Tests for gases

Question 1

Water vapour

Answer 1

1. turns blue cobalt chloride paper pink
2. White CuSO4 blue( anhydrous to hydrated)

Question 2

Hydrogen

Answer 2

1. Burns with a pale blue flame producing a pop sound
2. extinguishes burning splinter

Question 3

oxygen

Answer 3

1. rekindles -A glowing wooden splinter
2. Absorbed in colourless alkaline pyrogallol solution which turns brown

Question 4

carbon dioxide

Answer 4

1. Turn lime water Milky
2. has no effect on acidified potassium permanganate or potassium dichromate soln

Question 5

Sulphur dioxide

Answer 5

1. turns lime water Milky
2. turns potassium Permanganate pink to clear colourless
3. Turns potassium dichromate from orange to clear green

Question 6

chlorine

Answer 6

1.Greenish yellow gas
2. Turns moist blue litmus red and then bleaches it

Question 7

hydrogen chloride

Answer 7

1. Dense white fumes with Ammonia
2. Pungent odour
3. curdy white precipitate with silver nitrate solution

Question 8

hydrogen sulphide

Answer 8

1. rotten egg smell
2. potassium permanganate pink to colourless
3. Potassium dichromate orange to green
   [not clear as S particles are present]

Question 9

nitrogen dioxide

Answer 9

1.Reddish brown gas
2. dissolves in cold water to give a mixture of nitrous and nitrous acid- litmus test

Question 10

Ammonia

Answer 10

1. Dense white fumes with HCl
2. Nessler’s reagent K2HgI4 colourless to Pale brown
3. pale blue precipitate on passage through CuSO4 solution