Question

Calculate change in internal energy for 2 moles of an ideal gas that temperature rises from 27${}^{\circ }$ C to 127${}^{\circ }$ C. [ Given : Cp,m = 13.314 + 0.04 T ]

• A. 3800 J
• B. 1900 J
• C. 1028 J
• D. None of these

Answer 1

The correct option is A

3800 J

$C_{v.m}=Cp.m-R\Rightarrow (13.314-8.314)+0.04T$

$\Rightarrow 5+0.04T$

$△U=n.C_{v,m},△T$

$△U=(\underset{T_1}{\overset{T_2}{\int }}(5+0.04T))\times 2$

$△U=(5\left(△T\right)+0.04(\frac{T_2^2}{2}-\frac{T_1^2}{2}))\times 2$

= 3800 J