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5 (a) Name the type of reaction that takes place when calcium carbonate is heated strongly - AQA - GCSE Chemistry - Question 5 - 2014 - Paper 1
Question 5
5 (a) Name the type of reaction that takes place when calcium carbonate is heated strongly. Name the products formed. 5 (b) A student investigated what happens when... show full transcript
Worked Solution & Example Answer:5 (a) Name the type of reaction that takes place when calcium carbonate is heated strongly - AQA - GCSE Chemistry - Question 5 - 2014 - Paper 1
Step 1
Name the type of reaction that takes place when calcium carbonate is heated strongly. Name the products formed.
Answer
The reaction that takes place when calcium carbonate (CaCO₃) is heated strongly is known as thermal decomposition. The products formed from this reaction are calcium oxide (CaO) and carbon dioxide (CO₂).
Step 2
Calculate the mean mass lost, taking account of any anomalies.
Answer
To calculate the mean mass lost, we first need the individual mass losses from each experiment:
- Experiment 1: 1.8 g
- Experiment 2: 1.0 g
- Experiment 3: 1.9 g
- Experiment 4: 1.7 g
Now we calculate the mean:
Mean mass lost = rac{1.8 + 1.0 + 1.9 + 1.7}{4}
Mean mass lost = rac{6.4}{4}
Mean mass lost = 1.6 g.
Therefore, the mean mass lost, accounting for the anomalies (notably experiment 2 with the significant drop), is 1.6 g.
Step 3
The student used the chemical equation to calculate the maximum mass lost by 5.0 g of calcium carbonate when heated. The maximum mass lost is 2.2 g. Suggest and explain two reasons why the mean mass lost in the experiments to heat limestone is less than 2.2 g.
Answer
Reason 1: The limestone may not be pure and could contain impurities, which means that not all of the mass would convert to carbon dioxide upon heating, resulting in a lower mass loss.
Reason 2: The heating temperature may not have been high enough to fully decompose all of the calcium carbonate. If not heated long enough, incomplete decomposition occurs, leaving some unreacted substance, thus reducing the mass lost.