Salt preparations
2 marks · NormalState the solubility rules for (i) all chlorides, and (ii) all hydroxides, in water.
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(i) All common chlorides are soluble except silver chloride and lead(II) chloride. (ii) All metal hydroxides are insoluble except sodium, potassium and ammonium hydroxides; calcium hydroxide is slightly soluble.
Must show: 2 clear correct statements
Also accept: Alternative wording accepted if correct details given.
Common mistakes: Missing exceptions for chlorides; Not stating exceptions for hydroxides
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Marking points
B1 · 1 mark · States chloride rule with exceptions (all common chlorides soluble except AgCl and PbCl2).
B2 · 1 mark · States hydroxide rule and exceptions (all metal hydroxides insoluble except sodium, potassium, ammonium; calcium hydroxide slightly soluble).
Worked solution
(i) All common chlorides are soluble, except silver chloride and lead(II) chloride.
(ii) All metal hydroxides are insoluble, except those of sodium, potassium and ammonium, which are soluble; calcium hydroxide is slightly soluble.