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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.