Homework Help

How does rust form?

user profile pic

cheyennerusse... | Student, Grade 9 | eNotes Newbie

Posted February 18, 2010 at 5:32 AM via web

dislike 2 like

How does rust form?

3 Answers | Add Yours

user profile pic

marbar57 | Elementary School Teacher | (Level 3) Associate Educator

Posted February 18, 2010 at 8:10 AM (Answer #1)

dislike 2 like

Rust is a common term used for the corrosion of iron and its alloys (i.e. steel), formed by the reaction of the iron with oxygen.  Given sufficient time, oxygen, and water, any iron mass eventually converts entirely to rust and disintegrates. 

The rusting of iron is an electrochemical process in which electrons are transferred from iron to oxygen.  The result is a reddish-brown residue produced by the breakdown of the iron molecules.  If allowed to progress, it eventually compromises the integrity and strength factor of the iron mass to the point where breakage or failure can occur. 

Rust is a serious, often dangerous factor to contend with when building large metal structures!  So, many anti-rust agents have been developed over the years to apply to iron-containing metals in an effort to slow down or prevent rust's occurrence.  Such products or agents include, but are not limited to:  rust-inhibiting paint, polymer coatings, zinc and tin electroplating, bluing, and dehumidification. 

On small metal surfaces, rust can be removed by the application of steel wool or various other metal polishing compounds (i.e. WD-40).  With a little time and "elbow grease", a shiny surface can usually be restored to its original luster.

user profile pic

amarang9 | College Teacher | (Level 1) Educator Emeritus

Posted February 18, 2010 at 9:02 AM (Answer #2)

dislike 1 like

Rust is an iron oxide, the result of a chemical process: the interaction between a metal like iron (Fe) and Oxygen (O) while in the presence of water (H2O) or moisture in the air. It is a transfer of electrons from Iron to Oxygen. In the reaction, Iron is oxidized, which means it loses electrons (a gain, because losing negative particles like electrons results in an increase in positivity +). The Oxygen molecules gain electrons and therefore are reduced, since they have gained negative particles. The rust particle itself is most commonly FE2O3. Other elements like electrolytes, calcium , acid, or salt, by itself or as salt-water, can speed up the process. Water functions as the electrolyte, something that frees electrons.

Essentially what happens is that the freeing of the Iron electrons breaks the iron down: the water provides oxygen to the iron, iron electrons are freed, and the freed iron particles combine with the oxygen (from water) to make iron oxide (Fe2O3).The freed iron and oxygen combine and are essentially swept away (think of rust flaking off) in this electrochemical flow.

 

user profile pic

krishna-agrawala | College Teacher | (Level 3) Valedictorian

Posted February 18, 2010 at 12:27 PM (Answer #3)

dislike 1 like

Rust consists of the compound iron oxide which is formed on the surface of iron and steel exposed of moisture and air. Rust is formed by the process of oxidation of iron, that is, iron combining with oxygen to form oxides of iron.

The process of rusting of Iron can be reduced or eliminated by different methods as keeping the iron in dry atmosphere. coating it with some protective layer of other materials such as oil, chromium or zinc, and allowing iron with other metals to make rust resistant alloys such as stainless steel.

Join to answer this question

Join a community of thousands of dedicated teachers and students.

Join eNotes