Carbon dioxide and global warming: the greenhouse effect
4 marks · NormalWhen magnesium carbonate is heated strongly, it decomposes.
Write a balanced chemical equation for the thermal decomposition of magnesium carbonate.
Name the type of reaction taking place.
Describe what would be observed when magnesium carbonate is heated in a test tube.
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) \ce{MgCO3(s) -> MgO(s) + CO2(g)}
(b) Thermal decomposition
(c) The white solid may turn to a different shade (grey or remain white but powdery) and a gas (carbon dioxide) is given off.
Common mistakes: Incorrect balancing; Not mentioning a gas is produced; Not naming reaction as thermal decomposition
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Marking points
A1 (a) · 1 mark · Correct balanced equation for the decomposition of magnesium carbonate.
B1 (b) · 1 mark · Thermal decomposition identified as the type of reaction.
M1 (c) · 1 mark · Describes a visible change, e.g. powder or change in appearance.
M2 (c) · 1 mark · Mentions the release of a gas such as carbon dioxide.
Worked solution
a) The balanced equation is:
b) The reaction is thermal decomposition.
c) Observations: The white solid may change slightly, and bubbles of a colourless gas (CO2) are produced.