InterviewSolution
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InterviewSolution
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What do you observe when caustic soda solution is added to the following solution, first a little and then in excess:(a) FeCI3(b) ZnSO4(c) Pb(NO3)2(d) CuSO4Write balanced equations for these reactions. |
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Answer» (i) FeCI3 + 3NaOH ⟶ Fe(OH)3 ↓ 3 NaCI Yellow reddish brown, ppt colourless in solution In excess of alkali, the reddish brown ppt, of Fe(OH)3 remains insoluble (ii) ZnSO4 + 2NaOH ⟶ Zn(OH)2 ↓ + NaSO4 Colourless white gelatinous ppt. colourless In excess of alkali, white gelatinous ppt. of Zn(OH)2 becomes soluble Zn(OH)2 + 2NaOH (Excess) ⟶ Na2ZnO2 + 2H2O Sodium zincate (colourless) (iii) Pb(NO3)2 + 2NaOH ⟶ Pb(OH)2 ↓ + 2NaNO3 White ppt (colourless) In excess of alkali, white precipitate of Pb(OH)2 becom essoluble: Pb(OH)2 + 2NaOH(excess) ⟶ Na2PbO2 + 2H2O Sodium plumbate {colourless} CuSO4 + 2NaOH ⟶ Cu(OH)2↓ + 2NaSO4 Blue colourless pale blue ppt. { colourless} In excess of alkali, pale blue precipitate of Cu(OH)2 is insoluble |
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