Achieve Homework #5

[405995505]

So, for #5 it says that you have to add the concentrations of BH and B to find the formal concentration. However, I am not so sure as to why we use the formal concentration instead of the initial concentration of B itself.

[Anita Sarransingh 2A]

This is because the formal concentration is the same as the initial concentration of B in this case. Since some of the B gets protonated to make BH, the amount of B in the solution has decreased by the time the solution reaches equilibrium. To find the initial concentration, the equilibrium concentration of B and the protonated concentration of B, or BH, must be added together, and this will represent the amount of B that was present before any protonation began.