Thermodynamic analysis via simultaneous equations of previously reported mass spectra obtained from water vapor at 99 degreesC yielded DeltaE, DeltaH, and DeltaV values for H-bond formation in large, ion-induced, charged, water clusters, H+(H2O)(c), ranging from C approximate to 20 to C approximate to 45 H2O. An average DeltaE value of -2190 +/- 15 cal/mol H-bond was calculated for formation at pressures from approximate to0.39 to approximate to0.56 bar, as well as an approximate DeltaH of -2540 +/- 70 cal/mol H-bond. However, van't Hoff treatment of mass spectral data between 41 and 90 degreesC at a constant partial pressure of 0.038 bar yielded a more accurate DeltaH of -2425 +/- 25 cal/mol H-bond. Both DeltaH's are in close agreement with H-bond DeltaH's from Raman, infrared, and viscosity data for liquid water, despite the fact that they refer to charged water clusters. A DeltaV value of -31 300 +/-1000 cm(3)/Mol H-bond also resulted from the simultaneous equations. This DeltaV compares favorably with a limiting DeltaV value of -30 790 cm(3)/Mol H-bond corresponding to the condensation of steam to liquid water at 0.5 bar and 373.15 K. The DeltaE, DeltaH, DeltaV, and DeltaS values involved here demonstrate that the condensation of monomeric water onto large, charged, clusters in the vapor is analogous to the condensation of steam.