Henderson's Equation:
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Definition: Henderson's equation relates the pH of an acidic buffer solution to the concentrations of the weak acid and its conjugate base (salt).
Purpose: It helps chemists and biochemists calculate the required salt concentration to achieve a specific pH in a buffer solution.
The calculator uses Henderson's equation:
Where:
Explanation: The equation shows how the ratio of salt to acid concentrations determines the pH of a buffer solution.
Details: Accurate buffer preparation is crucial in biological systems, chemical experiments, and industrial processes where maintaining stable pH is essential.
Tips: Enter the acid concentration (mol/m³), desired pH, and the pKa of the acid. All values must be ≥ 0.
Q1: What is a buffer solution?
A: A solution that resists pH change when small amounts of acid or base are added, typically containing a weak acid and its conjugate base.
Q2: How do I find the pKa of an acid?
A: pKa values are tabulated in chemistry references or can be calculated from the acid's ionization constant (Ka).
Q3: What units should I use for concentration?
A: The calculator uses mol/m³, but you can convert from mol/L (M) by multiplying by 1000 (1 M = 1000 mol/m³).
Q4: Does this work for all pH values?
A: Henderson's equation is most accurate when pH is within ±1 unit of the pKa (effective buffer range).
Q5: Can I use this for basic buffers?
A: No, this calculator is specifically for acidic buffers. Basic buffers require a different form of Henderson's equation.