Question

$14\, g$ of $CO$ at $27^{\circ} C$ is mixed with $16\, g$ of $O _{2}$ at $47^{\circ} C$. The temperature of mixture is (vibration mode neglected)

• A. $-5^{\circ} C$
• B. $32^{\circ} C$
• C. $37^{\circ} C$
• D. $27^{\circ} C$

Answer 1

Answer: (C)

$1$ mole of $CO$ and $1$ mole of $O _{2}$ are mixed.
Net internal energy $=\frac{f_{1}}{2} R T_{ CO }+\frac{f_{2}}{2} R T_{ O _{2}}$
$=\frac{5}{2} R 300+\frac{5}{2} R 350$
$=\frac{5}{2} R(650) $
$=5 R(325) $
$=1625 \,R$
$1625=\frac{5}{2} R T_{\text {final }} \times n_{\text {final }}$
$\frac{1625 \times 2}{5}=T_{\text {final }} \times n_{\text {final }}$
$325 \times 2=T_{\text {final }} \times 2$
$T_{\text {frall }}=325 \,K$
$T_{\text {finsl }}=37^{\circ} C$