And because this final bond is lower in energy than either of these two atomic orbitals, we release energy and we release our energy. Change in enthalpy. So change in energy simply change in enthalpy. So, as our reaction progresses, our energy drops by this amount, and it's actually 900 kilogows per mole. In other words, if we have 1 mol of methyl radical reaction with 1 mol of methyl radical, we form 1 mol of essay and we release energy. So we release 90 energy.