Peroxydisulfuric Acid: Overview, Questions, Preparation

In 1891, Prof. Marshall, a Scottish chemist, invented persulphates, which are popularly known as Marshall acid. 

Peroxydisulfuric acid is hygroscopic, colourless, and it is a strong peroxy acid. Peroxydisulfuric acid is an inorganic material that has the chemical formula H2S2O8. There are two methods to get peroxydisulfuric acid. We extract peroxydisulfuric acid with the help of a reaction of chlorosulfuric acid with hydrogen peroxide. The second process is the electrolysis of moderately concentrated sulfuric acid (65-75%) with platinum electrodes at high current density and voltage, where ozone is a by-product. Its solid form is hard to obtain, and we can get the final product as a solution of peroxydisulfuric acid. Its salts, usually referred to as persulfates, are industrially significant as powerful oxidising agents. Peroxydisulfuric acid is a robust oxoacid, and hence, the salts of peroxydisulfuric acid are frequently used in chemical reactions. Peroxydisulfuric acid contains sulphur in its +6 oxidation state and a peroxide group.

We can learn about the chemical properties of peroxydisulfuric acid through chemical reactions. 

Peroxydisulfuric acid dissolves in water and forms hydrogen peroxide and sulphuric acid. 

• H2S2O8 + 2H2O H2O2 + 2H2SO4

Peroxydisulfuric acid reacts with silver nitrate in a watery medium and forms silver oxide, sulphuric acid, and nitric acid.

• H2S2O8 + 2AgNO3 + 2H2O Ag2O2 + 2H2SO4 + 2HNO3

Pure peroxydisulfuric acid is not available for sale in the market, but the salts are more readily available. Peroxydisulfuric is highly destructive and can explode in touch with certain organic materials. Peroxydisulfuric acid is not very stable, but one source of scientists demands that it stays relatively stable at low temperatures, for up to 8 weeks. Watery solutions of peroxydisulfuric acid are more stable at 0-17 °C. For disposal, it should be dissolved in water and neutralised with a reducing agent. 

The Acids, Bases, and Salts chapter has a weightage of 3 marks in the 10th exam, and it focuses on acid, base, and salt and their properties.

1. What happens to the hydrolysis process of peroxydisulfuric acid?

Answer: The hydrolysis processing of peroxydisulfuric acid produces H2O2 and sulfuric acid.

H2S2O8 + 2H2O → 2H2SO4 + H2O2

2. Name the salts that are routinely used as oxidising agents.

Answer: Habitual salts include sodium, potassium, and ammonium salts that work as oxidising agents.

3. What is the process of electrolytic oxidation to produce peroxydisulfuric acid?

Answer: Electrolytic oxidation of bisulfate is a routine method of producing peroxydisulfuric acid.

2HSO4-→ H2S2O8+2e-

Q: What is the chemical formula of Peroxydisulfuric acid?

Q: What are the other names of peroxydisulfuric acid?

Q: What must be the oxidation number of sulphur in H2S2O8?

Q: What is oleum formula?

Q: What is the meaning of oleum?