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Henderson-Hasselbalch Equation For Phosphate Buffer:
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The phosphate buffer system is an important biological buffer that helps maintain pH stability in cells and bodily fluids. It consists of dihydrogen phosphate (H₂PO₄⁻) and monohydrogen phosphate (HPO₄²⁻) ions.
The calculator uses the Henderson-Hasselbalch equation:
Where:
Explanation: The equation relates the pH of a buffer solution to the pKa of the acid and the ratio of concentrations of the conjugate base and acid.
Details: Accurate pH calculation is crucial for preparing buffer solutions in biological research, pharmaceutical applications, and clinical laboratories to maintain stable pH conditions.
Tips: Enter pKa value (typically 7.2 for phosphate buffer at 25°C), concentrations of phosphate and hydrogen phosphate ions in mol/L. All values must be positive numbers.
Q1: What is the typical pKa value for phosphate buffer?
A: The pKa for the H₂PO₄⁻/HPO₄²⁻ system is approximately 7.2 at 25°C, but it can vary slightly with temperature and ionic strength.
Q2: What is the effective buffering range of phosphate buffer?
A: Phosphate buffer is most effective in the pH range of 6.2-8.2, which covers the pKa ± 1 unit.
Q3: Why is phosphate buffer important in biological systems?
A: It's one of the major buffer systems in blood and intracellular fluids, helping maintain pH homeostasis in living organisms.
Q4: Are there limitations to using phosphate buffer?
A: Phosphate can precipitate with calcium ions and may interfere with some enzymatic reactions. It also has limited buffering capacity outside its pKa range.
Q5: How does temperature affect phosphate buffer pH?
A: The pKa of phosphate buffer decreases slightly with increasing temperature, approximately -0.0028 units per °C.