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3 Quantitative chemistry

3 Quantitative chemistry

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Question 64

An investigator studied the thermal decomposition of magnesium carbonate.

The word equation for the reaction is:

magnesium carbonate→magnesium oxide+carbon dioxide \text{magnesium carbonate} \rightarrow \text{magnesium oxide} + \text{carbon dioxide} magnesium carbonate→magnesium oxide+carbon dioxide

The experimental procedure was as follows:

  1. Add 4.2 g4.2\text{ g}4.2 g of magnesium carbonate to an empty crucible.
  2. Record the combined mass of the crucible and its contents.
  3. Heat the crucible and contents strongly with a Bunsen burner for 1 minute.
  4. Allow the crucible and contents to cool down.
  5. Record the mass of the crucible and its contents.
  6. Repeat the heating, cooling, and weighing steps until a constant mass is reached.

The table below shows the results obtained during the investigation:

Total heating time (minutes)Mass of crucible and contents (g)
038.4
137.1
236.4
336.4
a.

Determine the mass of the empty crucible.

[2]
b.

Explain why the mass of the crucible and its contents decreased during heating.

[2]
c.

Suggest why the crucible and its contents were heated until the mass did not change.

[1]
d.

When 150 g150\text{ g}150 g of magnesium carbonate is completely decomposed, 178 kJ178\text{ kJ}178 kJ of energy is taken in. The student heated 4.20 g4.20\text{ g}4.20 g of magnesium carbonate until the mass did not change. Calculate the energy taken in during this reaction. Give your answer to 3 significant figures.

[3]
e.

What type of reaction takes place when magnesium carbonate is heated?

[1]
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3 Quantitative chemistry Questions

  1. GCSE
  2. /Chemistry
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