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Titration of a Strong Base Using Universal Indicator Experiment

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What is a Titration Experiment?

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While performing any experiment, it is important to know the amount of substance present. This titration is the same process that lets you identify the amount of substance present and to know its proportion.

When we mix any other substance to an unknown amount of one substance, it is known as titration. You can quickly identify the unknown amount of one substance with the reaction taking place. The results gained are in the form of proportion in which the two substances mix. An experimental observation is made when titrant or titrating reagent is added in the definite amount using a burette having a stop cock.


Titration Experiment

Suppose you are given a substance or solution with an unknown amount, and your goal is to find the amount of substance available to you, the process of titration is used in such cases. In the experiment, you will be using the known amount of substance or solution and add to that unknown amount. When this universal indicator or titrating reagent brings a change in the solution’s colour, the point of equivalence is reached.

Initially, you will observe a slow change in the shade of the solution. However, be careful when you are about to reach the point of equivalence. The changes observed at that time are very rapid.


Example of Titration

Titration can be done with:

  • Strong Acid with universal Indicator.

  • Strong Acid with Strong Base.

  • Strong Base with Universal Indicator.

Below we will study the titration of a Strong Base using the Universal Indicator experiment.

Performing The Experiment

Aim of the Experiment:

To study the change in pH value with titration of a strong base using universal indicator experiment.


Things Required:

One burette, 2beakers of 250 ml each, a conical flask of 100 ml, 25 ml of  Hydrochloric acid with 0.1 M, a dropper, a pH chart, 50 ml of sodium hydroxide solution of 0.1 M, and a universal indicator.


Setting Up Experiment Base:


In the above picture, a burette is set on a stand having a stop cock. A flash is kept at the base having a base or acidic indicator. Burette will be containing a base or acid to which you want to test.


Procedure to Follow:

  • In the conical flask kept at the base, take Hydrochloric acid with 0.1 M.

  • As you have taken acid in the flask, add a base to the burette. Add Sodium hydroxide with 0.1 M.

  • Now add two-three drops of universal indicator in the conical flask kept at the base.

  • Open the stop cock, and keep adding a base to acid drop by drop. Also, keep shaking the flask simultaneously.

  • Keep observing the flask and note down if colour change content is observed. Every time you keep adding solution from the burette, keep noting the colour and compare it with the pH value scale.

  • Note down your observation in the observation table.

  • Also, plot a final graph for pH V/s for the total volume of NaOH used from the burette.

Observations:

As you keep adding NaOH to HCl, you need to keep observing when it finally reaches its neutral point, with each observation made drop by drop.

The below table is used to note down your NaOH observations used in 25 ml of HCl with both 0.1 M.


Sl. No.

NaOH Amount Taken

NaOH Amount Added to the Flask

pH

1

0

0


2

12.5

12.5


3

10

22.5


4

2.3

24.8


5

0.1

24.9


6

0.1

25


7

0.1

25.1


8

0.1

25.1


9

0.1

25.3


10

0.1

25.4


11

0.5

25.9



Precautions to Take While Performing Titration Experiment:

  • The concentration of both strong acid and strong base must be the same.

  • Use the minimum indicator as possible.

  • Do not open the stop cock at once. Be sure to add a base to acid drop by drop.

What are The Different Viva Voice Questions for Reference?

  • How will you define titrate in your terms?

  • What is titrant according to you?

  • What should be the final pH value for the experiment performed?

  • What will happen if you perform the same experiment with a strong base and a weak acid?

FAQ (Frequently Asked Questions)

1. Which Universal Indicator will You Use to Perform Titration in Strong Acid and Weak Base?

Ans: The basic preferred indicator to perform a titration experiment between a strong acid and a strong base is the phenolphthalein indicator. The reason behind choosing this indicator is its pH value range that lies from 8.3 to 10. The phenolphthalein indicator changes its colour to clear, and in basic solutions in acidic solution, and it changes its colour to pink. However, before experimenting using this universal indicator, ensure that both strong acid and strong base should have the same concentration. During the experiment, make sure to take only a few drops of indicator and add a base to acid drop by drop. It is because neutralisations take place within a few drops.

2. How do You Know Which Indicator Should You Use for Titration?

Ans: Before you start experimenting using any universal indicator, make sure to check its pH value range. The fact is the pH value range of an indicator must fall within the range of reaction taking place. Suppose let us take an example for this. If you are experimenting with a strong acid and a strong base, the pH will frequently change from 3 to 11 by adding a few drops into it. The indicator will not be able to depict the pH range outside the reaction taking place. Thus be sure to take an indicator having a range of 6-10 in such a case. Another example is methyl red, whose pH range is 4 to 6. Thus it cannot depict from 1 to 4 and 6 or above.