This lecture covers the principles of acid-base equilibrium, including the pH scale, dissociation of strong and weak acids, and the construction of pH and pOH diagrams. It also discusses the behavior of strong and weak bases, the autoprotolysis of water, and the concepts of conjugate acid-base pairs. The instructor explains the calculation of pH for different acid and base solutions, the relationship between acid strength and dissociation, and the importance of equilibrium constants. The lecture concludes with a summary of key concepts and practical applications in determining solution pH.