Magnesium carbonate has the formula MgCO₃ - Edexcel - GCSE Chemistry - Question 9 - 2022 - Paper 1
Question 9
Magnesium carbonate has the formula MgCO₃.
(a) Magnesium carbonate contains Mg²⁺ and CO₃²⁻ ions.
(i) The atomic number of magnesium is 12.
What is the electronic ... show full transcript
Worked Solution & Example Answer:Magnesium carbonate has the formula MgCO₃ - Edexcel - GCSE Chemistry - Question 9 - 2022 - Paper 1
Step 1
What is the electronic configuration of the Mg²⁺ ion?
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Answer
The electronic configuration of magnesium (atomic number 12) is 2.8. In the Mg²⁺ ion, two electrons are lost from the outer shell (the 3rd shell), leaving the configuration as 2.8, which corresponds to option B.
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Answer
Solid magnesium carbonate cannot conduct electricity because it is an ionic compound where the ions are held in a fixed position in the lattice structure, preventing them from moving freely. In contrast, solid magnesium is a metal with free-moving electrons that can carry an electric current, allowing it to conduct electricity.
Step 3
Calculate the percentage by mass of magnesium in magnesium carbonate, MgCO₃.
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Answer
To calculate the percentage by mass of magnesium in magnesium carbonate (MgCO₃), we first determine the molar mass of the compound:
Molar mass of Mg = 24.0 g/mol
Molar mass of C = 12.0 g/mol
Molar mass of O = 16.0 g/mol × 3 = 48.0 g/mol
Total molar mass of MgCO₃ = 24.0 + 12.0 + 48.0 = 84.0 g/mol
Next, we calculate the percentage by mass of magnesium:
Percentage by mass of Mg=(Molar mass of MgCO₃Mass of Mg)×100=(84.024.0)×100≈28.57%
