Effect of metal ion on the reactivity of hydrogen-isotope exchange for monohydrogenphosphate.

A hydrogen-isotope exchange reaction between each of six monohydrogenphosphates and tritiated water vapor has been observed at 50-80°C. Following results were obtained after the activities observed in the solid samples were analyzed by using A′′-McKay and Arrhenius plots. 1. It is possible to compare the acidity of monohydrogenphosphates with each 9ther. 2. The acidity increases with increasing temperature. 3. Both the acidity of the compound and the temperature dependence of its reactivity increase when the electronegativity of a metal element in monohydrogenphosphate becomes large.