The heat change for the following reaction $\mathrm{C}\left(\mathrm{s}\right)+2\mathrm{S}\left(\mathrm{s}\right)\to {\mathrm{CS}}_2\left(\mathrm{l}\right)$ known as

The standard Heat of formation is defined as amount of heat absorbed or evolved when one mole of the substance is formed from its constituent elements at 1 and pressure and 298 K temperature. 

Example: $\mathrm{C}\left(\mathrm{s}\right)+2\mathrm{S}\left(\mathrm{s}\right)\to {\mathrm{CS}}_2\left(\mathrm{l}\right)$