This lecture covers the statement of the first principle of thermodynamics, which expresses the conservation of energy in a thermodynamic system during processes involving heat and work exchange. It also discusses the generalization of the concept of work, the applications of the first principle, and the adiabatic transformation of a perfect gas. The lecture further explores the specific heat of a perfect gas, the relationship between pressure, volume, and temperature, and the distinction between reversible and irreversible transformations in thermodynamics.