DP Chemistry (last assessment 2024)

Question 19M.2.sl.TZ2.b(ii)

Date	May 2019	Marks available	[Maximum mark: 2]	Reference code	19M.2.sl.TZ2.b(ii)
Level	sl	Paper	2	Time zone	TZ2
Command term	Calculate	Question number	b(ii)	Adapted from	N/A

b(ii).

[Maximum mark: 2]

19M.2.sl.TZ2.b(ii)

Dinitrogen monoxide, N₂O, causes depletion of ozone in the stratosphere.

Different sources of N₂O have different ratios of ¹⁴N:¹⁵N.

A sample of gas was enriched to contain 2 % by mass of ¹⁵N with the remainder being ¹⁴N.

Calculate the relative molecular mass of the resulting N₂O.

[2]

Markscheme

« $\frac{{(98 \times 14) + (2 \times 15)}}{{100}} =$ » 14.02 [✔]

«M_r = (14.02 × 2) + 16.00 =» 44.04 [✔]

Examiners report

Many candidates successfully calculated the relative atomic mass of nitrogen in the sample. M2 was awarded independently of M1, so candidates who calculated the relative molecular mass using the A_r of nitrogen in the data booklet (14.01) were awarded M2. Many candidates scored both marks.

Syllabus sections

Core

Core » Topic 2: Atomic structure » 2.1 The nuclear atom

Core » Topic 1: Stoichiometric relationships » 1.2 The mole concept

Core » Topic 1: Stoichiometric relationships

Core » Topic 2: Atomic structure

Question 19M.2.sl.TZ2.b(ii)

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