The reaction of cyanamide ${\mathrm{NH}}_2\mathrm{CN}\left(\mathrm{s}\right)$ with oxygen was carried out in a bomb calorimeter and $∆{\mathrm{q}}_{\mathrm{v}}$ at 300 K was measured to be $-750 \mathrm{kJ}/\mathrm{mol}.$ The value of $∆\mathrm{H}$ per mole of ${\mathrm{NH}}_2\mathrm{CN}\left(\mathrm{s}\right)$ in the given reaction is