Acid dissociation constants of tetracyanohydroxooxomolybdate(IV) ion

Abstract

The third dissociation constant of tetracyanohydroxooxomolybdic acid, H₃[MoO(OH)(CN)₄], has been obtained in the temperature range 25-50°C from the pH-titration curve of its tripotassium salt against hydrochloric acid. The values of pK₃ fitted an equation of Harned- Robinson type:                      pK₃ = (1730.72/T)-6.19+0.0308T) obtained by the method of least squares.     Thermodynamic quantities ΔG°, ΔH°, ΔS°, and ΔC°_p for the process have been evaluated at 30°C.