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Henderson-Hasselbalch Equation:
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The Henderson-Hasselbalch equation is used to estimate the pH of a buffer solution from the pKa of the acid and the concentrations of the acid and its conjugate base. It provides a simple way to understand and predict buffer behavior in chemical and biological systems.
The calculator uses the Henderson-Hasselbalch equation:
Where:
Explanation: The equation shows that the pH of a buffer depends on the pKa of the acid and the ratio of base to acid concentrations. When [A⁻] = [HA], pH = pKa.
Details: Accurate pH calculation is crucial for preparing buffer solutions in biochemical experiments, pharmaceutical formulations, and many industrial processes where maintaining a stable pH is essential.
Tips: Enter pKa value, base concentration in M, and acid concentration in M. All concentrations must be positive values. The calculator will compute the pH using the Henderson-Hasselbalch equation.
Q1: What is the valid range for the Henderson-Hasselbalch equation?
A: The equation works best when the concentration ratio [A⁻]/[HA] is between 0.1 and 10, which corresponds to pH values within ±1 unit of the pKa.
Q2: Why is the Henderson-Hasselbalch equation important in biochemistry?
A: It's essential for designing buffer systems that maintain stable pH in biological experiments, as many biological processes are highly pH-sensitive.
Q3: What are the limitations of this equation?
A: The equation assumes ideal behavior and may be less accurate at very high or very low concentrations, or when ionic strength effects are significant.
Q4: Can this equation be used for polyprotic acids?
A: For polyprotic acids, the equation can be applied to each dissociation step separately, considering the appropriate pKa and concentrations for each pair.
Q5: How does temperature affect the calculation?
A: Temperature affects both pKa values and the autoprotolysis of water, so pKa values should be appropriate for the temperature at which the buffer will be used.