Activity Project: Determination of pH of Various Solutions

Objective

To measure and compare the pH of different everyday solutions using pH paper or a pH meter.

Materials Required

• pH meter or pH indicator paper/strips
• Solutions to test: Lemon juice, lime water, soap solution, distilled water, vinegar, baking soda solution
• Test tubes or small containers
• Dropper or pipette
• Clean glass stirring rods

Procedure

1. Label small containers with the names of the solutions to be tested.
2. Pour a small quantity (about 10 mL) of each solution into respective containers.
3. If using pH paper, dip one strip into each solution for 1-2 seconds and observe color change immediately; compare with pH color chart.
4. If using a pH meter, calibrate it first, then immerse the electrode into each solution and record the reading once stable.
5. Record all observations in a table format.
6. Clean the electrode between measurements if using a pH meter.

Observation Table

Solution	Type	Expected pH Range	Observed pH	Acidic / Neutral / Basic
Lemon Juice	Natural acid	2.0 – 3.0	2.5	Acidic
Lime Water	Alkaline solution (Ca(OH)₂)	11.0 – 12.5	11.8	Basic
Soap Solution	Soapy alkaline	9.0 – 10.5	9.5	Basic
Distilled Water	Pure water	6.5 – 7.5	7.0	Neutral
Vinegar	Acetic acid solution	2.5 – 3.0	2.7	Acidic
Baking Soda Solution	Basic (sodium bicarbonate)	8.0 – 9.0	8.4	Basic

Result

The pH values of the solutions varied as expected, demonstrating the acidic, basic, or neutral nature of the substances tested.

Precautions

• Do not contaminate solutions; use clean containers and equipment.
• Calibrate pH meter properly before use.
• Use pH paper within expiry date for accurate results.
• Record pH readings promptly before they change.