Question

If a gas expands adiabatically from 1.0 L to 12.0 L against a constant pressure of 0.75 atm, the $\Delta U$ of the gas is

• A. -853.9 J
• B. 835.9 J
• C. 853.9 J
• D. -835.9 J

Answer 1

The correct option is D -835.9 J

$\Delta U=q+w$
$q=0$, for adiabatic process.
$w=-P\Delta V$
$=-0.75(12-1)$ atm L
$=-\frac{3}{4}\times 11$ atm L
$=-8.25$ atm L
$=-8.25\times 101.325$ J
$=-835.93J$

Option D is correct.