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) Magnesium burns in excess oxygen to form magnesium oxide. The balanced equation for this reaction is 2Mg + O$_2$ → 2MgO Starting with 1.35g of magnesium, calculate the maximum mass of magnesium oxide that could be formed in this reaction. (relative atomic masses: O = 16.0, Mg = 24.0) You must show your working.

GCSE Edexcel Chemistry The mole: An aluminium atom has the atomic

An aluminium atom has the atomic number 13 and the mass number 27 - Edexcel - GCSE Chemistry - Question 3 - 2019 - Paper 1

Question 3

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) Ma... show full transcript

Worked Solution & Example Answer:An aluminium atom has the atomic number 13 and the mass number 27 - Edexcel - GCSE Chemistry - Question 3 - 2019 - Paper 1

Step 1

Which row shows the numbers of subatomic particles present in an aluminium ion, Al$^{3+}$?

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Answer

To identify the correct row:

An aluminium ion has an atomic number of 13, which means it has 13 protons.
The mass number is 27, thus the number of neutrons can be calculated by subtracting the atomic number from the mass number: $ext{Neutrons} = ext{Mass Number} - ext{Atomic Number} = 27 - 13 = 14.$
The charge of the ion does not change the number of electrons initially present. An Al $^{3+}$ ion loses 3 electrons, therefore: $ext{Electrons} = ext{Atomic Number} - 3 = 13 - 3 = 10.$

Thus, the correct row shows 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.

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Answer

To solve this problem:

Calculate moles of magnesium: $n = rac{ ext{mass}}{ ext{molar mass}} = rac{1.35 ext{ g}}{24.0 ext{ g/mol}} = 0.05625 ext{ moles}.$
From the balanced equation, 2 moles of Mg produce 2 moles of MgO. This indicates a 1:1 ratio. Therefore, moles of magnesium oxide that can be formed is also 0.05625 moles.
Calculate the mass of magnesium oxide produced: $ext{mass} = ext{moles} imes ext{molar mass of MgO} ext{ (where molar mass of MgO = 24.0 + 16.0 = 40.0 g/mol)}.$ $ext{mass} = 0.05625 ext{ moles} imes 40.0 ext{ g/mol} = 2.25 ext{ g}.$

Therefore, the maximum mass of magnesium oxide that could be formed is 2.25 g.

An aluminium atom has the atomic number 13 and the mass number 27 - Edexcel - GCSE Chemistry - Question 3 - 2019 - Paper 1

Worked Solution & Example Answer:An aluminium atom has the atomic number 13 and the mass number 27 - Edexcel - GCSE Chemistry - Question 3 - 2019 - Paper 1

Which row shows the numbers of subatomic particles present in an aluminium ion, Al$^{3+}$?

Starting with 1.35g of magnesium, calculate the maximum mass of magnesium oxide that could be formed in this reaction.

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