A gas is contained inside a sealed syringe, as shown.

Question 23

A gas is contained inside a sealed syringe, as shown.

The volume of gas at room temperature is 2.0 cm³.

Atmospheric pressure is 101 kPa.

What is the work done by the gas when it is heated and expands to a volume of 6.0 cm³?

A 404 μJ                    B 404 mJ                    C 404 J                       D 404 kJ

Reference: Past Exam Paper – November 2015 Paper 11 Q15

Solution:

Answer: B.

At constant pressure p,

Work done by gas = p ΔV

where ΔV is the change in volume

Initial volume = 2.0 cm³

Final volume = 6.0 cm³

ΔV = 6.0 – 2.0 = 4.0 cm³

1 cm³ = 1 cm × 1 cm × 1 cm

1 cm³ = 0.01 m × 0.01 m × 0.01 m = 10^-6 m

Work done by gas = p ΔV

Work done by gas = 101 000 × (4.0×10^-6)

Work done by gas = 404×10^-3 J

 
Work done by gas = 404 mJ