Question

The molar specific heat of oxygen at constant pressure $C_p=7.03cal/mo{l}^{\circ }C$ and $R=8.31J/mo{l}^{\circ }C$. The amount of heat taken by $5mol$ of oxygen when heated at constant volume from ${10}^{\circ }C$ to ${20}^{\circ }C$ will be approximately

• A. $25cal$
• B. $50cal$
• C. $250cal$
• D. $500cal$

Answer 1

The correct option is C $250cal$

The value of R in caloric system is 2
Thus, using
$C_v=C_p-R$

Thus, $C_v=7.03-2$
So,

$C_v=5.03$

Now,
amount of heat required will be
Q = U = $n{C}_v\Delta T$
Q = $5\times 5.03\times 10$
$Q\approx 250cal$