Question

Under isothermal conditions, a gas at 300 K expands from 0.1 L to 0.25 L against a constant external pressure of 2 bar. The work done by the gas is:
(Given that 1 L bar = 100 J)

• A. -30 J
• B. 5 kJ
• C. 25 J
• D. 30 J

Answer 1

The correct option is A -30 J

$W_{irr}=-P_{\mathrm{ext}}\Delta V$
= – 2 bar × (0.25 – 0.1) L
= – 2 × 0.15 L-bar
= – 0.30 L-bar
= – 0.30 × 100 J
= – 30 J