DP Chemistry (first assessment 2025)

Question 19M.2.SL.TZ2.4c(ii)

Date	May 2019	Marks available	[Maximum mark: 2]	Reference code	19M.2.SL.TZ2.4c(ii)
Level	SL	Paper	2	Time zone	TZ2
Command term	Calculate	Question number	c(ii)	Adapted from	N/A

c(ii).

[Maximum mark: 2]

19M.2.SL.TZ2.4c(ii)

(c(ii))

Calculate the percentage, by mass, of rhenium in ReCl₃.

[2]

Markscheme

«M_r ReCl₃ = 186.21 + (3 × 35.45) =» 292.56 [✔]

«100 × $\frac{{186.21}}{{292.56}}$ =» 63.648 «%» [✔]

Examiners report

The majority of candidates calculated the percentage, by mass, of rhenium in ReCl₃ correctly. Some rounding errors were seen that students should be more careful with.

Syllabus sections

Structure 1. Models of the particulate nature of matter » Structure 1.4—Counting particles by mass: The mole » Structure 1.4.3—Molar mass M has the units g mol–1. Solve problems involving the relationships between the number of particles, the amount of substance in moles and the mass in grams.

Question 19M.2.SL.TZ2.4c(ii)

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