Explore how buffers resist pH change using the Henderson-Hasselbalch equation
Buffer: A solution containing a weak acid (HA) and its conjugate base (A⁻) that resists pH change when small amounts of acid or base are added.
Buffer Composition
pH = pKa + log([A⁻]/[HA]) = 4.76
Buffer pH
4.76
[A⁻]/[HA] = 1.00
Test Buffer Resistance
Add small amounts of strong acid (HCl) or strong base (NaOH) and compare pH change.
Solution
Initial pH
After addition
ΔpH
Buffered
4.76
—
—
Unbuffered (water)
7.00
—
—
Buffered vs Unbuffered pH
Buffered solution
Unbuffered water
Biological Importance: Blood plasma is buffered at pH 7.4 by the carbonic acid/hydrogen carbonate buffer system (H₂CO₃/HCO₃⁻). Even small pH changes (>0.1) can cause acidosis or alkalosis, leading to serious health problems. The respiratory and renal systems work together to maintain this critical balance.