DP Chemistry (last assessment 2024)

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Question 19M.3.hl.TZ2.18a

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Date May 2019 Marks available [Maximum mark: 2] Reference code 19M.3.hl.TZ2.18a
Level hl Paper 3 Time zone TZ2
Command term Describe Question number a Adapted from N/A
a.
[Maximum mark: 2]
19M.3.hl.TZ2.18a

This question is about global warming.

(a)

Describe the effect of infrared (IR) radiation on carbon dioxide molecules.

[2]

Markscheme

bond length/C=O distance changes
OR
«asymmetric» stretching «of bonds»
OR
bond angle/OCO changes [✔]

polarity/dipole «moment» changes
OR
dipole «moment» created «when molecule absorbs IR» [✔]

 

Note: Accept appropriate diagrams.

Examiners report

This part was fairly well answered with most candidates receiving one of the two marks. There were many candidates who stated asymmetric stretching and bonds vibrate but missed writing polarity and dipole changes, which deprived them of the second mark.

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