Question

An ideal gas has molar specific heat $5\,R/2 $ at constant pressure. If $300\, J$ of heat is given to two moles of gas at constant pressure, the change in temperature is

• A. $ 7.22^{\circ }C $
• B. $ 8.94^{\circ }C $
• C. zero
• D. $ 5^{\circ} C $

Answer 1

Answer: (A)

The heat required at constant pressure
$Q=n C_{p} \Delta T$
$\therefore $ Change in temperature
$\Delta T=\frac{Q}{n C_{p}}$
Here: $Q=300 J, n=2$ mole $C_{p}=\frac{5}{2} R$
$R,$ the gas constant
$=8.31 \,J\, m o l^{-1}\, K ^{-1} $
$\therefore \Delta T=\frac{300}{2 \times \frac{5}{2} \times 8.31} $
$=\frac{300}{5 \times 8.31}=7.22^{\circ} C$