The pure water storage tank is used to store pure water. In order to ensure the quality of stored water, it is necessary to disinfect it regularly. There are many disinfection methods, one of which is the use of hydrogen peroxide. However, how to detect the residue of hydrogen peroxide after disinfection?

First, you need to prepare some tools and reagents. Tools include measuring cylinder, pipette, burette, etc. The reagents include potassium sulfate, potassium ferricyanide, sulfuric acid, phenolphthalein, etc.

Next, carry out detection according to the following steps:

1. Take a certain amount of pure water sample, put it into a measuring cylinder, and record the volume of the sample.

2. Adding a certain amount of potassium sulfate and potassium ferricyanide, the hydrogen peroxide in the sample reacts with potassium ferricyanide to form a blue complex.

3. Add sulfuric acid to stop the reaction.

4. Add phenolphthalein indicator to make the solution pink.

5. Titrate with standard sodium hydroxide solution until the solution turns deep red.

6. Record the volume of sodium hydroxide solution used for titration.

7. Calculate the concentration of hydrogen peroxide according to the reaction equation.

Through the above steps, the residual amount of hydrogen peroxide in the pure water storage tank can be detected. If the residual amount exceeds the standard value, it needs to be disinfected again until the residual amount of hydrogen peroxide meets the standard requirements.