DP Chemistry (last assessment 2024)

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Question 17N.3.hl.TZ0.8b.i

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Date November 2017 Marks available [Maximum mark: 1] Reference code 17N.3.hl.TZ0.8b.i
Level hl Paper 3 Time zone TZ0
Command term Determine Question number b.i Adapted from N/A
b.i.
[Maximum mark: 1]
17N.3.hl.TZ0.8b.i

Metals have various crystal structures. Cobalt forms a face-centred cubic (FCC) lattice. Two representations of FCC are shown.

(b.i)

The atomic radius, r, of cobalt is 1.18 × 10–8 cm. Determine the edge length, in cm, of the unit cell, a, using the second diagram.

[1]

Markscheme

face diagonal  = 2 a = 4 r

« a = ( 4 × 1.18 × 10 − 8 cm ) 2 = » 3.34 x 10–8 «cm»

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