DP Chemistry (last assessment 2024)

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Question 22N.2.sl.TZ0.2e.iv

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Date November 2022 Marks available [Maximum mark: 1] Reference code 22N.2.sl.TZ0.2e.iv
Level sl Paper 2 Time zone TZ0
Command term Explain Question number e.iv Adapted from N/A
e.iv.
[Maximum mark: 1]
22N.2.sl.TZ0.2e.iv

Chloroquine is a medication used to prevent and treat malaria.

Chloroquine can be synthesized by reacting 4,7-dichloroquinoline with another reactant, B.

            4,7-dichloroquinoline                                                            chloroquine

(e.iv)

Explain, referring to the Maxwell–Boltzmann distribution curve, the effect of a catalyst on a chemical reaction.

[1]

Markscheme

increases rate AND there is a greater area under the curve past activation energy

OR

increases rate AND greater proportion of/more molecules have «kinetic» E ≥ Ea «(cat) than Ea (uncat)» ✔

 

Do not award a mark for general statements about catalysts such as “provides alternative pathway” or “lowers Ea”.

Examiners report

Most candidates identified that catalysts provided an alternative reaction pathway with a lower activation energy but most of them did not relate this to the Maxwell-Boltzmann distribution and hence did not gain the mark. Only 20% of the candidates were awarded the mark. A few candidates were confused and referred to an increase in the frequency of collisions when a catalyst is used.

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