# 2 Moles of Oxygen is heated from $0 ^{\circ} C$ at constant pressure till its volume increases by $20%$. The specific heat of Oxygen is given to be $0.22$ cal$\;g^{-1} K^{-1}$. What is the amount of heat required?

(A) 768 cal (B) 384 cal (C) 0 cal (D) 514 cal

$\Delta Q = m C \Delta T$, $\Delta u = nC_v \Delta T$ and $\Delta W = P \Delta V$
Now, at constant pressure P, $V \propto T \rightarrow \large\frac{\Delta T}{T}$$= 20\text{%}$
$\Rightarrow T_{\text{final}} = 327.5 ^{\circ} K \rightarrow \Delta T = 54.6 ^{\circ}$
Also, $m = 64\;g \rightarrow \Delta Q = 64 \times 0.22 \times 54.6 \approx 768\; \text{cal}$
answered Mar 11, 2014