DP Chemistry (last assessment 2024)

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

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Date May 2018 Marks available [Maximum mark: 1] Reference code 18M.2.hl.TZ1.1i
Level hl Paper 2 Time zone TZ1
Command term Suggest Question number i Adapted from N/A
i.
[Maximum mark: 1]
18M.2.hl.TZ1.1i

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

(i)

The C–N bonds in urea are shorter than might be expected for a single C–N bond. Suggest, in terms of electrons, how this could occur.

[1]

Markscheme

lone pairs on nitrogen atoms can be donated to/shared with C–N bond

OR

C–N bond partial double bond character

OR

delocalization «of electrons occurs across molecule»

OR

slight positive charge on C due to C=O polarity reduces C–N bond length

[1 mark]

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