1. What is Buffer Capacity?

Buffer capacity (β) measures how well a solution resists changes in pH when acid or base is added. It's defined as the amount of strong acid or base needed to change the pH of 1 liter of solution by 1 unit.

2. How Does the Calculator Work?

The calculator uses the buffer capacity equation for weak acids:

Where:

• \( \beta \) — Buffer capacity (mol/L pH)
• \( C \) — Total buffer concentration (M)
• \( K_a \) — Acid dissociation constant (dimensionless)
• \( [H^+] \) — Hydrogen ion concentration (M)

Explanation: The equation shows buffer capacity depends on the total buffer concentration and the pH-dependent term that reaches maximum when pH = pKa.

3. Importance of Buffer Capacity

Details: Buffer capacity is crucial in biological systems (blood pH maintenance), chemical processes, and pharmaceutical formulations where stable pH is required.

4. Using the Calculator

Tips: Enter all values in proper units (C in molarity, [H+] in molarity). Ka is dimensionless. For best results, use values with appropriate precision (e.g., 1.75e-5 for acetic acid Ka).

5. Frequently Asked Questions (FAQ)

Q1: What is the maximum buffer capacity?
A: Maximum buffer capacity occurs when pH = pKa (when [H+] = Ka). At this point, β_max = 0.576 × C.

Q2: How does buffer capacity change with pH?
A: Buffer capacity is highest near the pKa of the buffer system and decreases as pH moves away from pKa in either direction.

Q3: What are typical buffer capacity values?
A: Biological buffers typically have β values between 0.01-0.1 mol/L pH. Blood has β ≈ 0.03 mol/L pH.

Q4: Can this calculator be used for polyprotic acids?
A: No, this equation is for monoprotic weak acids. Polyprotic acids require more complex calculations.

Q5: How does temperature affect buffer capacity?
A: Temperature affects Ka values, which in turn affects buffer capacity. Always use Ka values measured at the relevant temperature.