Physics 9702 · AS & A Level · Equation of state

Equation of state — practice question

The ideal-gas equation of state can be written as $pV = NkT$.
(a(i))[3]

State what each symbol in this equation represents: $p$, $V$, $N$, $k$, $T$.

(a(ii))[2]

Using the equation of state, derive an expression for the mean translational kinetic energy $E_K$ of a particle in the gas in terms of some or all of $N$, $k$ and $T$.

(b)[2]

A hydrogen gas molecule contains two hydrogen atoms, each with nucleon number 1. An oxygen gas molecule contains two oxygen atoms, each with nucleon number 16. Suppose hydrogen and oxygen both act as ideal gases. A sample of hydrogen gas is at the same temperature as a sample of oxygen gas. For these two samples, find the ratio $\dfrac{\text{root-mean-square (r.m.s.) speed of hydrogen molecules}}{\text{root-mean-square (r.m.s.) speed of oxygen molecules}}$.

Worked solution & mark scheme

This 7-mark question has a full step-by-step worked solution and mark scheme. One marking point: $p$ = pressure of the gas, $V$ = gas volume and $k$ = Boltzmann constant

  • Full mark scheme, point by point
  • Step-by-step worked solution
  • Write your answer & get it marked instantly by AI