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3 (a) An aluminium atom has the atomic number 13 and the mass number 27 - Edexcel - GCSE Chemistry - Question 3 - 2019 - Paper 1
Question 3
3 (a) 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)... show full transcript
Worked Solution & Example Answer:3 (a) An aluminium atom has the atomic number 13 and the mass number 27 - Edexcel - GCSE Chemistry - Question 3 - 2019 - Paper 1
Step 1
a) Which row shows the numbers of subatomic particles present in an aluminium ion, Al^3+?
Answer
An aluminium ion, Al^3+, has lost 3 electrons from the neutral atom configuration. Therefore, it has:
- Protons: 13 (remains unchanged)
- Neutrons: 14 (calculated as mass number 27 - atomic number 13)
- Electrons: 10 (13 - 3)
Thus, the correct option is (B) 13 protons, 14 neutrons, and 10 electrons.
Step 2
b) 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:
ext{Moles of Mg} = rac{ ext{mass}}{ ext{molar mass}} = rac{1.35 ext{ g}}{24.0 ext{ g/mol}} = 0.05625 ext{ mol}
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From the balanced equation, 2 moles of Mg produce 2 moles of MgO. Therefore, the moles of MgO produced will also be 0.05625 mol.
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Calculate the mass of magnesium oxide produced:
ext{Moles of MgO} = 0.05625 ext{ mol} imes 40.0 ext{ g/mol} (molar mass of MgO = 24.0 + 16.0) ext{Mass of MgO} = 2.25 ext{ g}
Thus, the maximum mass of magnesium oxide that could be formed is 2.25 g.