Question

A vessel contains 100 litres of a liquid $x$. Heat is supplied to the liquid in such a fashion that, Heat given = change in enthalpy. The volume of the liquid increases by 2 litres. If the external pressure is one atm, and 202.6 Joules of heat were supplied then, [ U - total internal energy ]

• A. $\Delta U=0,\Delta H=0$
• B. $\Delta U=+202.6J,\Delta H=+202.6J$
• C. $\Delta U=-202.6J,\Delta H=-202.6J$
• D. $\Delta U=0,\Delta H=+202.6J$

Answer 1

The correct option is D

$\Delta U=0,\Delta H=+202.6J$

$\Delta H$ = heat gives so process is isobaric.

$w=-P_{next}\left(\Delta V\right)=-1\times 2litre.atm=-202.6J$ -as one litre.atm=101.33 joules

Hence $q=202.6J=\Delta H$ and $\Delta E=q+w=0$