Salt preparations
3 marks · NormalA student is given a sample of calcium hydroxide and is told that calcium hydroxide is only slightly soluble in water. Using the solubility rules, calculate how many of the following compounds are soluble in water:
| Compound |
|---|
| Sodium nitrate |
| Barium sulfate |
| Potassium carbonate |
| Calcium sulfate |
| Ammonium chloride |
State the total number of compounds from the table that are soluble in water.
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3 (±0)
Common mistakes: Counting calcium sulfate or barium sulfate as soluble
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Marking points
M1 · 1 mark · Applies correct solubility rules to each compound.
M1 · 1 mark · Correctly identifies sodium nitrate, potassium carbonate and ammonium chloride as soluble.
A1 · 1 mark · Correct final answer: 3 soluble compounds.
Worked solution
Sodium nitrate: All nitrates are soluble. (soluble)
Barium sulfate: Barium sulfate is insoluble. (insoluble)
Potassium carbonate: All potassium compounds are soluble. (soluble)
Calcium sulfate: Calcium sulfate is insoluble. (insoluble)
Ammonium chloride: All ammonium compounds are soluble. (soluble)
So, 3 compounds are soluble in water.