What makes rust form

Julie Richards is a freelance writer from Ohio. She has been writing poetry and short stories for over 30 years, and published a variety of e-books and articles on gardening, small business and farming. She is currently enrolled at Kent State University completing her bachelor's degree in English. How to Calculate the Area of Steel. How Does Rust Spread? Alodine Vs. The Manufacturing Process of Air Conditioners. Demagnetizing a Steel Nail. How to Make Rust Powder. How to Calculate a Circular Area.

Tin Oxide Removal. Why Do Pennies Corrode? How to Change the Color of Metal Surfaces. What Is Wrought Steel Pipe? List of Bacteria in the Temperate Deciduous Forest. Facts About Calcium Chloride. The Effects of Saltwater on Metals. Rust requires three chemicals in order to form: iron , oxygen, and water. This is an example of an electrochemical reaction and corrosion.

Two distinct electrochemical reactions occur:. There is anodic dissolution or oxidation of iron going into aqueous water solution:. Cathodic reduction of oxygen that is dissolved into water also occurs:.

The iron ion and the hydroxide ion react to form iron hydroxide:. The iron oxide reacts with oxygen to yield red rust, Fe 2 O 3.

Because of the electrochemical nature of the reaction, dissolved electrolytes in water aid the reaction. Rust occurs more quickly in saltwater than in pure water, for example. Keep in mind oxygen gas O 2 is not the only source of oxygen in air or water. Carbon dioxide CO 2 also contains oxygen. Carbon dioxide and water react to form weak carbonic acid.

Carbonic acid is a better electrolyte than pure water. As the acid attacks the iron, water breaks into hydrogen and oxygen. Free oxygen and dissolved iron form iron oxide, releasing electrons, which can flow to another part of the metal. Once rusting starts, it continues to corrode the metal. Rust is brittle, fragile, progressive, and weakens iron and steel. To protect iron and its alloys from rust, the surface needs to be separated from air and water.

Coatings can be applied to iron. Stainless steel contains chromium, which forms an oxide, much like how iron forms rust. The difference is the chromium oxide does not flake away, so it forms a protective layer on the steel. Actively scan device characteristics for identification. Use precise geolocation data. The chemical compounds found in liquids like acid rain , seawater and the salt-loaded spray from snow-belt roads make them better electrolytes than pure water, allowing their presence to speed the process of rusting on iron and other forms of corrosion on other metals.

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