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An aluminium atom has the atomic number 13 and the mass number 27 - Edexcel - GCSE Chemistry Combined Science - Question 2 - 2019 - Paper 1
Question 2
An aluminium atom has the atomic number 13 and the mass number 27. Which row shows the numbers of subatomic particles present in an aluminium ion, Al^{3+}? (b) Magn... show full transcript
Worked Solution & Example Answer:An aluminium atom has the atomic number 13 and the mass number 27 - Edexcel - GCSE Chemistry Combined Science - Question 2 - 2019 - Paper 1
Step 1
Which row shows the numbers of subatomic particles present in an aluminium ion, Al^{3+}?
Answer
An aluminium ion, Al^{3+}, has lost three electrons. Given the atomic number is 13, the number of protons is 13, and for neutrons, we subtract the atomic number from the mass number: Mass number = Protons + Neutrons 27 = 13 + Neutrons Neutrons = 27 - 13 = 14. Thus, the correct row is B: 13 protons, 14 neutrons, and 10 electrons.
Step 2
Starting with 1.35g of magnesium, calculate the maximum mass of magnesium oxide that could be formed in this reaction.
Answer
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Calculate the moles of magnesium:
Moles of Mg = rac{mass}{molar mass} = rac{1.35g}{24.0g/mol} = 0.05625 mol.
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From the balanced equation 2Mg + O_2 → 2MgO, the mole ratio of Mg to MgO is 1:1. Therefore, 0.05625 mol of Mg will produce 0.05625 mol of MgO.
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Calculate the maximum mass of magnesium oxide using the formula:
Mass = Moles × Molar Mass
Molar mass of MgO = 24.0 + 16.0 = 40.0 g/mol.
Maximum mass of MgO = 0.05625 mol × 40.0 g/mol = 2.25g.
Step 3