Reacting acids with carbonates
3 marks · NormalExplain, with reference to ions, why carbon dioxide and water are formed when a carbonate reacts with an acid. Write the ionic equation for this reaction.
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CO3^{2-}(aq) + 2H^+(aq) -> CO2(g) + H2O(l)
Common mistakes: Incorrect charges on ions; Incorrect number of hydrogen ions
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Marking points
M1 · 1 mark · States that carbonate ions react with hydrogen ions from the acid
M2 · 1 mark · Explains that this results in the formation of carbon dioxide and water
A1 · 1 mark · Correct ionic equation:
Worked solution
When a carbonate reacts with an acid, the carbonate ion (CO3^{2-}) reacts with two hydrogen ions from the acid.
This produces carbon dioxide gas and water.