Question

Two mole of an ideal gas is heated at constant pressure of one atmosphere from 27⁰C to 127⁰C. If Cv,m = 20 + 10–2 T JK–1mol–1, then q and DU for the process are respectively :

• A. 6362.8 J, 4700 J
• B. 3037.2 J, 4700 J
• C. 7062.8, 5400 J
• D. 3181.4 J, 2350 J

Answer 1

Answer: (A)

6362.8 J, 4700 J

Answer 2

(1) w = – nR $\Delta$T = –2 × 8.314 × 100 = –1662.8 J

$\Delta$U = n $\int_{300}^{400}C_{V,m}$ dT = 2 × $\int_{300}^{400}{}$ (20 + 10–2 T) dT

= $3\left\lbrack 20 \times 100 + \frac{10^{- 2}}{2}\left( 400^{2} - 300^{2} \right) \right\rbrack$= 4700 J

4700 = q – 1662.8

$\therefore$ q = 6362.8 J.