Concentrated sulfuric acid storage

Concentrated sulfuric acid is an acidic chemical reagent. Because it is highly corrosive, human skin will be corroded when it comes into contact with it, causing burning pain. If concentrated sulfuric acid accidentally splashes on clothes, it will also burn a hole. Therefore, concentrated sulfuric acid must be stored with caution. Generally, concentrated sulfuric acid is placed in brown glass bottles, sealed and placed out of the reach of children. The following is a detailed introduction to the storage method of concentrated sulfuric acid.

Concentrated sulfuric acid, commonly known as bad water, has a chemical formula of H2SO4 and is a strong mineral acid with high corrosiveness. Concentrated sulfuric acid refers to a sulfuric acid solution with a mass fraction greater than or equal to 70%. Concentrated sulfuric acid is a strong oxidizing agent at high concentrations, which is one of the biggest differences between it and dilute sulfuric acid. At the same time, it is also dehydrating, highly corrosive, non-volatile, acidic, and water-absorbent.

Since concentrated sulfuric acid contains a large number of unionized sulfuric acid molecules (the acid molecules in a strong acid solution are not necessarily all ionized into ions, the strength of the acid is relative), concentrated sulfuric acid has special properties such as water absorption, dehydration (commonly known as carbonization, i.e. corrosiveness) and strong oxidizing properties; while in dilute sulfuric acid, the sulfuric acid molecules are completely ionized, so it does not have the special chemical properties of concentrated sulfuric acid. Oleum is a colorless or brown oily thick fuming liquid (brown because it contains a small amount of iron ions) with a strong pungent odor, strong water absorption, can be mixed with water in any proportion, and releases a large amount of dilution heat. Therefore, when diluting concentrated sulfuric acid, the concentrated sulfuric acid should be slowly injected into the water along the wall of the container and continuously stirred with a glass rod.

Physical properties

In addition to the inherent chemical properties of acids, concentrated sulfuric acid also has its own special properties, which are very different from dilute sulfuric acid. The main reason is that there are a large number of unionized sulfuric acid molecules in the concentrated sulfuric acid solution (sulfuric acid molecules can also undergo self-ionization). These sulfuric acid molecules give concentrated sulfuric acid very strong properties.

Pure sulfuric acid is a colorless, odorless, oily liquid. The mass fraction of H2SO4 in commonly used concentrated sulfuric acid is 98.3%, its density is 1.84g·cm-3, and its molar concentration is 18.4mol·L-1. At 98.3%, the melting point is 10℃; the boiling point is 338℃. Sulfuric acid is a strong acid with a high boiling point and low volatility. It is easily soluble in water and can be miscible with water in any ratio. Concentrated sulfuric acid releases a large amount of heat when dissolving, so when diluting concentrated sulfuric acid, "the acid should be added to the water, poured slowly along the wall of the container, and stirred constantly."

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