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Date November 2013 Marks available 2 Reference code 13N.2.HL.TZ0.4
Level Higher level Paper Paper 2 Time zone Time zone 0
Command term Determine Question number 4 Adapted from N/A

Question

This question is about an ideal gas.

Describe how the ideal gas constant R is defined.

[2]
a.

Calculate the temperature of 0.100 mol of an ideal gas kept in a cylinder of volume 1.40×10–3 m3 at a pressure of 2.32×105 Pa.

[1]
b.

The gas in (b) is kept in the cylinder by a freely moving piston. The gas is now heated at constant pressure until the volume occupied by the gas is 3.60×10–3 m3. The increase in internal energy of the gas is 760 J. Determine the thermal energy given to the gas.

[2]
c.

After heating, the gas is compressed rapidly to its original volume in (b). Outline why this compression approximates to an adiabatic change of state of the gas.

[2]
d.

Markscheme

defined from the equation of state of an ideal gas PV=nRT;
all symbols (PVnT) correctly identified;

a.

390/391 K;

b.

work done\( = \left( {P\Delta V = 2.32 \times {{10}^5} \times 2.20 \times {{10}^{ - 3}} = } \right)510{\rm{J}}\);
thermal energy\( = \left( {760 + 510 = } \right)1.27 \times {10^3}{\rm{J}}\);
Award [1 max] if volume is taken as 3.6×10–3, giving an answer of 1600 J.

c.

an adiabatic change is one in which no (thermal/heat) energy is transferred between system and surroundings / no energy enters/leaves system;
a rapid compression means that there is insufficient time (for energy transfer) / OWTTE;

d.

Examiners report

[N/A]
a.
[N/A]
b.
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c.
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d.

Syllabus sections

Option B: Engineering physics » Option B: Engineering physics (Core topics) » B.2 – Thermodynamics
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