DP Chemistry (last assessment 2024)

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Question 19M.3.hl.TZ1.16a(ii)

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Date May 2019 Marks available [Maximum mark: 1] Reference code 19M.3.hl.TZ1.16a(ii)
Level hl Paper 3 Time zone TZ1
Command term Outline Question number a(ii) Adapted from N/A
a(ii).
[Maximum mark: 1]
19M.3.hl.TZ1.16a(ii)

Uranium-235, 235U, is bombarded with a neutron causing a fission reaction.

Two products of the fission of 235U are 144Ba and 89Kr.

(a(ii))

Outline why the reaction releases energy.

[1]

Markscheme

greater binding energy per nucleon in products than reactants    [✔]

 

Note: Accept “mass of products less than mass of reactants” OR “mass converted to energy/E = mc2”.

Examiners report

Outlining why the fission reaction releases energy was challenging. Some candidates simply said the reaction was exothermic. Some said that the products were smaller than the reactant. Very few candidates referred to binding energy per nucleon.

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