Question

Question #370a7

Answer 1

`Pb_((aq))^(2+)+2OH_((aq))^(-)rarrPb(OH)_(2(s))`

Explanation:

By `NH_3` I am assuming you mean ammonia solution.

This partly ionises in water to give ammonium and hydroxide ions:

`NH_(3(g))+H_2O_((l))rightleftharpoonsNH_(4(aq))^(+)+OH_((aq))^(-)`

A white precipitate of lead(II) hydroxide is formed if aqueous lead(II) ions are added:

`Pb_((aq))^(2+)+2OH_((aq))^(-)rarrPb(OH)_(2(s))`

The same reaction happens with `NaOH` solution.

The sodium ions remain in solution as spectator ions.

If XS sodium hydroxide is added the precipitate redissolves to give the soluble plumbate(II) ion.

A simple way of writing this is:

(chemguideUK)

Ammonia solution can't do this as the concentration of `OH^(-)` ions is not high enough.