DP Chemistry (first assessment 2025)

Question 19M.2.SL.TZ2.3b(ii)

Date	May 2019	Marks available	[Maximum mark: 2]	Reference code	19M.2.SL.TZ2.3b(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.TZ2.3b(ii)

(b(ii))

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

Structure 3. Classification of matter » Structure 3.2—Functional groups: Classification of organic compounds » Structure 3.2.8—Mass spectrometry (MS) of organic compounds can cause fragmentation of molecules. Deduce information about the structural features of a compound from specific MS fragmentation patterns.

Question 19M.2.SL.TZ2.3b(ii)

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