Question

A gas occupies $2litre$ at STP. It is provided with $58.63J$ of heat so that its volume becomes $2.5litre$ at $1atm$. Calculate the change in its internal energy (in $J$).

• A. 8.6
• B. 10
• C. 15.8
• D. 11.5

Answer 1

The correct option is A 8.6

Work done$=-P\times \Delta V=1\times (2.5-2.0)$
$=0.5litre.atm$
$=0.5\times {10}^{-3}{m}^3\times {10}^{5}Pa$
$=-50J$

From the first law of thermodynamics,
$△U=q+w$
$△U=58.63-50$
$\therefore △U=8.63J$