DP Chemistry (last assessment 2024)

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Question 20N.3.hl.TZ0.12f

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Date November 2020 Marks available [Maximum mark: 3] Reference code 20N.3.hl.TZ0.12f
Level hl Paper 3 Time zone TZ0
Command term Determine Question number f Adapted from N/A
f.
[Maximum mark: 3]
20N.3.hl.TZ0.12f

1.57 % of the mass of a rock weighing 46.5 kg is uranium(IV) oxide, UO2. 99.28 % of the uranium atoms in the rock are uranium-238, U238.

(f)

Determine the nuclear binding energy, in J, of U238 using sections 2 and 4 of the data booklet.

The mass of the U238 nucleus is 238.050786 amu.

[3]

Markscheme

238.050786«amu»×1.66×10−27«kg amu−1»
OR

 ✔

92×1.672622×10−27+146×1.674927×10−27−3.95×10−25
OR
3.42×10−27/3×10−27«kg» ✔

«E=mc2=3.42×10−27×(3.00×108)2=»3.08×10−10«J» ✔


Accept answers in the range “2.7×10−10–3.1×10−10«J»”.

Award [3] for correct final answer.

Examiners report

This demanding question on the determination of the nuclear binding energy was well executed and many scored all three marks. Even the weaker candidates still managed to gain an ECF mark for M3 by using the E = mc2 equation. The general performance on this type of calculation was much better than in previous sessions.

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