Universal Buffer Maker

1) Target Specs

Desired pH

pK_a of acid

Final volume

Total buffer concentration (acid + base), M

Tip: total concentration sets buffer capacity. For robust buffering, choose pH ≈ pK_a ± 1.

2) Reagents on Hand

Acid identity

Conjugate base source

Molar mass of acid (g/mol)

Density of liquid acid (g/mL)

Molar mass of KOH (g/mol)

Molar mass of salt (g/mol)

Leave defaults for acetic acid / potassium acetate. Adjust if using a different system.

3) Calculations

pH = pK_a + log₁₀([base]/[acid]) ⇒ ratio = 10^(pH − pK_a)
[acid] = C_total / (1 + ratio); [base] = C_total − [acid]
moles = concentration × volume (L)

4) Step-by-step Procedure

Important notes on buffer choice

Best buffering occurs when pH ≈ pK_a ± 1. Far outside this range, capacity is weak.
Typical pK_a: Acetic 4.74; Ammonium 9.25; Borate 9.24; Tris base 8.06 (25 °C).
Temperature affects pH/pK_a. Calibrate your pH meter and quote temperature.
When neutralizing strong base/acid, add slowly with stirring, cool if needed, and check pH after dilution to volume.