Buffer pH Calculator
Calculate the pH of a buffer solution from acid concentration, base concentration, and pKa.
This tool is for informational and educational purposes only. It is not a substitute for professional financial, medical, legal, or engineering advice. See Terms of Service.
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Enter the pKa of your weak acid, the concentration of the weak acid, and the concentration of the conjugate base. The calculator computes pH using the Henderson-Hasselbalch equation and also reports the buffer capacity.
About the Buffer pH Calculator
Buffer solutions resist changes in pH when small amounts of acid or base are added. They consist of a weak acid and its conjugate base (or a weak base and its conjugate acid). Buffers are essential in biological systems, analytical chemistry, and industrial processes where pH stability is critical.
Frequently Asked Questions
What makes a good buffer?
A good buffer has a pKa close to the desired pH, and roughly equal concentrations of the weak acid and its conjugate base. The effective buffering range is typically pKa plus or minus 1 pH unit.
What is buffer capacity?
Buffer capacity measures how much acid or base a buffer can absorb before the pH changes significantly. It depends on the total concentration of the acid-base pair and peaks when [A-] = [HA] (i.e., pH = pKa).
How is this different from the Henderson-Hasselbalch calculator?
They use the same core equation. This calculator adds buffer capacity information and is framed for practical buffer preparation. The Henderson-Hasselbalch calculator focuses on the equation itself.