Titration of Strong Acid HCl with Strong Base NaOH

Hydrochloric Acid (HCl) Titration

Theory

Titration of a strong acid and a strong base involves a neutralization reaction:

$$\text{NaOH} + \text{HCl} \rightarrow \text{NaCl} + \text{H}_2\text{O}$$

During titration, the pH of the solution taken in the conical flask changes as the other solution is added from the burette. If NaOH is added from the burette and HCl is taken in the conical flask, during the titration the pH of the solution in the conical flask will increase.

Procedure

1. Take a clean burette, rinse it with 0.1 M NaOH solution, and then fill it with this solution.
2. Rinse the pipette with 0.1 M HCl solution. Pipette out 10.0 mL of 0.1 M HCl into the conical flask and add about 2–3 drops of the universal indicator solution to it.
3. Note down the colour of the solution in the conical flask.
4. Now, add 0.1 M NaOH from the burette to the solution slowly. Record the volume of NaOH used for every change in colour.
5. Record the colours in the solution in the conical flask in the observation table.
6. At the end point, when the amount of HCl has been completely neutralized by NaOH, the extra drop of strong alkali will impart a distinct purple colouration due to the high pH range of 12–14.

Protocol Summary: Hydrochloric Acid (HCl)

Theory

Titration of a strong acid and a strong base involves a neutralization reaction:

$$\text{NaOH} + \text{HCl} \rightarrow \text{NaCl} + \text{H}_2\text{O}$$

During titration, the pH of the solution taken in the conical flask changes as the titrant is added from the burette. If NaOH is added from the burette and HCl is taken in the conical flask, during the titration the pH of the solution in the conical flask will increase.

Procedure

1. Take a clean burette and rinse it with 0.1 M NaOH solution, then fill it with this solution.
2. Rinse the pipette with 0.1 M HCl solution. Pipette out 10.0 mL of 0.1 M HCl into the conical flask and add about 2–3 drops of the universal indicator solution to it.
3. Note down the colour of the solution in the conical flask.
4. Now add 0.1 M NaOH from the burette to the solution slowly. Record the volume of NaOH used for every change in colour.
5. Record the colours of the solution in the conical flask in the observation table.
6. At the end point, when the amount of HCl has been completely neutralized by NaOH, the extra drop of strong alkali will impart a purple colouration due to the high pH range of 12–14.