Question

A system undergoes a process which absorbed 0.5 kJ of heat and undergoing an expansion against an external pressure of 1 atm, during the process change in internal energy is 300 J. Then predict the change in volume (lit.)

• A. $1$
• B. $2$
• C. $3$
• D. $4$

Answer 1

Answer: (B)

$2$

Solution:- (B) $2$

As we know that in the expansion of gas, work is done by the system.

$\therefore W=-P_{ext}\Delta V$

Given that:-

$P_{ext.}=1atm$

$\Delta V=?$

$\therefore W=-1\times \Delta V=-\Delta V\times 101.33J$

Given $q=+0.5kJ=500J$

$\Delta E=300J$

Now from first law of thermodynamics,

$\Delta E=q+w$

$300=500+(-\Delta V\times 101.3)$

$\Rightarrow \Delta V=\frac{200}{101.33}=1.97L\approx 2L$

Hence the change in volume will be $2L$.