Question

$14g$ of $CO$ at $27^{\circ }C$ is mixed with $16g$ 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 $=\frac{f_1}{2}R{T}_{CO}+\frac{f_2}{2}R{T}_{O_2}$
$=\frac{5}{2}R300+\frac{5}{2}R350$
$=\frac{5}{2}R(650)$
$=5R(325)$
$=1625R$
$1625=\frac{5}{2}R{T}_{\text{final }}\times n_{\text{final }}$
$\frac{1625\times 2}{5}=T_{\text{final }}\times n_{\text{final }}$
$325\times 2=T_{\text{final }}\times 2$
$T_{\text{frall }}=325K$
$T_{\text{finsl }}=37^{\circ }C$