Work diagram for plutonium

Predominance region diagrams, as guides to the chemistries of elements in solutions, are described, with reference to the potential-pH diagram. A description is now given of free energy-pH diagrams (referred to as work diagrams). A work diagram for aqueous plutonium is presented, showing how much work must be expended upon one liter of a solution containing one millimole of plutonium, initially in the trivalent state, in order to convert it into some other oxidation state distribution in which another oxidation state predominates. Methods of preparing the diagram, and the thermodynamics involved, are discussed. (U.K.)