# Physics Homework Help !?

0.17 mol of argon gas is admitted to an evacuated 80 cm3 container at 20 ∘ C. The gas then undergoes an isothermal expansion to a volume of 400 cm3 .

What is the final pressure of the gas?

### 1 Answer

- billrussell42Lv 73 weeks ago
assuming that is 80 cm³

80 cm³ = 80 mL = 0.08 L

400 cm³ = 400 mL = 0.4 L

20ºC = 293.16 K

initial

P = nRT/V = (0.17)(0.08206)(293.16) / (0.08) = _____ atm

final

P₂ = P₁V₁/V₂ = [ (0.17)(0.08206)(293.16) / (0.08) ] [ (0.08/0.4 ]

P₂ = (0.17)(0.08206)(293.16) / (0.4) = _____ atm

but we could have just plugged 0.4 L into the first equation.

Constant temperature (Boyle's law)

P₁V₁ = P₂V₂

P₂ = P₁V₁/V₂

V₂ = P₁V₁/P₂

Ideal gas law

PV = nRT

n = number of moles

R = gas constant = 0.08206 (atm∙L)/(mol∙K)

8.314 L∙kPa/mol∙K

0.08314 L∙bar/mol∙K

62.36 L∙torr/mol∙K

62.36 L∙mmHg/mol∙K

T = temperature in kelvins

P = absolute pressure in atm, kPa, bar, torr

V = volume in liters