The enthalpy of formation of (g) from the following reaction: (g) + (g) -> 2(g) + 44 kcal is — Thermodynamics and Thermochemistry Chemistry Question

💡 Solution & Explanation

The given thermochemical reaction shows that 44 kcal of heat is released (exothermic) when 2 moles of $HCl$(g) are formed: $H_2$(g) + $Cl_2$(g) -> 2$HCl$(g), δ H = -44 kcal. The standard enthalpy of formation is defined per mole of substance formed, so delta_f H°($HCl$, g) = -44 / 2 = -22 kcal/mol.