly acidic to litmus and
turns lime water milky
Eqn
: CaCO3  CaO + CO2
3
Magnesium Carbonate
MgCO3
White White
White residue of
magnesium oxide
obtained
Carbon dioxide 
Colourless, odourless, slightly acidic to litmus and
turns lime water milky
Eqn
: MgCO3  MgO + CO2

3. 3
4 Zinc Carbonate
ZnCO3 White
Yellow when hot white
when cold
Yellow residue of zinc
oxide obtained which
turns white on cooling
Carbon dioxide 
Colourless, odourless, slightly acidic to litmus and
turns lime water milky
Eqn
: ZnCO3  ZnO + CO2
5
Lead Carbonate
PbCO3
White Yellow
Yellow residue fuses with
the sides of the test tube
Carbon dioxide 
Colourless, odourless, slightly acidic to litmus and
turns lime water milky
Eqn
: PbCO3 PbO + CO2
6
Copper Carbonate
CuCO3
Light green Black
Black copper oxide
formed
Carbon dioxide 
Colourless, odourless, slightly acidic to litmus and
turns lime water milky
Eqn
: CuCO3  CuO + CO2
7
Ammonium carbonate
(NH4)2CO3
White No residue
Decomposes on exposure
to air and leaves no
residue
Carbon dioxide 
Colourless, odourless, slightly acidic to litmus
and turns lime water milky
Ammonia 
Pungent, smelling, basic gas turns red litmus

4. 4
blue and gives dense white fumes with a glass
rod of HCl acid
Water Vapour 
Neutral vapours turn Cobalt Chloride paper
blue to pink
Eqn
: (NH4)2CO3  2NH3 + H2O (vap) + CO2
3. BICARBONATES
Name of the compound
Formula
Original Colour Final Colour Residue
Gas evolved test
Equation
1
Sodium Bicarbonate
NaHCO3
White White
White solid sodium
carbonate
Carbon dioxide 
Colourless, odourless, slightly acidic to
litmus and turns lime water milky
Water Vapour
Neutral vapours turn Cobalt Chloride paper
blue to pink
Eqn
: 2NaHCO3  Na2CO3 + H2O+CO2
2
Potassium Bicarbonate
KHCO3
White White
White solid potassium
carbonate
Carbon dioxide 
Colourless, odourless, slightly acidic to litmus
and turns lime water milky
Water Vapour
Neutral vapours turn Cobalt Chloride paper

5. 5
blue to pink
Eqn
: 2KHCO3  K2CO3 + H2O+CO2
3
Calcium Bicarbonate
Ca(HCO3)2
White White
White Calcium carbonate
residue
Carbon dioxide 
Colourless, odourless, slightly acidic to litmus
and turns lime water milky
Water Vapour
Neutral vapours turn Cobalt Chloride paper
blue to pink
Eqn
: Ca(HCO3) 2 CaCO3 + H2O+CO2
4
Magnesium Bicarbonate
Mg(HCO3)2
White White
White Magnesium
carbonate residue
Carbon dioxide 
Colourless, odourless, slightly acidic to litmus
and turns lime water milky
Water Vapour
Neutral vapours turn Cobalt Chloride paper
blue to pink
Eqn
: Mg(HCO3) 2  MgCO3 +
H2O+ CO2
Note: Calcium bicarbonate and Magnesium bicarbonate exists only in solution
4. NITRATES
Name of the compound Original Colour Final Colour Residue Gas evolved test

6. 6
Formula Equation
1
Sodium Nitrate
NaNO3
Colourless Pale yellow liquid Pale yellow liquid
Oxygen 
Colourless, odourless neutral gas, rekindles a
glowing splinter
Eqn
: 2NaNO3  2NaNO2 + O2
2
Potassium Nitrate
KNO3
Colourless Pale yellow liquid Pale yellow liquid
Oxygen 
Colourless, odourless neutral gas, rekindles a
glowing splinter
Eqn
: 2KNO3  2KNO2 + O2
3
Calcium Nitrate
Ca(NO3)2
Colourless White
White residue of calcium
oxide
Oxygen 
Colourless, odourless neutral gas, rekindles a
glowing splinter
Nitrogen dioxide 
Reddish brown acidic gas
Turns Potassium Iodide paper brown in colour
Eqn
: 2Ca(NO3)2  2CaO + 4NO2 + O2
4
Zinc Nitrate
Zn(NO3)2
Colourless
Yellow when hot white
when cold
White residue of Zinc oxide
obtained on cooling
Oxygen 
Colourless, odourless neutral gas, rekindles a

7. 7
glowing splinter
Nitrogen dioxide 
Reddish brown acidic gas
Turns Potassium Iodide paper brown in colour
Eqn
: 2Zn(NO3)2  2ZnO + 4NO2 + O2
5
Lead Nitrate
Pb(NO3)2
White Yellow
Yellow residue of lead
monoxide fuses with the
test tube
Oxygen 
Colourless, odourless neutral gas, rekindles a
glowing splinter
Nitrogen dioxide 
Reddish brown acidic gas
Turns Potassium Iodide solution brown in
colour
Eqn
: 2Pb(NO3)2  2PbO + 4NO2 + O2
6
Copper Nitrate
Cu(NO3)2
Blue Black
Black residue of copper
oxide
Oxygen 
Colourless, odourless neutral gas, rekindles a
glowing splinter
Nitrogen dioxide 
Reddish brown acidic gas
Turns Potassium Iodide solution brown in
colour
Eqn
: 2Pb(NO3)2  2PbO + 4NO2 + O2
7
Mercuric Nitrate
Hg(NO3)2
Colourless Silvery
Silvery residue of mercury
on the test tube
Oxygen 
Colourless, odourless neutral gas, rekindles a

8. 8
glowing splinter
Nitrogen dioxide 
Reddish brown acidic gas
Turns Potassium Iodide paper brown in colour
Eqn
: Hg(NO3)2  Hg + 2NO2 + O2
8
Silver Nitrate
AgNO3
Colourless Silver
Silvery residue of silver on
the test tube
Oxygen 
Colourless, odourless neutral gas, rekindles a
glowing splinter
Nitrogen dioxide 
Reddish brown acidic gas
Turns Potassium Iodide paper brown in colour
Eqn
: 2AgNO3  2Ag + 2NO2 + O2
9
Ammonium Nitrate
NH4NO3
White No residue
Completely disappears on
heating
Nitrous Oxide 
(laughing gas)
Water Vapour 
Neutral vapours turn Cobalt Chloride paper
blue to pink
Eqn
: NH4NO3  2H2O + N2O
5. HYDROUS SALTS
Name of the compound Original Final Colour Residue Gas evolved test

9. 9
Formula Colour Equation
A
Hydrated Copper
Sulphate
CuSO45H2O
Blue
crystalline
compound
White anhydrous powder
Greyish white residue
of copper Sulphate.
On strong heating the
residue turns black
Water vapour
Neutral vapours turn Cobalt Chloride paper blue to pink
Eqn
: CuSO45H2O  CuSO4 + 5H2O
B
Hydrated Sodium
Carbonate
Na2CO310H2O
White
crystalline
solid
White anhydrous powder
White anhydrous
residue of sodium
carbonate
Water vapour
Neutral vapours turn Cobalt Chloride paper blue to pink
Eqn
: Na2CO310H2O  : Na2CO3 + 10H2O
6. Other compounds
a
Ammonium
dichromate
(NH4)2Cr2O7
Orange
Decomposes with sparks
giving out heat and
forms a green fluffy
powder
Green powder of
chromic oxide
Water vapour
Neutral vapours turn Cobalt Chloride paper blue to pink
Nitrogen
Colourless neutral gas
Eqn
: (NH4)2Cr2O7  : Cr2O3 + N2 + 4H2O
b
Ammonium Chloride
NH4Cl
White solid
Disappears from the
bottom of the test tube
and settles down as a
white solid on the upper
cooler parts of the test
tube
No residue at the
bottom of the test tube
Ammonia
Basic gas turns red litmus blue and gives dense white
fumes with a glass rod dipped in HCl
Hydrogen Chloride
An acidic gas gives dense white fumes with a glass rod
dipped in Ammonium Hydroxide
Eqn
: NH4Cl  NH3+ HCl
Iodine – Camphor – Naphthalene do not undergo any chemical change when heated, but undergo sublimation
Eg: Iodine crystals  Iodine vapour

10. 10