https://doi.org/10.1351/goldbook.Z06751
This hypothesis states that, if in an acid catalysed reaction, \(\log _{10}k_{1}\) (first-order @[email protected] of the reaction) is linear in \(H_{0}\) (Hammett @[email protected]), water is not involved in the @[email protected] of the @[email protected] However, if \(\log _{10}k_{1}\) is linear in \(\log _{10}\left[\text{H}^{+}\right]\) then water is involved. This has been shown to be incorrect by Hammett himself.