Question

State one chemical test between the following pair:

Sodium carbonate and sodium sulphite

Answer 1

A colourless and odourless gas is produced when sodium carbonate and dil. sulphuric acid are combined; this gas has no effect on acidified potassium dichromate paper.

\[\ce{Na2CO3 + H2SO4 -> Na2SO4 + H2O + CO2}\]

Add sodium sulphite to a diluted solution. Sulphuric acid releases a colourless gas with a burning sulphur odour and changes acidified potassium dichromate paper from orange to green.

\[\ce{Na2SO3 + H2SO4 -> Na2SO4 + H2O + SO2}\]

\[\ce{\underset{(Orange)}{K2Cr2O7} + 3SO2 + H2SO4 -> K2SO4 + \underset{(Green)}{Cr2(SO4)3 + H2O}}\]