Chemistry Paper 3 WASSCE (PC 2ND), 2018

Question 2

 

The table below was obtained by mixing solutions A, B, C and D, each containing
ZnSO4 (aq), Pb(NO3)2 (aq), NaOH (aq) and HCl (aq) but not necessarily in that order.

 

From the observations in the table, deduce the substances A, B, C and D, give reasons.

Observation

 

The expected answers include:

(a)

Substance A is HCl because it formed white precipitate with D (Pb(NO3)2) and no precipitate with B (ZnSO4)  and C (NaOH).

 

Substance B is ZnSO4 because it formed white gelatinous precipitate with C (NaOH), white precipitate with D Pb(NO3)2 and no precipitate with A (HCl) 

 

Substance C is NaOH because it formed a white precipitate with D (Pb(NO3)2), a white gelatinous precipitate with B (ZnSO4) and no precipitate with A (HCl) .

 

Substance D is Pb(NO3)2 because it formed white precipitate with A (HCl), white precipitate with B (ZnSO4)  white precipitate with C (NaOH).