This lecture covers the quantification of temperature changes and heat exchange in gases, focusing on the specific heat capacity at constant volume. It explains the mathematical complements on differentials of a function of several variables, the concept of conservative quantities like heat and work, and the relationship between heat exchanged and temperature change. The lecture also discusses the specific heat capacities of various substances and the energy internal of ideal gases. The instructor introduces the concept of degrees of freedom in the context of energy storage and explains the energy internal for monoatomic and diatomic perfect gases.