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Magnesium carbonate has the formula MgCO<sub>3</sub> - Edexcel - GCSE Chemistry Combined Science - Question 6 - 2022 - Paper 1
Question 6
Magnesium carbonate has the formula MgCO<sub>3</sub>. (a) Magnesium carbonate contains Mg<sup>2+</sup> and CO<sub>3</sub><sup>2-</sup> ions. (i) The atomic number ... show full transcript
Worked Solution & Example Answer:Magnesium carbonate has the formula MgCO<sub>3</sub> - Edexcel - GCSE Chemistry Combined Science - Question 6 - 2022 - Paper 1
Step 1
What is the electronic configuration of the Mg<sup>2+</sup> ion?
Answer
The electronic configuration of the Mg<sup>2+</sup> ion is 2. This is because magnesium has an atomic number of 12, indicating it has 12 electrons. When it loses two electrons to form Mg<sup>2+</sup>, it has 10 electrons remaining, which are arranged as 2 in the first shell and 8 in the second shell.
Step 2
Explain why solid magnesium carbonate cannot conduct electricity but solid magnesium can.
Answer
Solid magnesium carbonate cannot conduct electricity because it is an ionic compound. In the solid state, the ions are held in a fixed position within a crystal lattice and cannot move freely. Therefore, there are no mobile charge carriers to allow the flow of electricity. In contrast, solid magnesium is a metal and contains delocalized electrons that are free to move within the metal structure. This allows solid magnesium to conduct electricity effectively.
Step 3
Calculate the percentage by mass of magnesium in magnesium carbonate, MgCO<sub>3</sub>.
Answer
To calculate the percentage by mass of magnesium in magnesium carbonate (MgCO<sub>3</sub>), we first determine the molar mass of MgCO<sub>3</sub>:
- 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 MgCO<sub>3</sub> = 24.0 + 12.0 + 48.0 = 84.0 g/mol
Now, we find the percentage by mass of magnesium:
Thus, the percentage by mass of magnesium in magnesium carbonate is approximately 28.57%.