$1{\mathrm{LN}}_2\left(g\right)$ and $3{\mathrm{LH}}_2\left(g\right)$ at 1 bar pressure is allowed to react at constant pressure. The temperature of $100 \mathrm{gm}$ water surrounding reaction vessel rose by ${\left(\frac{1}{1.4}\right)}^{\circ }\mathrm{C}$. Find the magnitude of change in internal energy in joules for the process in reaction vessel. [Specific heat of ${\mathrm{H}}_2\mathrm{O}\left(l\right)=4.2\mathrm{J}{/}^{\circ }\mathrm{C}/\mathrm{g}$ litre atm $=100 \mathrm{J}$]