DP Chemistry (first assessment 2025)

Question 19N.2.SL.TZ0.2a(ii)

Date	November 2019	Marks available	[Maximum mark: 2]	Reference code	19N.2.SL.TZ0.2a(ii)
Level	SL	Paper	2	Time zone	TZ0
Command term	Calculate	Question number	a(ii)	Adapted from	N/A

a(ii).

[Maximum mark: 2]

19N.2.SL.TZ0.2a(ii)

(a(ii))

Calculate the number of moles of oxygen in the day 0 sample.

[2]

Markscheme

${{\text{n}}_{{{\text{s}}_2}{{\text{o}}_3}^{2 - }}} = «0.0258{\text{ d}}{{\text{m}}^3} \times 0.010{\text{ mol d}}{{\text{m}}^{ - 3}} =» 2.58 \times {10^{ - 4}}{\text{«mol»}}$ ✔

« $\frac{{2.58 \times {{10}^{ - 4}}{\text{mol}}}}{4} =» 6.45 \times {10^{ - 5}}{\text{«mol»}}$ ✔

NOTE: Award [2] for correct final answer.

Syllabus sections

Reactivity 2. How much, how fast and how far? » Reactivity 2.1—How much? The amount of chemical change » Reactivity 2.1.2—The mole ratio of an equation can be used to determine: • the masses and/or volumes of reactants and products • the concentrations of reactants and products for reactions occurring in solution. Calculate reacting masses and/or volumes and concentrations of reactants and products.

Question 19N.2.SL.TZ0.2a(ii)

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