What do you observe when caustic soda solution is added to the following solution, first a little and then in excess:
(a) FeCl3,
(b) ZnSO4,
(c) Pb(NO3)2,
(d) CuSO4 ?
Write balanced equations for these reactions.
(i) FeCI3+3NaOH⟶Fe(OH)3↓3NaCI
In excess of alkali, the reddish brown ppt, of Fe(OH)3 remains insoluble
(ii) ZnSO4+2NaOH⟶Zn(OH)2↓+NaSO4
In excess of alkali, white gelatinous ppt. of Zn(OH)2 becomes soluble
Zn(OH)2+2NaOH(Excess)⟶Na2ZnO2+2H2O
(iii) Pb(NO3)2+2NaOH⟶Pb(OH)2↓+2NaNO3
In excess of alkali, the white precipitate of Pb(OH)2 become soluble:
Pb(OH)2+2NaOH(excess)⟶Na2PbO2+2H2O
(iv)CuSO4+2NaOH⟶Cu(OH)2↓+2NaSO4
In excess of alkali, the pale blue precipitate of Cu(OH)2 is insoluble