Question

Distinguish by adding:

Sodium hydroxide solution or ammonium hydroxide solution to ferrous salt solution and lead salt solution

Answer 1

Sodium hydroxide on reaction with ferrous salt solution gives a dirty green precipitate of Fe(OH)₂ which is insoluble in excess NaOH.

\[\ce{\underset{Colourless/light green}{FeSO4} + 2NaOH -> \underset{dirty green ppt}{Fe(OH)2\downarrow} + Na2SO4}\]

Sodium hydroxide on reaction with lead salt solution gives a white precipitate of Pb(OH)₂.

\[\ce{\underset{Colourless}{Pb(NO3)2} + 2NaOH -> \underset{Chalky white ppt}{Pb(OH)2\downarrow} + 2NaNO3}\]