2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/102708Liquids with quasi - chemical bonding between molecules are described in terms of vertex model. It is shown that this bonding results in liquid - liquid phase transition, which occurs between phases with different mean density of intermolecular bonds. The transition may be suggested to be a universal phenomena for those liquids.12 pages, 3 figuresStatistical Mechanicstext