DP Physics (last assessment 2024)

Question 21N.2.HL.TZ0.d.ii

d.ii.

[Maximum mark: 2]

21N.2.HL.TZ0.d.ii

The molar mass of nitrogen is 28 g mol⁻¹.

Estimate the root mean square speed of nitrogen molecules in the Titan atmosphere. Assume an atmosphere temperature of 90 K.

[2]

Markscheme

$« \frac{1}{2} m v^{2} = \frac{3}{2} k T \Rightarrow » v = \sqrt{\frac{3 k T}{m}}$ ✓

$v = « \sqrt{\frac{3 \times 1.38 \times 10^{- 23} \times 90}{4.651 \times 10^{- 26}}} = » 283 \approx 300$ «ms⁻¹» ✓

Award [2] marks for a bald correct answer.

Allow 282 from a rounded mass.

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