The strength of H2O2 can be determined by titrating it with a known concentration of sodium thiosulfate (Na2S2O3) solution. In this case, KI is added to H2O2 in an acidic medium, resulting in the liberation of I2. The liberated I2 is then titrated with a 0.1N solution of sodium thiosulfate (hypo). The volume of hypo required to react completely with the liberated I2 can be used to calculate the strength of H2O2.

Here are the steps involved in the titration process:

1. Preparation of reagents:
- Prepare a 0.1N solution of sodium thiosulfate (hypo) by dissolving a known amount of Na2S2O3 in distilled water.
- Prepare a solution of KI by dissolving a known amount of KI in distilled water.

2. Titration procedure:
- Take 50ml of the prepared H2O2 solution and add it to a conical flask.
- Add a few drops of sulfuric acid (H2SO4) to make the medium acidic.
- Add a few drops of starch indicator to the flask. The starch will form a blue complex with the liberated I2.
- Slowly add the KI solution to the flask. The KI reacts with H2O2 to liberate I2, which reacts with the Na2S2O3 in the next step.
- The appearance of a blue color indicates the presence of free I2 in the solution.

3. Titration with hypo:
- Start adding the 0.1N sodium thiosulfate (hypo) solution slowly to the flask while swirling it continuously.
- The blue color of the solution will fade gradually as the hypo reacts with the I2.
- When the blue color disappears completely, stop adding hypo and note the volume of hypo used.

4. Calculation:
- The number of moles of I2 liberated can be calculated using the balanced chemical equation.
- The number of moles of Na2S2O3 used can be calculated by multiplying the volume used (in L) with the molarity of the hypo solution.
- Since the reaction between I2 and Na2S2O3 is 1:2, the number of moles of I2 can be determined by dividing the moles of Na2S2O3 by 2.
- The number of moles of H2O2 can be calculated by multiplying the moles of I2 with the molar ratio between H2O2 and I2.
- Finally, the strength of H2O2 can be calculated by dividing the mass of H2O2 (in g) by the volume of H2O2 used (in L).

By following these steps and performing the necessary calculations, the strength of H2O2 can be determined accurately.

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