Công thức tính biến thiên enthalpy chuẩn của phản ứng theo nhiệ thành là

$\Delta {}_{\text{r}}\text{H}{}_{298}^0=\Sigma \Delta {}_{\text{f}}\text{H}{}_{298}^0( \text{c}\text{d})-\Sigma \Delta {}_{\text{f}}\text{H}{}_{298}^0(\text{s}\text{p})$.

$\Delta {}_{\text{r}}\text{H}{}_{298}^0=\Sigma \Delta {}_{\text{f}}\text{H}{}_{298}^0(\text{s}\text{p})-\Sigma \Delta {}_{\text{f}}\text{H}{}_{298}^0( \text{c}\text{d})$.

$\Delta {}_{\text{r}}\text{H}{}_{298}^0=\Sigma \text{E}{}_{\text{b}}(\text{c}\text{d})-\Sigma \text{E}{}_{\text{b}}(\text{s}\text{p})$.

$\Delta {}_{\text{r}}\text{H}{}_{298}^0=\Sigma \text{E}{}_{\text{b}}(\text{s}\text{p})-\Sigma \text{E}{}_{\text{b}}(\text{c}\text{d})$.