I read that concave points in a Frost diagram disproportionate. But what are the products of the disproportionation?
For example, in the Frost diagram for manganese at pH = 0, the species $\ce{HMnO4-}$ is concave with respect to $\ce{MnO4-}$ and $\ce{H3MnO4}$. But at the same time, it is also concave with respect to $\ce{MnO4-}$ and $\ce{MnO2}$. How do I know which set of products $\ce{HMnO4-}$ disproportionates to in acidic solution at pH = 0?