Question

Three moles of an ideal gas are expanded isothermally from a volume of 300 cm³ to 2.5 L at 300 K against a pressure of 1.9 atm. The work done in joules is ____________.

Options

• - 423.56 J

• + 423.56 J

• - 4.18 J

• + 4.8 J

Answer 1

Three moles of an ideal gas are expanded isothermally from a volume of 300 cm³ to 2.5 L at 300 K against a pressure of 1.9 atm. The work done in joules is - 423.56 J.

Explanation:

Given,

V₁ = 300 cm³ = 3 × 10^-4 m³ 

V₂ = 2.5 L = 25 × 10^-4 m³ 

T = 300 K

p = 1.9 atm = 1.9 × 1.01325 × 10⁵ N/m²

Now, work done during the change in volume against constant pressure is

W = - p(V₂ - V₁)

= - 1.9 × 1.01325 × 10⁵ N/m² (25 × 10^-4 - 3 × 10^-4)m³

= - 1.925 × 10⁵(22 × 10^-4) Nm

= - 423.56 Nm ...(∵ 1 Nm = 1 J)

= - 423.56 J