4. Study the pH change in the titration of 0.1 M HCl with 0.1 M NaOH using universal indicator.

Aim:- Study the pH change in the titration of 0.1 M HCl with 0.1 M NaOH using universal indicator.

Requirements:- Burette, pipette(20.0 ml), titration flask, beakers, funnel, universal indicator solution, 0.1 M HCl and 0.1 M NaOH.

Procedure:-

1. Take a clean burette and rinse it with 0.1 M HCl solution and then fill it with this solution.
2. Rinse the pipette with 0.1 M NaOH solution. Pipette out 20.0 ml of 0.1 M NaOH in the conical flask and add about 10 drops of the universal indicator solution to it.
3. Sueirl the solution until the colour of the solution becomes uniform. Compare the colour of the solution with the pH indicators chart and estimate the pH of the solution.
4. Now add 0.1 M HCl from the burette to the solution slowly. After addition of 1ml solution with pH indicator chart and estimate the pH of the Solution.
5. Keep on adding 0.1 M HCl and estimate the pH of the solution after addition of each 1 ml solution. In this way add about 30 ml of HCl solution and record the data in the table.

Observation:- Volume of 0.1 M NaOH solution taken = 20.0 ml.

Volume of 0.1 M HCl solution added (ml).	Colour of the solution.	Estimated pH.
1 ml	Dark violet	14
3 ml	violet	13
5 ml	Dark blue	12
7 ml	Blue	11
8 ml	Light Blue	10
9 ml	Green	6
10 ml	Yellow	4
10.5 ml	Orange	2
11 ml	Dark orange	1
14 ml	Red	0
15 to 30 ml	Red	0

Conclusion:- The pH of the solution decreases with addition of 0.1 M HCl. The decrease in pH show in Beginning. After addition of about 19.0 ml solution, the further addition shows a sharp fall in pH. After the sharp fall the decrease in pH again becomes slow. The point where there is a sharp fall in pH (from about 10 to 13) corresponding to the equivalent point.