Buffer Solutions Calculator

A comprehensive tool for calculating buffer solution pH and composition using the Henderson-Hasselbalch equation. Determine pH for a given buffer, find required acid/base ratios for target pH, and analyze buffer capacity.

Buffer Solutions Calculator

Use this tool to calculate buffer solution properties using the Henderson-Hasselbalch equation:

pH = pKa + log((base) / (acid))

Where:

  • pKa: Negative logarithm of the acid dissociation constant
  • base: Concentration of the conjugate base or salt (A⁻)
  • acid: Concentration of the weak acid (HA)

Key Concepts

  • The best buffering effect is achieved when the (A⁻)/(HA) ratio is 1 (pH = pKa)
  • Buffer capacity depends on the magnitude of both [A⁻] and [HA] concentrations
  • Choose an acid/base with pKa closest to your target pH
Calculator

Inputs

Results

pH--
Base/Acid Ratio--
pOH--
Calculator

Inputs

Results

Required [Base]/[Acid] Ratio--
Required Base Concentration-- M
pH vs pKa Difference--
AcidpKaBest For pH RangeUse Case
Chloroacetic Acid2.872.5 - 3.5Very acidic buffers
Formic Acid (HCOOH)3.743.3 - 4.3Acidic buffers
Ethanoic Acid (CH₃COOH)4.764.3 - 5.3Weak acid buffers
Benzoic Acid4.203.7 - 4.7Moderate acidic buffers
Propanoic Acid4.874.4 - 5.4Weak acid buffers
Ammonia (NH₃)9.248.7 - 9.7Basic buffers
Hypochlorous Acid7.547.0 - 8.0Neutral to weak basic buffers
Buffer TypeInitial pHAfter 0.20 mol HCl AddedpH ChangeBuffer Capacity
7.00 M CH₃COOH / 7.00 M CH₃COONa4.764.760.00High
0.070 M CH₃COOH / 0.070 M CH₃COONa4.764.500.26Low