DP Chemistry (last assessment 2024)

Test builder »

Question 19N.2.hl.TZ0.e(ii)

Select a Test
Date November 2019 Marks available [Maximum mark: 2] Reference code 19N.2.hl.TZ0.e(ii)
Level hl Paper 2 Time zone TZ0
Command term Determine, Show Question number e(ii) Adapted from N/A
e(ii).
[Maximum mark: 2]
19N.2.hl.TZ0.e(ii)

The equations show steps in the formation and decomposition of ozone in the stratosphere, some of which absorb ultraviolet light.


Step 1    O2 → 2O•

Step 2    O• + O2 → O3

Step 3    O3 → O• + O2

Step 4    O• + O3 → 2O2

Determine, showing your working, the wavelength, in m, of ultraviolet light absorbed by a single molecule in one of these steps. Use sections 1, 2 and 11 of the data booklet.

[2]

Markscheme

ALTERNATIVE 1:
for oxygen:

E=«498 000 J mol−16.02×1023 mol−1=» 8.27×10−19 «J» ✔

λ = «6.63×10−34 J s×3.00×108 m s−18.27×10−19 J=» 2.40×10−7 «m»✔

 

ALTERNATIVE 2:
for ozone:

similar calculation using 200 < bond enthalpy < 400 for ozone, such as

E=«300 000 J mol−16.02×1023 mol−1=» 4.98×10−19«J» ✔

λ = «6.63×10−34 J s×3.00×108 m s−14.98×10−19 J=» 3.99×10−7 «m»✔

 

NOTE: Award [2] for correct final answer.

Syllabus sections