Metals and non-metals in the periodic table

2 marks · Easy

An oxide of aluminium (Al) reacts with hydrochloric acid to produce 27 grams of aluminium chloride. Given the information below, use the periodic table and your knowledge of metals and oxides to calculate the number of moles of aluminium chloride formed. (Al = 27, Cl = 35.5)

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0.2 mol (±0.01)

Also accept: 0.20 mol

Common mistakes: Incorrect RFM calculation; Wrong formula

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Marking points

M1 · 1 mark · Calculates relative formula mass (RFM) of aluminium chloride (AlCl3) correctly: 27 + (35.5 × 3) = 133.5. (follow-through)

A1 · 1 mark · Correctly calculates number of moles: mol (accept alternative accurate rounding). (follow-through)

Worked solution

Relative formula mass (RFM) of aluminium chloride (AlCl3):

Number of moles = mass / RFM = 27 / 133.5 = 0.202 mol (rounded to 0.2 mol).