Sulphur dioxide is produced commercially on a vast scale by

Options

A. burning sulphur in air
B. buring hydrogen sulphide in air
C. roasting various metal sulphides
D. All of these

Answer

4

Explanation

`S(s)+O_(2)(g)rarrSO_(2)(g)`
`2H_(2)S+3O_(2)(g)rarr2H_(2)O(l)+2SO_(2)(g)`
Particularly `FeS_(2)` and to a smaller extent `CuS` and `ZnS` are roasted with air in smelters:
`4FeS_(2)+11O_(2)rarr2Fe_(2)O_(3)+8SO_(2)`
`2ZnS+3O_(2)rarr2ZnO+2SO_(2)`
Large amounts of `SO_(2)` are produced as a waste product by burning coal and to a lesser extent, other fossile fuels, oil and gas. This undoubtedly harms the environment. In the laboratory, it is prepared by heating copper with concentrated sulphuric acid :
`Cu(S)+2H_(2)SO_(4)rarrCuSO_(4)+2H_(2)O+SO_(2)uarr`
Side reactions occur and asome copper sulphide is formed .The gas is dried by passing it through cone. sulphuric acid and is collected upward displacement of air. (Silver metal also undergoes similar reaction
`2Ag+2H_(2)SO_(4) rarr Ag_(2)SO_(4)+2H_(2)O+SO_(2)`
Alternatively, it can be made by heating a solution of a sulphite or hydrosulphite with concentrated sulphuric acid or hydrochloric acid:
`NaSO_(3)+H_(2)SO_(4)rarrNa_(2)SO_(4)+H_(2)O+SO_(2)(g)`
or
`SO_(3)^(2-)(Aq.)+2H^(+)(aq.)rarrH_(2)O(l)+SO_(2)(g)`
`NaHSO_(3)+HCl rarr NaCl +H_(2)O+SO_(2)(g)`
or
`HSO_(3)^(-)(aq.)+H^(+)(aq.)rarr H_(2)O(l)+SO_(2)(g)`
Siphone of liquefied `SO_(2)` provide a convenient supply of the gas for laboratory use.