IB Physics HL B.3.7 Ideal gas internal energy Question Bank

Practise IB Physics HL B.3.7 by analysing monatomic-gas internal energy, particle kinetic energy and temperature-dependent state changes.

Exam points

Relate total particle kinetic energy to nRT, NkT and the gradient of an internal-energy graph.
Distinguish ideal-gas kinetic energy from real-gas intermolecular potential energy in comparisons.

[Maximum number: 2]

An ideal monatomic gas is kept in a container of volume $2.1 \times 10^{-4} \mathrm{~m}^{3}$ , temperature 310 K and pressure $5.3 \times 10^{5} \mathrm{~Pa}$ .

Calculate, in J , the internal energy of the gas.

«For one atom $U=\frac{3}{2} k T$ » $\underset{2}{\stackrel{3}{\text { 豊 }} \cdot 1^{2}} 1.38^{\cdot} 10^{-23} \cdot 310 / 6.4^{\cdot} 10^{-21}$ «J»
$U=\ll 2.6 \times 10^{22} \times \frac{3}{2} \times 1.38 \times 10^{-23} \times 310 \gg 170<\mathrm{J} \gg q$

Marking guidance:

Allow ECF from (a)(ii) Award [2] for a bald correct answer

Allow use of $U=\frac{3}{2} p V$

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B.3.7—Ideal gas internal energy question 1