give the characteristic test of the following gases co2, o2 and H2
Answers
The Characteristic test for
(i) Carbon dioxide (CO2,) gas turns lime water milky when passed through it due to the formation of insoluble calcium carbonate.
Limewater
Ca(OH)
2
+
Carbondioxide
CO
2
→
Calciumcarbonate
CaCO
3
+H
2
O
(ii) Sulphur dioxide (SO2) gas when passed through acidic potassium permanganate solution (purple in colour) turns it colourless because SO
2
is a strong reducing agent.
PotassiumPermanganate(purple)
2KMnO
4
+2H
2
O+
Sulphurdioxide
5SO
2
→
PotassiumSulphate(Colourless)
K
2
SO
4
+
ManganeseSulphate(Colourless)
2MnSO
4
+2H
2
SO
4
(iii) The evolution of oxygen (O
2
) gas during a reaction can be confirmed by bringing a burning candle near the mouth of the test tube containing the reaction mixture. The intensity of the flame increases because oxygen supports burning.
(iv) Hydrogen (H
2
) gas burns with a pop sound when a burning candle is brought near it.