A closed box of fixed volume 0.15 m³ contains 3.0 mol of an ideal monatomic gas. The temperature of the gas is 290 K.

Question

SLPaper 2

Calculate the pressure of the gas.

[1]

Verified

Solution

«( $\frac{3.0 \times 8.31 \times 290}{0.15} »$ 48 «kPa» $\checkmark$

When the gas is supplied with 0.86 kJ of energy, its temperature increases by 23 K. The specific heat capacity of the gas is 3.1 kJ kg⁻¹ K⁻¹. Calculate, in kg, the mass of the gas.

[1]

Verified

Solution

mass $=$ « $\frac{860}{3100 \times 23}=» 0.012 \, kg$ 1 mark

Calculate the average kinetic energy of the particles of the gas.

[1]

Verified

Solution

$\frac{3}{2} 1.38 \times 10^{-23} \times 313=6.5 \times 10^{-21}$ «J» 1 mark

Explain, with reference to the kinetic model of an ideal gas, how an increase in temperature of the gas leads to an increase in pressure.

[3]

Verified

Solution

larger temperature implies larger (average) speed/larger (average) KE of molecules/particles/atoms 1 mark
increased force/momentum transferred to walls (per collision) / more frequent collisions with walls 1 mark
increased force leads to increased pressure because P=F/A (as area remains constant) 1 mark