Why is the Henderson Hasselbalch equation necessary for calculating the pH of weak acid solutions?

• A. Weak acids do not completely dissociate, requiring the equation to account for equilibrium concentrations.
• B. The equation is used to calculate the pKa of strong acids.
• C. The equation is only used for strong acids.
• D. Weak acids completely dissociate, making the equation unnecessary.

Answer: (A)