of S , S & S and small amount of mixture of S , S , S , S molecules. XII XII - - - - . . Sulphur dioxide Preparation From sulphur: A large-scale production of sulphur dioxide is done by burning sulphur in air.
About - % of sulphur is oxidised to SO . S + O SO 2S + 3O 2SO From sulphides: When sulphide ores such as galena (PbS), zinc blende (ZnS) are roasted in air, sulphur dioxide is liberated. Large amounts of sulphur dioxide required for manufacturing of sulphuric acid and other industrial purpose is prepared by this method. 2ZnS + 3O 2ZnO + 2SO 4FeS + 11O 2Fe O + 8SO ∆ ∆ Laboratory preparation: Sulphur dioxide is prepared in the laboratory treating a metal or metal sulphite with sulphuric acid Cu + 2H SO CuSO + SO + 2H O SO - + 2H + H O + SO Properties: Sulphur dioxide gas is found in volcanic eruptions.
A large amount of sulphur dioxide gas is released into atmosphere from power plants using coal and oil and copper melting plants. It is a colourless gas with a suffocating odour. It is highly soluble in water and it is . times heavier than air.
Sulphur dioxide can be liquefied (boiling point K) at . atmospheric pressure and K. Chemical properties Sulphur dioxide is an acidic oxide. It dissolves in water to give sulphurous acid.
SO + H O H SO H SO Sulphurous acid ⇀ ↽ ⇀ ↽ 2H + SO − Reaction with sodium hydroxide and sodium carbonate: Sulphur dioxide reacts with sodium hydroxide and sodium carbonate to form sodium bisulphite and sodium sulphite respectively. SO + NaOH NaHSO 2SO + Na CO H O Sodium bisulphite 2NaHSO + CO NaHSO Na SO + H O Sodium sulphite + SO Oxidising property: Sulphur dioxide, oxidises hydrogen sulphide to sulphur and magnesium to magnesium oxide. 2H S + SO 3S + 2H O 2Mg +