Calculate The Ph Of A Buffer Solution That Is 0.200 M In And 0.100 M In

Henderson-Hasselbalch Equation:

\[ pH = pKa + \log\left(\frac{[A^-]}{[HA]}\right) \]

Acid Dissociation Constant (pKa):

(dimensionless)

Conjugate Base Concentration [A⁻]:

mol/L

Weak Acid Concentration [HA]:

mol/L

Buffer Solution pH:

Unit Converter ▲

Unit Converter ▼

From:	To:

1. What is the Henderson-Hasselbalch Equation?

The Henderson-Hasselbalch equation is used to estimate the pH of a buffer solution from the pKa of the weak acid and the concentrations of the weak acid and its conjugate base. It provides a convenient way to calculate and prepare buffer solutions with specific pH values.

2. How Does the Calculator Work?

The calculator uses the Henderson-Hasselbalch equation:

\[ pH = pKa + \log\left(\frac{[A^-]}{[HA]}\right) \]

Where:

\( pH \) — The calculated pH of the buffer solution (dimensionless)
\( pKa \) — Acid dissociation constant of the weak acid (dimensionless)
\( [A^-] \) — Concentration of conjugate base (mol/L)
\( [HA] \) — Concentration of weak acid (mol/L)

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

3. Importance of Buffer pH Calculation

Details: Accurate pH calculation is crucial for preparing buffer solutions in biochemical experiments, pharmaceutical formulations, and various analytical procedures where maintaining a stable pH is essential.

4. Using the Calculator

Tips: Enter the pKa value of the weak acid, the concentration of the conjugate base, and the concentration of the weak acid. All concentrations must be positive values.

5. Frequently Asked Questions (FAQ)

Q1: What is the valid range for the Henderson-Hasselbalch equation?
A: The equation works best when the ratio [A⁻]/[HA] is between 0.1 and 10, which corresponds to pH values within ±1 unit of the pKa.

Q2: Why are buffer solutions important?
A: Buffer solutions resist changes in pH when small amounts of acid or base are added, making them essential in biological systems and chemical processes.

Q3: What are common buffer systems?
A: Common buffer systems include acetate (pKa = 4.76), phosphate (pKa = 7.21), and Tris (pKa = 8.08) buffers.

Q4: Are there limitations to this equation?
A: The equation assumes ideal behavior and may not be accurate for very concentrated solutions or when ionic strength effects are significant.

Q5: Can this calculator be used for basic buffers?
A: For basic buffers (weak base + its conjugate acid), a modified form of the equation is used: pH = 14 - pKb - log([BH⁺]/[B]).