Weak Acid vs Strong Base · Charge Balance
Volume of the acid solution
Molar concentration of the acid
Molar concentration of the titrant (base)
Acid dissociation constant
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The inverse method (Charge Balance) iterates over pH values to compute the corresponding titrant volume, avoiding the numerical discontinuities of the direct method in the pH jump region.
For a weak monoprotic acid titrated with a strong base, the pH at the equivalence point is > 7 due to hydrolysis of the conjugate ion.
Henderson-Hasselbalch equation: At the half-equivalence point (½Veq), pH ≈ pKₐ. This zone is called the Buffer Region due to its high buffering capacity.
An indicator is suitable when its pKIn satisfies: |pKIn − pHeq| ≤ 1. The titration error is minimal when the indicator color change occurs within the pH jump of the curve.
Standard conditions: 25 °C, dilute aqueous solution, Kw = 10−14. Indicator source: Covington, A. K. — CRC Handbook of Chemistry and Physics.