Write the formulas for both the weak acid and conjugate base

Write the formulas for both the weak acid and conjugate base used in the buffer. Write the dissociation reactions for each substance.

Na2CO3

NaHCO3

Solution

How to calculate the pH of a buffer solution containing both acid and conjugate base? Dissociation constant definition 1.1 can be rearranged into 15.1 or 15.2 (note that due to sign change [A-] was moved to nominator). This is so called Henderson-Hasselbalch equation (or a buffer equation). It can be used for pH calculation of a solution containing pair of acid and conjugate base - like HA/A-, HA-/A2- or B+/BOH. For solutions of a weak bases sometimes it is more convenient to use equation in the form 15.3