Acids, Bases and Salt Preparations
6 marks · NormalState the general word equation for the reaction between an acid and a carbonate.
A student reacts magnesium carbonate with dilute hydrochloric acid. Name the gas that is produced in this reaction.
Ammonium carbonate is one example of a soluble carbonate. Using your knowledge of solubility rules, name two other types of carbonates that are also soluble in water.
Give a reason, using solubility rules, why lead(II) carbonate is not a suitable choice to make a soluble salt by the reaction with an acid.
Work this out on paper, then compare with the answer and worked solution below. With a free account you can submit written answers for marking.
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(a) acid + carbonate → salt + water + carbon dioxide
(b) carbon dioxide
(c) Any two from: sodium carbonate, potassium carbonate, ammonium carbonate
(d) Lead(II) carbonate is insoluble in water, so it cannot be used to make a soluble salt by reacting with an acid; the salt solution will be contaminated by insoluble residue.
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Marking points
B1 (a) · 1 mark · Correct general word equation: 'acid + carbonate → salt + water + carbon dioxide'.
B1 (b) · 1 mark · Correctly names carbon dioxide as the gas produced.
B1 (c) · 2 marks · Names any two: sodium carbonate, potassium carbonate, ammonium carbonate (1 mark each).
B1 (d) · 2 marks · Gives correct reason based on insolubility and consequence for salt preparation (separates point for insolubility and consequence).
Worked solution
(a) The general word equation is:
(b) The gas produced is carbon dioxide.
(c) From the solubility rules: sodium carbonate, potassium carbonate, and ammonium carbonate are all soluble in water. Any two of these are correct.
(d) Lead(II) carbonate is insoluble in water. This means it cannot be used to make a soluble salt by reaction with an acid, because the product (the salt) would be mixed with insoluble residue, making separation difficult.