The composition of the saturated vapor and enthalpies of dimerization of rubidium and cesium pivalates

The rubidium and cesium pivalates sublimation processes are studied through the Knudsen effusion method with the mass-spectral analysis of the gaseous phase composition. It is established that MPiv and M2Piv2 and in small amounts M3Piv3 and M4Piv4 constitute the basic components in the saturated vapour of the rubidium and cesium pivalates. Sublimation enthalpies (kJ/mole) of monomers ΔSHT0=163.5±7.2 and dimers ΔSHT0(Cs2Piv2)-192.1±9.6 are determined. Dissociation enthalpies (kJ/mole) of the M2Piv2 dimers by the second(2) and the third (3) laws of thermodynamics: ΔDHT0(Cs2Piv2)=137.1±5.4(2), ΔDHT0(Rb2Piv2)=138.2±10.2 (3); ΔDHT0(Cs2Piv2)-134.9±9.3 (2), ΔDHT0(Cs2Piv2)=136.8±10.8 (3) are calculated. Temperature dependence equations (210-300 deg C of partial pressures (Pa) of the MPiv, M2Piv2 molecules: InP(RbPiv)=-(20099±674)/T+34.6±1.2; InP(Rb2Piv2)=-(23707±734)/T+40.4±1.4; InP(CsPiv)=-(19666±866)/T+34.1±1.6; InP(Cs2Piv2)=-(23106±1155)/T+39.5±2.1 are obtained