Type of corrosive substance and uses info Chemical Man

A corrosive substance is one that will destroy and damage other substances with which it comes into contact. It may attack a great variety of materials, including metals and various organic compounds, but people are mostly concerned with its effects on living tissue: it causes chemical burns on contact and can lead to complications when ingested.

Common types

Common corrosive chemicals are classified into:

    Acids
        Strong acids – the most common are sulfuric acid, nitric acid and hydrochloric acid (H2SO4, HNO3 and HCl, respectively).Some concentrated weak acids, for example formic acid and acetic acid.Strong Lewis acids such as anhydrous aluminum chloride and boron trifluoride.Lewis acids with specific reactivity; e.g., solutions of zinc chloride  Extremely strong acids (superacids)

    Bases
        Caustics or alkalis, such as sodium hydroxide, potassium hydroxide, and calcium hydroxide Alkali metals in the metallic form (e.g. elemental sodium), and hydrides of alkali and alkaline earth metals, such as sodium hydride, function as strong bases and hydrate to give caustics. Extremely strong bases (superbases) such as alkoxides, metal amides (e.g. sodium amide) and organometallic bases such as butyllithium.Some concentrated weak bases, such as ammonia when anhydrous or in a concentrated solution.Dehydrating agents such as concentrated sulfuric acid, phosphorus pentoxide, calcium oxide, anhydrous zinc chloride, also elemental alkali metals.

    Strong oxidizers such as concentrated hydrogen peroxide.

    Electrophilic halogens: elemental fluorine, chlorine, bromine and iodine, and electrophilic salts such as sodium hypochlorite or N-chloro compounds such as chloramine-T; halide ions are not corrosive, except for fluoride.

    Organic halides and organic acid halides such as acetyl chloride and benzyl chloroformate.
    Acid anhydrides
    Alkylating agents such as dimethyl sulfate
    Some organic materials such as phenol ("carbolic acid")

Uses

Some corrosive chemicals are valued for various uses, the most common of which is in household cleaning agents. For example, most drain cleaners contain either acids or alkalis due to their capabilities of dissolving greases, proteins or mineral deposits such as limescale inside water pipes.

In chemical uses, high chemical reactivity is often desirable, as the rates of chemical reactions depend on the activity (effective concentration) of the reactive species. For instance, catalytic sulfuric acid is used in the alkylation process in an oil refinery: the activity of carbocations, the reactive intermediate, is higher with stronger acidity, and thus the reaction proceeds faster. Once used, corrosives are most often recycled or neutralized. However, there have been environmental problems with untreated corrosive effluents or accidental discharges.