1. What is the Buffer Equation?

The Buffer Equation (Henderson-Hasselbalch equation) calculates the pH of a buffer solution from the pKa of the acid and the concentrations of the conjugate base [A⁻] and weak acid [HA]. It's fundamental in chemistry and biochemistry for understanding buffer systems.

2. How Does the Calculator Work?

The calculator uses the buffer equation:

Where:

• \( pH \) — pH value (dimensionless)
• \( pKa \) — Acid dissociation constant (dimensionless)
• \( [A⁻] \) — Concentration of conjugate base (mol/L)
• \( [HA] \) — Concentration of weak acid (mol/L)

Explanation: The equation relates the pH of a solution to the pKa of the acid and the ratio of concentrations of the conjugate base to the weak acid.

3. Importance of pH Calculation

Details: Accurate pH calculation is crucial for understanding chemical equilibria, preparing buffer solutions in laboratories, and various applications in biological systems and industrial processes.

4. Using the Calculator

Tips: Enter pKa value, concentrations of [A⁻] and [HA] in mol/L. All concentration values must be positive numbers greater than zero.

5. Frequently Asked Questions (FAQ)

Q1: What is the valid range for pKa values?
A: pKa values typically range from -2 to 16 for most acids, though the equation works for any real number value of pKa.

Q2: What units should concentrations be in?
A: Both [A⁻] and [HA] should be in the same concentration units (typically mol/L) for the ratio to be valid.

Q3: When is the buffer equation most accurate?
A: The equation is most accurate when the concentrations of [A⁻] and [HA] are significantly larger than the concentration of H⁺ and OH⁻ ions.

Q4: Can this equation be used for strong acids?
A: No, the Henderson-Hasselbalch equation is specifically designed for weak acid buffer systems and is not applicable to strong acids.

Q5: What if the ratio [A⁻]/[HA] is negative?
A: Since concentrations cannot be negative, the ratio will always be positive. The calculator validates that inputs are greater than zero.