Henderson-Hasselbalch Calculator
Calculate buffer pH using the Henderson-Hasselbalch equation: pH = pKa + log([A⁻]/[HA]).
How to Use the Henderson-Hasselbalch Calculator
- Enter the pKa of the weak acid.
- Enter the concentration of the conjugate base [A⁻].
- Enter the concentration of the weak acid [HA].
- Click Calculate to get the buffer pH and base/acid ratio.
حالات الاستخدام
- •Designing buffers for biochemistry and cell biology experiments.
- •Calculating the pH of blood bicarbonate buffer system.
- •Teaching acid-base chemistry and buffer capacity concepts.
الصيغة
Henderson-Hasselbalch: pH = pKa + log([A⁻]/[HA]). [A⁻] = conjugate base concentration, [HA] = weak acid concentration.
الأسئلة الشائعة
When is the Henderson-Hasselbalch equation valid?
The equation is most accurate when the ratio [A⁻]/[HA] is between 0.1 and 10 (i.e., pH within 1 unit of pKa), and for weak acids and bases with Ka values between 10⁻³ and 10⁻¹¹.
How do I choose a buffer for a target pH?
Select a weak acid whose pKa is within 1 unit of your target pH. Then adjust the [A⁻]/[HA] ratio to fine-tune the pH. For example, PBS uses sodium phosphate with pKa ≈ 7.2.
Disclaimer
For educational and laboratory purposes only. Actual buffer pH may differ due to ionic strength, temperature, and activity coefficients. Always verify with a calibrated pH meter.