User interface language: English | Español

Date May 2018 Marks available 3 Reference code 18M.2.HL.TZ1.2
Level Higher level Paper Paper 2 Time zone 1
Command term Determine Question number 2 Adapted from N/A

Question

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.

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.

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.

Determine, in kJ, the total kinetic energy of the particles of the gas.

[3]
b.ii.

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]
c.

Markscheme

ALTERNATIVE 1

average kinetic energy = 3 2 1.38 × 10–23 × 313 = 6.5 × 10–21 «J»

number of particles = 3.0 × 6.02 × 1023 = 1.8 × 1024

total kinetic energy = 1.8 × 1024 × 6.5 × 10–21 = 12 «kJ»

 

ALTERNATIVE 2

ideal gas so U = KE

KE 3 2 8.31 × 131 × 3

total kinetic energy = 12 «kJ»

 

[3 marks]

b.ii.

larger temperature implies larger (average) speed/larger (average) KE of molecules/particles/atoms

increased force/momentum transferred to walls (per collision) / more frequent collisions with walls

increased force leads to increased pressure because P = F/A (as area remains constant)

 

Ignore any mention of PV = nRT.

[3 marks]

c.

Examiners report

[N/A]
b.ii.
[N/A]
c.

Syllabus sections

Core » Topic 3: Thermal physics » 3.2 – Modelling a gas
Show 90 related questions
Core » Topic 3: Thermal physics
Core

View options