Question

Two moles of an ideal gas (C_v = 12.5 J K^–1mol^–1) occupy a volume of 2 dm³ at 300 K. If it is heated to 320 K to increase the volume to 4 dm³ the entropy change is –

• A. 11.5
• B. 8.3
• C. 13.1
• D. 9.3

Answer 1

Answer: (C)

13.1

Answer 2

DS = n C_v In $\frac{T_{2}}{T_{1}}$ + nR In $\frac{V_{2}}{V_{1}}$

= 2 × 12.5 × 2.303 log $\frac{320}{300}$ (2 × 8.314 × 2.303 log $\frac{4}{2}$)

= 1.6 + 11.5 = 13.1 J K^–1 mol^–1