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Reactions: Prediction and Synthesis
11. Devise methods for the laboratory preparation and isolation of each of the
following compounds in pure form and in good yield. Use pure metals as
starting materials.
(a) Pb(C 2 H 3 0 2 ) 2
(c) Ag 2 S0 4
(e) SnCl 2
(b) MgSO 4
(d) CdS
(f) A1 2 O 3
12. Describe the stepwise procedure (stating volumes and temperatures) that you
would use for the separation by two cycles of fractional crystallization for
each of the following solid mixtures. Calculate the number of grams of pure
salts obtained in each case. Solubility data are given in parentheses after each
compound; the first figure is for 0.0°C and the second for 100.0°C, both in
grams/100 ml of water: Ce 2 (SO 4 ) 3 (10.1, 2.3); NaBrO 3 (27.5, 90.9); NH 4 C10 4
(10.7, 47.3); Na 4 P 2 O 7 (3.2, 40.3); NH 4 C1 (29.7, 75.8); KC1 (27.9, 56.7); KC1O,
(3.8, 58.1); KNO 3 (13.3, 247).
(a) 100 g each of KC1O 3 and Ce 2 (SO 4 ) 3
(b) 100 g of KC1 and 50 g of NaBrO 3
(c) 50 g each of Na 4 P 2 O 7 and NH 4 C1
(d) 1 mole each of KNO 3 and NH 4 C1O 4