Laboratory Experiments of B.Sc. II Sem BT/FS/CBZ - Experiment: 5

  Laboratory Experiments of B.Sc. II Sem BT/FS/CBZ

 

Dr. Navdeep Sharma
Institute of Sciences
SAGE University, Indore (M.P.)

 

Experiment: 5

Objective:

To determine the pH values of various household and food items using pH paper or a pH meter and classify them as acidic, basic, or neutral.

Materials Required:

·         pH paper (universal indicator strips) or digital pH meter

·         Clean test tubes or beakers

·         Distilled water

·         Dropper or stirring stick

·         Glass rod

·         Filter paper (if needed)

Samples for Testing:

1. Shampoo
2. Soap solution
3. Lemon juice
4. Orange juice
5. Tomato juice
6. Vinegar
7. Milk
8. Curd
9. Baking soda solution
10. Toothpaste slurry
11. Soft drink (cola)
12. Apple or banana pulp extract
13. Tap water
14. Detergent solution
15. Salt solution (NaCl in water)

Theory:

The pH scale (ranging from 0 to 14) indicates the acidity or basicity of a substance:
 pH < 7 → Acidic
 pH = 7 → Neutral
 pH > 7 → Basic

       Everyday substances contain acids (like citric or lactic acid) or bases (like ammonia, sodium hydroxide), and checking their pH helps understand their chemical nature.

Procedure:

1. Preparation of Samples:

·         If a substance is solid or thick (like fruit pulp, toothpaste, soap), make a dilute solution or extract using distilled water.

·         For liquids, use them directly or filter if necessary.

2. Using pH Paper:

·         Dip a strip of universal pH paper into each sample or place a drop of the sample on the

·         paper Wait for a few seconds until the color develops.

·          Compare the color with the pH scale chart provided with the paper.

3. Using pH Meter

·         Calibrate the pH meter using standard buffer solutions (pH 4, 7, and 10).

·         Rinse the electrode with distilled water.

·         Dip the electrode into each sample and record the pH value once it stabilizes.

·         Rinse the electrode between tests.

4. Record Your Observations:

·         Note the color of the pH strip or digital pH reading.

·         Classify each substance as acidic, basic, or neutral.

Observation Table:

S. No.	Substance	Observed pH	Nature (Acidic/Basic/Neutral)
1	Shampoo
2	Soap solution
3	Lemon juice
4	Orange juice
5	Tomato juice
6	Vinegar
7	Milk
8	Curd
9	Baking soda solution
10	Toothpaste slurry
11	Soft drink (cola)
12	Apple pulp
13	Banana pulp
14	Tap water
15	Salt solution

Result:

The pH values of common substances were determined successfully. Substances were classified as acidic, basic, or neutral based on their pH readings.

Precautions:

·         Use clean droppers and test tubes for each sample.

·         Do not mix samples or reuse the same strip.

·         Rinse the pH meter probe with distilled water between each reading.

·         Dispose of used materials properly.