Chemistry
With the help of balanced equations - show how precipitation reactions are used for identifying the positive radicals in three different salts, each having a different cation [positive ion].
Chemical Reaction
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Answer
Precipitation reactions are used in analytical chemistry for identifying the positive radical in a salt by analysing the colour of the precipitate.
(i) FeSO4 + 2NaOH ⟶ Na2SO4 + Fe(OH)2 ↓
Identified ion: Fe2+; a dirty green precipitate of iron [II] hydroxide is obtained. Hence, it can be identified.
(ii) CuSO4 + 2NaOH ⟶ Na2SO4 + Cu(OH)2 ↓
Identified ion: Cu2+; a pale blue precipitate of copper [II] hydroxide is obtained. Hence, it can be identified.
(iii) Pb(NO3)2 + 2NaOH ⟶ 2NaNO3 + Pb(OH)2 ↓
Identified ion: Pb2+; a chalky white precipitate of lead [II] hydroxide is obtained. Hence, it can be identified.
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