Making predictions using the reactivity series
3 marks · NormalIndium is a metal that reacts slowly with hot dilute hydrochloric acid. Its position is just above hydrogen in the reactivity series.
A student adds 0.050 mol of indium to excess hydrochloric acid.
Calculate the volume of hydrogen gas formed at room temperature and pressure (RTP). (1 mol of gas occupies 24 dm³ at RTP.)
Work this out on paper, then compare with the answer and worked solution below. With a free account you can submit written answers for marking.
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0.050 mol In produces 0.075 mol H2; volume is 1.8 dm³ (±0.02)
Must show: Correct balanced equation: 2In + 6HCl → 2InCl3 + 3H2
Common mistakes: Incorrect stoichiometric ratio; Using wrong molar volume
Show mark scheme and worked solution
Marking points
M1 · 1 mark · Writes balanced equation: 2In + 6HCl → 2InCl3 + 3H2
M2 · 1 mark · Calculates moles of H2 correctly (0.075 mol from 0.050 mol In) (follow-through)
A1 · 1 mark · Converts moles of H2 to correct gas volume (1.8 dm³) (follow-through)
Worked solution
Balanced equation:
Ratio: 2 mol In gives 3 mol H2, so 0.050 mol In gives:
Volume = moles × molar volume = 0.075 × 24 = 1.8 dm³