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Question 21N.2.hl.TZ0.9b(iii)

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Date November 2021 Marks available [Maximum mark: 3] Reference code 21N.2.hl.TZ0.9b(iii)
Level hl Paper 2 Time zone TZ0
Command term Explain Question number b(iii) Adapted from N/A
b(iii).
[Maximum mark: 3]
21N.2.hl.TZ0.9b(iii)

Fast moving helium nuclei (4He2+) were fired at a thin piece of gold foil with most passing undeflected but a few deviating largely from their path. The diagram illustrates this historic experiment.

Figure from PPLATO / FLAP (Flexible Learning Approach To Physics), http://www.met.reading.ac.uk/pplato2/h-flap/
phys8_1.html#top 1996 The Open University and The University of Reading.

(b(iii))

Copper is a transition metal that forms different coloured complexes. A complex [Cu(H2O)6]2+ (aq) changes colour when excess Cl− (aq) is added.

Explain the cause of this colour change, using sections 3 and 15 from the data booklet.

[3]

Markscheme

chloride is lower in the spectrochemical series ✔

«ligand cause» decreased/lesser splitting «in d-orbitals compared to H2O» ✔


frequency/energy of light absorbed is decreased
OR
wavelength of light absorbed is increased ✔


Accept ·chloride a weaker ligand than water/produces a smaller energy difference than water for M1.

Award [2 max] for mentioning splitting of orbitals is changed AND frequency/ wavelength/energy of light absorbed
are different/changed without mentioning correct decrease or increase.

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