Question

$4.4\, g$ of an ideal gas $( mol . wt =44)$ at $300\, K$ and $10 atm$ is allowed is allowed to expand isothermally against a external pressure of $1 \,atm .$ Taking $1 \,L$ -atm $=100 \,J ,$ heat absorbed by the gas is:

• A. 200.5 J
• B. 212.5 J
• C. 221.4 J
• D. 242.4 J

Answer 1

Answer: (C)

$V_{i}=\frac{n R T}{P}=\frac{4.4}{44} \times \frac{0.082 \times 300}{10}$

$=0.246$ litre

$V _{ f }=\frac{ P _{1} V _{ i }}{ P _{ f }}$

$=\frac{10 \times 0.246}{1}=2.46$ litres

$q=-W=P\left(V_{f}-V_{i}\right)$

$=1(2.46-0.246) \times 100=221.4 J$