DP Chemistry (last assessment 2024)

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Question 19N.3.hl.TZ0.a(iii)

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Date November 2019 Marks available [Maximum mark: 3] Reference code 19N.3.hl.TZ0.a(iii)
Level hl Paper 3 Time zone TZ0
Command term Calculate Question number a(iii) Adapted from N/A
a(iii).
[Maximum mark: 3]
19N.3.hl.TZ0.a(iii)

Red supergiant stars contain carbon-12 formed by the fusion of helium-4 nuclei with beryllium-8 nuclei.

Mass of a helium-4 nucleus = 4.002602 amu
Mass of a beryllium-8 nucleus = 8.005305 amu
Mass of a carbon-12 nucleus = 12.000000 amu

Calculate the heat energy released, in J, by the fusion reaction producing one atom of carbon-12. Use section 2 of the data booklet and E = mc2.

[3]

Markscheme

Δm = «12.000000 amu − (4.002602 amu + 8.005305 amu) =» −0.007907 «amu» ✔
«0.007907 amu × 1.66 × 10−27 kg amu−1 =» 1.31 × 10−29 «kg» ✔
«E = mc2 = 1.31 × 10−29 kg × (3.00 × 108 m s−1)2 =» 1.18 × 10−12 «J» ✔

NOTE: Accept “0.007907 «amu»”.
Award [2 max] for “7.12 x 1014 «J»”.
Award [3] for correct final answer.

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