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The symbol of an aluminium ion is Al³⁺ - OCR Gateway - GCSE Chemistry - Question 14 - 2020 - Paper 1

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The symbol of an aluminium ion is Al³⁺. The symbol of an oxide ion is O²⁻. What is the formula of aluminium oxide? A. AlO B. Al₂O C. Al₃O₂ D. Al₂O₃ Your answer

Worked Solution & Example Answer:The symbol of an aluminium ion is Al³⁺ - OCR Gateway - GCSE Chemistry - Question 14 - 2020 - Paper 1

Step 1

Identify the charges of ions

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Answer

The charge of the aluminium ion (Al) is +3 (Al³⁺) and the charge of the oxide ion (O) is -2 (O²⁻).

Step 2

Determine the ratio of ions

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Answer

To balance the charges, we need to find the least common multiple of the charges. The least common multiple of 3 and 2 is 6. Therefore, we need 2 aluminium ions and 3 oxide ions to achieve a neutral compound.

Step 3

Write the formula for aluminium oxide

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Answer

The resulting formula, with 2 aluminium ions and 3 oxide ions, is Al₂O₃.

Step 4

Select the correct option

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Answer

The correct formula for aluminium oxide is option D: Al₂O₃.

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