Chemistry · S and p Block Elements
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When dilute hydrochloric acid is added to aqueous solution of a compound X, a colourless gas is evovled which rapidly decolourises acidified, aqueous potassium manganate (VII). Which of the following compounds could be X?
- A
Sodium carbonate
- B
Sodium chlorate (I)
- C
Sodium nitrite
- D
Sodium sulphate
- E
Sodium sulphite
Sodium sulfite (NaSO3) and hydrochloric acid (HCl) are mixed to create sulphur dioxide gas (SO2). SO2 readily decolourises acidified KMnO4 solution. KMnO4 has a purple colour. Sulphur dioxide gas acts as a reducing agent whereas KMnO4 is an oxidising agent and gets decolourized.
When sodium carbonate reacts with hydrochloric acid, it produces carbon dioxide (CO2), water, and sodium chloride. CO2 does not decolourise acidified potassium manganate (VII).
Sodium chlorate reacts with hydrochloric acid to produce sodium chloride, chlorine gas (Cl2), and water. Chlorine does not decolourise acidified potassium manganate (VII).
Sodium nitrite reacts with hydrochloric acid to produce sodium chloride, nitrogen dioxide (NO2), and nitric acid. NO2 does not decolourise acidified potassium manganate (VII).
Sodium sulfate does not release any gas when reacted with hydrochloric acid, as the reaction is essentially a neutralization that results in sodium chloride and sulfuric acid.
Sodium sulphite reacts with hydrochloric acid to produce sodium chloride, water, and sulphur dioxide gas (SO2). SO2 readily decolourises acidified potassium manganate (VII) as it acts as a reducing agent.
Tagged under Chemistry · S and p Block Elements · 2016