Calculate the work for each of the following processes beginning with a gas sample in a piston assembly with T 5 305 K, P 5 1.79 atm, and V 5 4.29 L: (a) irreversible expansion against a constant external pressure of 1.00 atm to a final volume of 6.52 Lb) isothermal, reversible expansion to a final volume of 6.52 L.

Question

Kiera Barker

Chemistry

19 April, 00:11

Calculate the work for each of the following processes beginning with a gas sample in a piston assembly with T 5 305 K, P 5 1.79 atm, and V 5 4.29 L: (a) irreversible expansion against a constant external pressure of 1.00 atm to a final volume of 6.52 Lb) isothermal, reversible expansion to a final volume of 6.52 L.

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Answers (1)

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Broderick Ross · Answer 1

Answer: (a) W = - 2.23 J

(b) W = - 326J

Note: T = 305K; P = 1.79 atm; V = 4.29 L are the correct parameters

Explanation:

(A) using W = - Pex * ΔV

Pex = 1.00 atm, Vf = 6.52 L, Vi = 4.29 L

W = - 1.00 * (6.52 - 4.29) = ( - 1.00 * 2.23) J

W = - 2.23 J

(B) Using W = - nRTln (Vf/Vi)

R = 0.082 atmL/mol/K or 8.314 J/mol/K

T = 305 K

Vf = 6.52 L, Vi = 4.29 L

P = 1.79 atm

n = ?

Solving for n using PV = nRT

n = PV/RT

n = 1.79 * 4.29 / (0.082 * 305)

n = 0.3070418 moles

Solving for work done

W = - 0.3070418 * 8.314 * 305 * ln (6.52/4.29)

W = - 325. 906J

W = - 326J