Question

Calculate the constant external pressure required to expand 2 moles of an ideal gas from volume 15 dm³ to 20 dm³ if amount of work done is -600 J.

[Note: The question has been modified to get the correct answer.]

Options

• 1.2 bar

• 1.5 bar

• 1.8 bar

• 2.1 bar

Answer 1

1.2 bar

Explanation:

1 bar dm³ × 100 = J

V₁ = 15 dm³

V₂ = 20 dm³

W = −P_extΔV

\[\mathrm{P_{ext}}=-\frac{\mathrm{W}}{\Delta\mathrm{V}}=-\frac{\mathrm{W}}{\left(\mathrm{V_{2}}-\mathrm{V_{1}}\right)}\]

\[\mathrm{P_{ext}=-\frac{\left(-600\right)J}{\left(20-15\right)dm^{3}}=\frac{600J}{5dm^{3}}\times\frac{1dm^{3}bar}{100J}}\]

= 1.2 bar

[Note: In the question dm^-3 is changed to dm³ to apply appropriate textual concepts. |