The scope of limit equations and their role as starting points to deduce general equations are discussed. Consequently, a general strategy is proposed to go systematically from limit equations to general ones. On the basis of this strategy, the most common general equations in chemistry, like the equation of state for gases, the chemical potential of gases and the equation for the chemical equilibrium constant are illustrated. The method should help to emphasize students' need to think about the validity range of the equations they are learning and to illustrate the way science infers general equations from specific ones. Furthermore, it should allow explaining to students the several steps (introductory, medium and upper level) of their chemistry learning.