Table 1. H₂O Is More Cohesive than H₂S, Despite Their Similar Structures, Because Water Forms Hydrogen Bonds.

property	H2O	H2S
molar mass [g mol–1]	18.015	34.081
boiling pointa [K]	373.12	212.85
melting pointa [K]	273.15	187.45
enthalpy of vaporizationb [kJ mol–1]	40.657	18.622
entropy of vaporizationb [J mol–1 K–1]	108.95	87.9
critical temperature [K]	647.1	373.2
critical pressure [MPa]	22.06	8.94
critical molar volume [cm3 mol–1]	55.9	98.5
critical density [kg m–3]	322	347
critical compressibility	0.229	0.284
specific heat capacityc (CV) [J mol–1 K–1]	74.539	26
specific heat capacityc (Cp) [J mol–1 K–1]	75.3	34.6

^aAt 101.3 kPa.

^bAt boiling.

^cAt 25 °C and 101.3 kPa.