Question

2.5 moles of an ideal gas are expanded isothermally from 12 dm³ to 25 dm³ against a pressure of 3.0 bar. Calculate the work obtained.

Answer 1

Given : 

n = 2.5 mol; 

V₁ = 12 dm³; 

V₂ = 25 dm³ 

P = 3.0 bar; 

W = ? 

W = -P_ext × (V₂ – V₁)

= – 3 × (25 – 12)

= -39 dm³ bar

∵ V₁ dm³ = 100 J

∴ W = -39 × 100 

= -3900 J 

= -3.9kJ