DP Chemistry (first assessment 2025)

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Question 19M.2.SL.TZ1.4a

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Date May 2019 Marks available [Maximum mark: 2] Reference code 19M.2.SL.TZ1.4a
Level SL Paper 2 Time zone TZ1
Command term Outline Question number a Adapted from N/A
a.
[Maximum mark: 2]
19M.2.SL.TZ1.4a
(a)

Outline two differences between heterogeneous and homogeneous catalysts.

[2]

Markscheme

Any two of:
heterogeneous catalyst is in different phase than reactants AND homogeneous catalyst in same phase   [✔]

homogeneous catalysts chemically change/react and reformed at end of reaction
OR
reactants adsorb onto heterogenous catalyst and products desorb    [✔]

heterogeneous catalysts are more easily removed than homogenous catalysts     [✔]

heterogeneous catalysts can function at higher temperatures     [✔]

homogeneous catalysts are «generally» more selective     [✔]

homogeneous catalysts offer a broader range of reactions     [✔]

 

Note: Accept “state” for “phase”.

Accept “heterogeneous catalyst provides a surface to activate reaction”.

 

Examiners report

Most candidates correctly stated one difference between heterogeneous and homogeneous catalysts. Few gave a second difference even though the question is worth 2 marks.

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