Practical Work
Detection of Some Gases
Test for hydrogen (H2):
Hydrogen gas is liberated when active metals such as Na, K, Mg react with dilute acids.
Few characteristics of this gas are as follows.
i. It is a colourless and odourless gas.
ii. When this gas is allowed to pass through a moist red or blue litmus paper, the colour of the paper does not change. This shows that hydrogen gas is neutral to litmus.
iii. A burning wooden splint, when brought near this gas, gets off and burns with a pale blue flame producing a pop sound.
Test for oxygen (O2):
Oxygen gas is liberated on heating metal nitrates, potassium chlorate, potassium dichromate, potassium permanganate, hydrogen peroxide, barium peroxide and oxides such as HgO, PbO2, Pb3O4.
Few characteristics of this gas are as follows.
i. It is a colourless and odourless gas.
ii. When this gas is allowed to pass through a moist red or blue litmus paper, the colour of the paper does not change. This shows that oxygen gas is neutral to litmus.
iii. A burning wooden splint when brought near this gas re-lights brightly which shows that it is a supporter of combustion.
Test for water vapour (H2O):
Water vapour is liberated on heating salts containing water of crystallisation, metallic hydroxides and metallic hydrogen carbonates.
Few characteristics of this gas are as follows.
i. It is a colourless and odourless gas.
ii. When this gas is allowed to pass through a moist red or blue litmus paper, the colour of the paper does not c…
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