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Chemical Sciences
Biochemistry
1909
Intermediate

Henderson-Hasselbalch Equation

pH=pKa+log⁡[A−][HA]\text{pH} = \text{p}K_a + \log\frac{[A^-]}{[HA]}

pH of a buffer solution relates to acid dissociation constant and conjugate base ratio.

By Lawrence Henderson, Karl Hasselbalch

Chemical Sciences
Henderson-Hasselbalch Equation
1909 · Lawrence Henderson
Why it matters: Essential for understanding blood pH, biological buffers, and lab chemistry.

Discoverers: Lawrence Henderson, Karl Hasselbalch (1909)

What does it mean?

pH of a buffer solution relates to acid dissociation constant and conjugate base ratio.

Why should I care?

Essential for understanding blood pH, biological buffers, and lab chemistry.

Variables & Units

SymbolNameUnitMeaning
pHpHpH—Acidity measure
pKapKapKa—Acid dissociation constant
[A−][A⁻]Conjugate base—Deprotonated form
[HA][HA]Acid—Protonated form

Worked Example

Equal [A⁻] and [HA] → pH = pKa.

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Sources & further reading

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Equation Universe

Henderson-Hasselbalch Equation

pH=pKa+log⁡[A−][HA]\text{pH} = \text{p}K_a + \log\frac{[A^-]}{[HA]}

Real-world impact

Blood pH regulation

Essential for understanding blood pH, biological buffers, and lab chemistry.

Photo: Unsplash — technology

pH of a buffer solution relates to acid dissociation constant and conjugate base ratio.

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