Question

5 moles of oxygen is heated at constant volume from 10°C to 20°C. The change in the internal energy of the gas is (the gram molecular specific heat of oxygen at constant pressure, $C_{p} = 8$ cal/mole °C and R = 8.3 cal/mole °C)

• A. 200 cal
• B. 300 cal
• C. 100 cal
• D. None of these

Answer 1

Answer: (B)

300 cal

Answer 2

$\Delta U = nC_{V}\Delta T = n(C_{P} - R)\Delta T$

$= 5 \times \left( 8 - \frac{8.36}{4.18} \right) \times 10 = 5 \times 6 \times 10 = 300cal$