So- the way the starting material is plugged into this equilibrium equation is dependent on whether or not it is a strong acid or weak acid (just to use acids as an example). For a strong acid, dissociation is nearly complete (if not totally complete) and the equilibrium of the reaction will shift toward the water/H+ product. So 1.0 moles of starting material will give 1 mole of each H+ and H20. (based on molar ratios of 1: and assuming 1 is the limiting reactant)
If the acid is weak, the equilibrium of the reaction will stay shifted toward the reactant. In this case, we use 1.0 moles of HA - X as the value of how much HA will be left at equilibrium. Because X is extremely small, HA will remain essentially at 1.0 for the purposes of the equilibrium equation. The other side of the equation will be represented by x (a very small number) in equal amounts for both products. Therefore, it will be x2 (superscript) and you have to solve a math equation (square root of both sides).
Include this in the concept of buffers and other more complicated acid/base problems and it gets really, really confusing on when you are making what assumption if you don't really understand the concept of acid/base equilibrium.
Has anybody taught this and have any advice for me on teaching it?