Question

Identify the salt Q from the following observation.

Salt Q is white in colour. On strong heating, it produces buff yellow residue and liberates reddish brown gas solution ofsalt Q produces a chalky white insoluble precipitate with excess of ammonium hydroxide.

Answer 1

Observations:

• Strong heating leaves a buff yellow residue (PbO) and releases a reddish-brown gas (NO₂), which confirms the salt is a Nitrate \[\ce{(NO^-3)}\].
• Forming a chalky white precipitate insoluble in excess ammonium hydroxide confirms the cation is Lead (Pb²⁺).

Chemical Equation:

\[\ce{2Pb(NO3)2 ->[\Delta] \underset{Buff yellow (cold)}{2PbO} + \underset{Reddish-brown gas}{4NO2 ^} + O2^}\]

Salt Q is Lead nitrate [Pb(NO₃)₂].