Why do acids corrode

Acid corrosion of stone and metal. Authors Authors and affiliations Heather A. How to cite. This is a preview of subscription content, log in to check access. Goudie, A. The Human Impact. This can be a crystal formation that develops as a material begins to solidify, or what occurs as a gas transitions to its liquid form.

Nucleation is important for understanding metals and crystallization. View Full Term. By clicking sign up, you agree to receive emails from Corrosionpedia and agree to our Terms of Use and Privacy Policy. Acidic corrosion occurs in stone and metals that are prone of high salinity, chemicals, low oxygen and harsh environmental operating conditions.

Acidic corrosion is a gradual destruction and wearing away of a material e. The acids may be those coming from soil, industrial air, water or toxic chemicals that react with the material they contact. The cause of acidic corrosion in industrial equipment is due to an electrochemical reaction.

Three conditions must exist:. The major classes of corrosive chemicals are strong acids and bases, dehydrating agents, and oxidizing agents. Some chemicals, such as sulfuric acid, belong to more than one class. In addition many corrosives have other hazards such as reactivity e.

The strength of acids and bases is defined as the degree of ionization of the acid or base in water. The inorganic or mineral acids, such as hydrochloric acid, a strong acid, generally ionize more than the organic acids, such as acetic acid, a weak acid. Similarly, sodium hydroxide is highly ionized and classified as a strong base, whereas ammonium hydroxide is slightly ionized and characterized as a weak base.

The concentration of the acid or base, which is unrelated to its strength, refers to the percentage of the chemical dissolved in water. The corrosivity of acids and bases is dependent on their strength and concentration. Dehydrating agents, such as sulfuric acid, sodium hydroxide, calcium oxide, and glacial acetic acid, are corrosive because of their strong affinity for water.

This reaction with water is extremely exothermic. Because of this exothermic reaction with water, concentrated acids should always be added slowly to water. If water is added to the concentrated acid, the rapid generation of heat can cause the water to vaporize, causing the hot concentrated acid solution to splash. Many oxidizing agents such as halogens, peroxides, nitric acid, and chromic acid are also corrosive, in addition to their fire and explosion hazard.

Corrosives can damage human tissue in their solid, liquid and vapor state. Acute hazards can be manifested as burns, ulceration, permanent tissue damage, or toxic effects. Many corrosives also have chronic hazards, as repeated exposure to even dilute solutions or vapors can cause dermatitis, bronchitis, or eye damage.

Acid burns are generally perceived as more painful, which is due to the formation of a protective protein layer which resists further penetration of the acid. In fact, tissue damage from bases is often more serious, as no protective layer is formed and the injury penetrates deeper. The destructive effect of corrosives is greatly increased when they are used at elevated temperatures. In addition to the health hazards, the physical hazards posed by many corrosives must also be remembered.

For example, many inorganic acids release flammable hydrogen gas when in contact with metals, posing a serious fire and explosion hazard. The following are examples of some of the hazards of commonly used corrosives. The list is by no means exhaustive. The hazards of each corrosive should be thoroughly investigated prior to its use. Sulfuric Acid is a strong acid, a dehydrating agent, and an oxidizing agent when heated. Is HF a strong acid? Why does neutralization occur? Do strong acids completely dissociate in water?

How can I calculate pH of weak acid? See all questions in Acids and Bases.