Step by Step Process to Calculate Buffer pH
Go through the simple and easy guidelines on how to find the buffer pH value.
- Know the acid dissociation constant, acid or base concentration and salt concentration
- Find the log of the ratio of the concentration of conjugate base to the acid concentration
- Add the result to the pKa to obtain the pH buffer value.
What is a buffer?
A buffer is a solution that contains either a weak acid and its salt or a weak base and its sale. Buffers are used to maintain the original pH when combined with an acid or base. The best example of a buffer is our blood.
The list of popular buffers and their pK are given here. The list is arranged from most acidic to most alkaline
|Aspartic acid||2.1, 3.9, 9.8|
|Phosphate||2.1, 7.2, 12.3|
|Citrate||3.1, 4.8, 6.4|
pH of a Buffer Solution
The pH of a buffer is based on the Henderson-Hasselbalch equation: pH = pKa + log([A⁻]/[HA])
Basic buffer pH formula is pH = 14 - pKb - log([B+]/[BOH])
pH = -log₁₀(H)
Ka is the acid dissociation constant
[HA] is the acid concentration
[A⁻] is the concentration of conjugate base
pKa = -log₁₀(Ka)
Question: A buffer solution was made by dissolving 10.0 grams of sodium acetate in 200.0 mL of 1.00 M acetic acid. Assuming the change in volume when the sodium acetate is not significant, estimate the pH of the acetic acid/sodium acetate buffer solution. The Ka for acetic acid is 1.7 x 10-5.
CH3COOH + H2O → H3O+ + CH3COO-
[H3O+] = Ka[CH3COOH]
[H3O+] = (1.7 x 10-5)(0.200/0.122)
= 2.79 x 10-5
pH = 4.56
Explore more Bio Chemistry Calculators from our site Chemistrycalc.Com and calculate all your chemistry problems easily at a faster pace.
FAQ’s on pH Buffer Calculator
1. What is the difference between pH and buffer pH?
pH is a fundamental scale that is used to measure the acidity or basicity of a solution. Buffers are chemical solutions that can resist changes in pH. We can use pH scale to determine the quality of water, soil and others. Buffers are used to maintain the correct pH for enzymatic activity.
2. How to calculate pH of a buffer?
The Henderson-Hasselbalch formula to find the pH is pH = pKa + log([A⁻]/[HA]). Substitute the values in the formula and solve to get the buffer pH value.
3. What is the most effective buffer pH range?
The most effective buffer range would be between 10:1 and 1:10.
4. What are the factors that affect the pH of the buffer?
The buffer pH can be affected by two factors they are equilibrium constant Ka of the weak acid and the ratio of weak base to the weak acid in the chemical solution.