Buffer Capacity Calculator
Calculate the buffer capacity (β) of a buffer solution. Buffer capacity measures how well a buffer resists changes in pH when strong acid or base is added.
Amount of strong acid (H⁺) or base (OH⁻) added in moles
Absolute change in pH after adding the acid or base
Volume of the buffer solution in liters (optional, for concentration-based capacity)
What is buffer capacity?
Buffer capacity (β) measures a buffer solution's resistance to pH change when strong acid or base is added. It is defined as the amount of strong acid or base (in moles) needed to change the pH by one unit, per liter of buffer: β = Δn / (V × ΔpH). Higher values indicate greater buffering ability.
How do you calculate buffer capacity?
Buffer capacity is calculated using the formula β = Δn / (V × ΔpH), where Δn is moles of strong acid or base added, V is buffer volume in liters, and ΔpH is the change in pH. If volume is not provided, β = Δn / ΔpH gives the buffer capacity in moles per pH unit.
What factors affect buffer capacity?
Buffer capacity depends on the total concentration of the buffer components (weak acid and its conjugate base, or weak base and its conjugate acid). Maximum buffer capacity occurs when pH = pKa of the weak acid, meaning [A⁻] = [HA]. Higher concentrations provide greater buffer capacity.
Why do buffers have limited capacity?
Buffers work by neutralizing added H⁺ or OH⁻ through equilibrium reactions. Once one component is exhausted (e.g., all conjugate base is converted to weak acid), the buffer can no longer resist pH changes effectively. This is why buffer capacity has a finite limit.