Could you please explain how the henderson helbach equation works?

The HH equation is useful for calculating the pH of buffer solutions, primarily, but there is some degree of uncertainty in the answer. That is because the HH equation "makes the umption". When we solve equilibrium problems we often ume that when a system reaches equilibrium that a small amount of the acid or base will react, such that there will be essentially no change in the concentration of the acid or base. i.e. suppose [acid] = 0.10M and x = 0.0001M, then subtracting 0.0001 from 0.10 will give 0.10.