Question

When 1 mole of ice melts at $0^{0}C$ and at constant pressure of 1 atm. 1440 calories of heat are absorbed by the system. The molar volumes of ice and water are 0.0196 and 0.0180 litre respectively. Calculate $\Delta H$ and $\Delta E$ for the reaction.

Answer 1

Since heat is absorbed here at constant pressure so $\Delta H=1440$ calories
$\Delta U$ can be calculated by using the formula $\Delta U=\Delta H-P\Delta V$
$P=1atm$, $\Delta V=0.0196L-0.180L=0.0016L$
P $\Delta V=1\ast 0.0016=0.0016Latm=0.0016\ast 24.217$calories. ($1Latm=24.217$ calories)
So $\Delta U=1440cal-0.0016\ast 24.217cal\approx 1439.96$calories .There is negligible work done here.
so you can write $\Delta H\approx \Delta U.$