Lawrence Joseph Henderson wrote an equation, in 1908, describing the use of carbonic acid as a buffer solution. Karl Albert Hasselbalch later re-expressed that formula in logarithmic terms, resulting in the Hendersonâ€“Hasselbalch equation.^{11,12} Hasselbalch was using the formula to study metabolic acidosis.
The Henderson-Hasselbalch equation (Equation 1) is used to calculate the pH of a system using the p*K*_{a} (logarithm of the acid dissociation constant *K*_{a}) of the acidic species in solution.Â It has many applications and can be used to determine the pH of a solution, calculate the molar ratio of acid and salt required to form a buffer of a particular pH, and give an estimate of the value of the p*K*_{a} of a species if the pH and concentration of the acid and salt components are known.
The Henderson-Hasselbalch equation is derived from the acid dissociation (*K*_{a}) constant as follows: |