How to make sulfuric acid

Sulfuric acid is a highly corrosive chemical that is often used in laboratory chemical experiments. It is a type of oxygen-containing acid with strong oxidizing and acidic properties. Sulfuric acid is divided into concentrated sulfuric acid and dilute sulfuric acid, which are mainly divided by mass fraction and concentration. The preparation of sulfuric acid is mostly used for experimental research. When making it, you must take protective measures, wear gloves, lab coats, masks, etc. The specific preparation method is as follows:

Instruments such as dilute sulfuric acid, crucible, alcohol lamp, crucible tongs, etc. are required. Only concentrated sulfuric acid is produced by heating and evaporation.

2. Steps:

The composition of dilute sulfuric acid is sulfuric acid dissolved in water and then decomposed. Water can be evaporated by heating, thus achieving the effect of increasing the concentration of sulfuric acid. ① Preparation of sulfur dioxide: burning sulfur or high-temperature treatment of pyrite to produce sulfur dioxide (there is a lot of pyrite in China, so pyrite is often used); ② Sulfur dioxide is oxidized into sulfur trioxide when in contact with oxygen; ③ Use 98.3% sulfuric acid to absorb sulfur trioxide to obtain concentrated sulfuric acid.

① Laboratory preparation method: FeSO4·7H2O can be used to increase the heat, and then a U-shaped tube with ice-water mixture can be used to condense it. SO2 can be absorbed by NaOH, and theoretically 29.5% H2SO4 can be obtained. The key lies in exhaust gas absorption. Sulfur dioxide gas can be passed into hydrogen peroxide to produce sulfuric acid, but this method has a lower usage rate. Another lesser known method is to add 12.6M hydrochloric acid to the metabisulfite (S2O52-) and then add the resulting gas to nitric acid, which will release a brown/red gas. When no more gas is produced, the reaction is complete.

②Industrial production method: The raw materials for producing sulfuric acid include sulfur, pyrite, non-ferrous metal smelting flue gas, gypsum, hydrogen sulfide, sulfur dioxide and waste sulfuric acid. Sulfur, pyrite and smelting flue gas are the three main raw materials.

Sulfur dioxide is produced by burning sulfur or treating pyrite at high temperature, which is then oxidized to sulfur trioxide by contact oxidation (contact chamber) and absorbed by 98.3% sulfuric acid (absorption tower). Add water and purify. Industrial concentrated sulfuric acid can be distilled to obtain commercial sulfuric acid with a concentration of 95% to 98%. After the dihydrate phosphoric acid reaction, phosphogypsum is used for industrial recycling and sulfuric acid is produced using the dihydrate process.