DP Chemistry (last assessment 2024)

Question 18M.2.hl.TZ1.1a.i

a.i.

[Maximum mark: 2]

18M.2.hl.TZ1.1a.i

Urea, (H₂N)₂CO, is excreted by mammals and can be used as a fertilizer.

(a.i)

Calculate the percentage by mass of nitrogen in urea to two decimal places using section 6 of the data booklet.

[2]

Markscheme

molar mass of urea «4 $\times$ 1.01 + 2 $\times$ 14.01 + 12.01 + 16.00» = 60.07 «g mol^_-1»

«% nitrogen = $\frac{{{\text{2}} \times {\text{14.01}}}}{{{\text{60.07}}}}$ $\times$ 100 =» 46.65 «%»

Award [2] for correct final answer.

Award [1 max] for final answer not to two decimal places.

[2 marks]

Syllabus sections