Aim

The main aim of this lab is to help the students to understand the concept of pH and buffers and to optimally use pH meter to make the buffer solutions with accuracy which is the foundation for successful advanced experiments. To provide the method for the preparation of buffers with precision to deal with molecules and macromolecules that mostly are weak electrolytes of biochemical importance. The lab also will enable the application of the method for the determination of the pH of the soil, various juices, and other products where pH is an important criterion for their purity and optimal function.

After performing this experiment, students will be able to:

1. Understand the Concept of pH:

• Explain the meaning of pH as the negative logarithm of hydrogen ion concentration.
• Interpret the pH scale (0-14) and classify solutions as acidic, neutral, or basic.

2. Comprehend the Principle of Buffer Action:

• Describe how buffer solutions resist changes in pH upon the addition of small amounts of acid or base.
• Differentiate between acidic and basic buffers with suitable examples.

3. Apply the Henderson-Hasselbalch Equation:

• Use the equation to calculate the ratio of conjugate acid and base required to prepare a buffer of a given pH.
• Predict how the ratio of salt to acid affects the pH and buffer capacity.

4. Prepare Buffers Accurately:

• Prepare buffer solutions such as phosphate, carbonate-bicarbonate, and acetate buffers of specific pH and molarity.
• Utilize a pH meter effectively for pH measurement and adjustment using dilute acid or base.

5. Evaluate Buffer Capacity:

• Understand the concept of buffer capacity and identify the conditions for maximum buffering action (pH ≈ pKa).

6. Perform Example Calculations:

• Carry out quantitative calculations to determine the required amounts of acid and conjugate base for a desired pH.

7. Apply pH Determination in Real Samples:

• Extend the method to measure the pH of environmental and biological samples such as soil, fruit juices, and water, where pH is a critical parameter of purity and function.