text: Arthur Frost stated in his own original publication that there may be potential criticism for his Frost diagram. He predicts that “the slopes may not be as easily or accurately recognized as they are the direct numerical values of the oxidation potentials [of the Latimer diagram]”. Many inorganic chemists use both the Latimer and Frost diagrams in tandem, using the Latimer for quantitative data, and then converting those data into a Frost diagram for visualization. Frost suggested that the numerical values of standard potentials could be added next to the slopes to provide supplemental information.
  In a paper published in the Journal of Chemical Education, Martinez de Ilarduya and Villafañe (1994) warn users of Frost diagrams to be aware of the definition of the free energy used to construct the diagrams. In acid-solution graphs, the standard nE° = −ΔG/F is universally used; therefore all sources’ acid-solution Frost diagrams will be identical. However, various textbooks show discrepancies in the Frost diagram of an element, in regards to the energy. Some textbooks use the reduction potential, E°(2  + 2 /H), defined in an acid-solution for a basic-solution. In the Phillips and Williams Inorganic Chemistry textbook, however, another reduction potential is used for the basic solutions given by the following formula: E°(OH) = E° − E°(2 HO + 2 /H + 2 OH) = E° + 0.828 V. This other way of presenting reduction potentials is used in some textbooks and not in others, but is not always explicitly indicated on the graph, creating confusion for the reader. So, users of the Frost diagram should be aware of the problem, and should always be clearly informed on which free-energy scale their diagrams are based.