IB Chemistry HL 1.5.3 Molar Volume Question Bank

Practise IB Chemistry HL 1.5.3 with questions converting gas volume and amount using molar-volume conditions and units.

Exam points

convert between gas amount and volume using the molar volume stated for the conditions
compare pressure or volume changes using ratios of absolute temperature rather than Celsius
interpret gas-variable graphs while identifying which quantities are held constant

[Maximum number: 1]

Two hydrides of nitrogen are ammonia and hydrazine, $\mathrm{N}_{2} \mathrm{H}_{4}$ . One derivative of ammonia is methanamine whose molecular structure is shown below.

Figure for Question 1.5.3—Molar volume question 1 — IB Chemistry HL

Calculate, showing your working, the mass of hydrazine needed to remove all the dissolved oxygen from $1000 \mathrm{dm}^{3}$ of the sample.

Calculate the volume, in $\mathrm{dm}^{3}$ , of nitrogen formed under SATP conditions.
(The volume of 1 mol of gas $=24.8 \mathrm{dm}^{3}$ at SATP.)

$n(\mathrm{N}_{2}\mathrm{H}_{4})=n(\mathrm{O}_{2}) =\frac{8.0\ \mathrm{g}}{32.00\ \mathrm{g\ mol^{-1}}} =0.25\ \mathrm{mol}$ $\text{volume of nitrogen} =0.25\ \mathrm{mol}\times24.8\ \mathrm{dm^{3}\ mol^{-1}} =6.2\ \mathrm{dm^{3}}$

Award [1] for the correct final answer.

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1.5.3—Molar volume question 1