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Reaction of metal ions in salt solutions with sodium chloride, sodium sulphate and sodium sulphite

Answer Text:
Reaction of metal ions in salt solutions with sodium chloride, sodium sulphate and sodium sulphite
(i). Procedure
- #2cm^3# of a 0.1M solution containing lead ions is placed in a test tube.
- 2-3 drops of 2M sodium chloride solution are added and the mixture warmed;
- The procedure is repeated using salt solutions
containing #Ba^(2+) ;Mg^(2+); Ca^(2+); Zn^(2+); Cu^(2+); Fe^(2+) and Fe^(3+)#
- Each experiment (for each salt) is repeated using #Na_2SO_4# and #Na_2SO_3# respectively, in place of sodium chloride.
(ii). Observations
Explanations
- All the listed cations soluble salts except #Ba^(2+)# and #Pb^(2+)#
- Lead sulphate and barium sulphate are insoluble in water;
- Lead chloride and barium sulphite are insoluble; however #PbCl_2(s)# dissolves on warming
Equations:
#Pb^(2+)(aq) + 2Cl^(-)(aq) to PbCl_2(s)#
#Pb^(2+) (aq) + SO_4^(2-)(aq) to PbSO_4(s)#
#Ba^(2+)(aq) + SO_4^(2-)(aq) to BaSO_4(s)#
#Ba^(2+)(aq) + SO_3^(2-)(aq) to BaSO_3(s)#
Note:
- To distinguish the precipitate of barium sulphate from barium sulphite; dilute# HNO_3 (aq)# or HCl(aq) is added to both;
- #BaSO_3(s)# will dissolve in the dilute acid but barium sulphate will not.