Created By : Rina Nayak

Reviewed By : Phani Ponnapalli

Last Updated : Apr 25, 2023

Buffer pH calculator is a tool to know the pH of the buffer solution. To get buffer pH as output, all you need to do is give inputs i.e the buffer type, dissociation constant of an acid, acid concentration in (M/mM/µM) and salt concentration in(M/mM/µM), and then click on the calculate button to get the accurate value of pH of the buffer solution.

Buffer type
Ka
Acid concentration
Salt concentration
pH

### Buffer - Definition

A buffer is a solution that contains weak acid and its salt or weak base and its salt. Buffers are used to maintain the original pH when combined with acid or base. pH buffers are often known as a hydrogen ion buffer and are aqueous solutions which have a traceable pH value that alters negligibly when combined with small amounts of acids or bases. pH buffers are usually made up of a combination of a conjugate base and a weak acid that absorbs excess hydrogen atoms to retain a stable pH value in solution.

### pH of a Buffer Solution Formula

The pH of the buffer can be calculated by the formula pH = pKa + log10 ([A-]/[HA]). This equation is called the Henderson - Hasselbalch Equation.

• Where, [A-] is the concentration of a base in a buffer.
• [HA] is the concentration of an acid in a buffer.
• pKa is the dissociation constant of an acid

By using this Henderson - Hasselbalch equation We can get the value of pH of the buffer solution. Another way to find the pH of the buffer solution is as follows

Molar solution equation: desired molarity × formula weight × solution final volume (L) = grams needed

Percentage by weight (w/v): (% buffer desired / 100) × final buffer volume (mL) = g of starting material needed.

### How do you calculate pH of a Buffer?

Simple and easy steps to find the pH of the buffer by using the buffer pH calculator is listed below

• Step 1: Enter the type of buffer either acid or base buffer.
• Step 2: Know the values of dissociation constant of an acid or base concentration or salt concentration.
• Step 3: Find the value of log of ratio of the concentration of conjugate base to the acid concentration.
• Step 4: Enter the values and click the calculate button to find the pH of the buffer solution.

### Buffer Solution pH Solved Problems

Question 1: Calculate the pH of the buffer solution made from 0.20M HC2H3O2 and 0.50 M C2H3O2- that has an acid dissociation constant for HC2H3O2 of 1.8 x 10-5?

Solution:

Given that,

Ka = 1.8 x 10-5

pKa is the dissociation constant of an acid = -log(1.8 x 10-5 )

= 4.7

[A-] is the concentration of a base in a buffer = 0.50M

[HA] is the concentration of an acid in a buffer = 0.20M

The formula for buffer pH is pH = pKa + log10 ([A-]/[HA]). This equation is called theHenderson - Hasselbalch equation

Substitute the values in the equation,

pH = pKa + log10 ([A-]/[HA])

= 4.7 + log(0.50 / 0.20)

= 4.7 + 0.40 = 5.1

Therefore pH of the buffer solution is = 5.1

### FAQ’s on Buffer pH Calculator

1. What is the formula for Buffer pH?

The formula for buffer pH is pH = pKa + log10 ([A-]/[HA]). This equation is called theHenderson - Hasselbalch equation.

• [A-] is the concentration of a base in a buffer.
• [HA] is the concentration of an acid in a buffer.
• pKa is the dissociation constant of an acid

2. What is the range of a buffer solution?

The buffer range is the pH range where a buffer effectively neutralizes added acids and bases, while maintaining relatively constant pH.

3. In what range of pH is a buffer most effective?

Buffers are generally good over the range pH=pKa± 1.

4. What are the factors that affect the pH of a buffer?

The buffer pH can be affected by two factors: the equilibrium constant Ka of the weak acid and the ratio of weak base to the weak acid in the chemical solution.

5. What is the difference between pH and buffer pH?

pH is a fundamental scale that we use in chemistry to measure the acidity or basicity of a solution. Buffers are chemical solutions that can resist the changes in pH. The difference between pH and buffer pH is that the pH is a logarithmic scale whereas buffer is an aqueous solution.