Question

A gas occupies a volume of $2L$ at STP. It is provided with $58.65J$ of heat so that its volume becomes $2.5L$ at $1atm$. Calculate the change in its internal energy. $(Take1atm.L=101.3J)$

• A. $8J$
• B. $50.65J$
• C. $58.65J$
• D. $80J$

Answer 1

The correct option is A $8J$

Work done $=-P\times △V=-1\times (2.5-2.0)$
$=-0.5Latm$
Converting to joule,
$-0.5\times 101.3=-50.65J$
From the first law of thermodynamics,
$Q=△U-W$
$58.65=△U+50.65$
$\therefore △U=8J$