DP Chemistry (last assessment 2024)

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Question 19M.3.sl.TZ2.13b

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Date May 2019 Marks available [Maximum mark: 2] Reference code 19M.3.sl.TZ2.13b
Level sl Paper 3 Time zone TZ2
Command term Describe Question number b Adapted from N/A
b.
[Maximum mark: 2]
19M.3.sl.TZ2.13b

This question is about global warming.

(b)

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 question was fairly well answered with most students receiving one of the two marks. There were many students who mentioned the information in M1 (asymmetric stretching and bonds vibrate) or M2 (polarity and dipole changes) more than one time but could only receive one mark. Teachers need to remind students each mark is a different topic or concept.

Syllabus sections