What are 2 things that make iron rust?

Answer 1

Oxidation

Answer 2

Corrosion: When iron is exposed to water and oxygen, it corrodes. The corrosion products are the familiar red-brown rust. Indoors, a certain amount of moisture in the air (above about 65% relative humidity) is usually required before iron will rust. However, corrosion may occur at lower relative humidity if the object's surface is contaminated with salt, dust, or other pollutants. Some iron objects have acquired an adherent rust layer from past exposure to high levels of moisture. This rust layer is often stable and will help slow corrosion of the underlying metal if the object is accidentally exposed to high moisture levels. Salt or other contaminants in the rust layer will stimulate further corrosion, especially at higher relative humidity. A sign of ongoing corrosion is flakes or loose powdery rust surrounding an object.

Salts and oils on the skin can produce exactly the kind of corrosive environment that causes iron to react. Also, exposure of iron objects to cooking materials such as salts and sauces can accelerate corrosion. If the iron object in question is considered valuable, it should not be used as it was in the past. It should be protected from excessive handling and kept in a dry location. Attics, basements and garages are not good places to store iron objects because of fluctuating environmental conditions.

Iron has been used for several thousand years in many different forms. It can be wrought by hand, cast into moulds, or formed through a wide range of modern factory processes. It is the most common metal in collections and appears universally in every household.

All common metals are derived from their natural ores by a process called smelting. Iron ores are very stable chemical substances, but when smelted a great deal of energy is put into them to produce the metal. The metal is, therefore, more reactive and less stable and would return to the stable state if it could. We know by observation that metals are relatively unstable - they will rust and tarnish if allowed to do so. This process is called oxidation, although it is not always oxygen that is responsible. As iron oxidizes it moves quite slowly to states of lower energy where it is less reactive and thus more stable.

Iron is converted to steel by adding carbon or other trace elements. In fact, objects of pure iron are very scarce. Working iron during forging introduces carbon as a by-product, resulting in the production of steel. So even wrought iron objects made by blacksmithing are actually made of low carbon steel. Early smiths used this property to advantage, adjusting the amount of forging to make composite sword blades with hard edges and flexible cores. Cast iron objects actually contain quite a high proportion of carbon; as much as 4% in some cases. Thin sheet steel is one of the most common forms of iron, appearing in a wide range of artefacts from lamps and stoves, to cooking ware and containers. Steel is also plated with tin or zinc to give it better protection from the environment.

What Is Rust?

Many materials react with oxygen to form a chemical compound that is a combination of that material and oxygen. When iron combines with oxygen, it forms iron oxide, or rust. Iron oxide is a larger molecule than iron, so if iron oxidizes, it often puffs up and may even flake. This is because the rust requires more physical space than the original iron.

Some things cause steel or iron to rust faster than others. Water will cause iron and steel to rust. Dissimilar metals rust faster than single metals because of electrochemical reactions, so steel rusts faster than iron, and joints between dissimilar metals rust very quickly. Salt water will cause rust faster than water because salt water is a better electrical conductor. Like most chemical reactions, heat also speeds rust.

If steel starts to rust, it will puff up because iron oxide is a larger molecule than iron. The puffing causes cracks and voids, which expose more bare metal to the environment. So the rusting of iron can progress and is only limited by destruction of all solid iron. Other metals oxidize, but the oxides of some other metals are no larger than the metal themselves, so they don't puff up or flake. For example, aluminum doesn't puff up when it oxidizes. This helps make aluminum oxide a good protective coating, rather than the start of rapid degeneration.

Rust is really Fe2O3, a reddish form of iron oxide. Iron has another oxide, Fe3O4, which is sometimes called black oxide, black rust, or hammer scale. Black oxide is a good protection for steel. Like aluminum oxide, black oxide molecules are the same size as iron molecules, so black oxide does not grow or flake. Black oxide is true gun bluing and the oxide found on some drill bits. Black oxide is also seen on iron and steel that has been hot-worked.

You can coat steel with black oxide by a careful regimen of rusting the right amount and boiling the rusted metal in water to convert it. This is how non-caustic gun bluing is done, and although it is tedious, it produces very attractive and durable results after several treatments.
The iron reacts with the oxtgen
The element iron "rusts" when it reacts with oxygen of the air, usually in the presence of water, to form a brown substance known as iron oxide. It is a slow chemical reaction which takes place over a period of time.

Rust is the common name for iron oxide. Iron oxide is comes in several forms. The most common are:

FeO ---- iron (II) oxide

Fe3O4 - iron (II,III) oxide

Fe2O3 - iron (III) oxide

As to why iron will rust, or put more chemically, why iron will oxidize :

Iron oxide has a lower free energy than do iron and oxygen. Just as a ball will roll downhill because it has a lower free energy at the bottom of the hill than at the top, iron will combine with oxygen - essentially 'rolling down a chemical reaction hill'. The reason things like water, salt, acids and other chemicals cause iron to rust faster, is that these substances act as catalysts to the oxidation reaction.

Practically all metals oxidize just like iron; however, usually this layer of oxide on the surface protects the rest of the metal. Aluminum objects, for example, all have a thin layer of Aluminum Oxide on the surface, protecting the rest of the metal from oxidation. With iron, the oxide layer happens to flake off or "exfoliate". This exposes new metal under the oxide layer and so it doesn't protect the metal like oxide layers do on other metals. So, iron doesn't rust because it oxidizes more easily than other metals. Aluminum actually oxidizes more readily than iron. But iron's oxide's layers flake off, so the metal isn't protected by it.

We can also say that the addition of water (hydration) is taking place, and as iron is a transition element, it has variable oxidation states. Before adding water, its oxidation state is +2 and after the addition of water it is a +3 state.
Oxidation via air and water.

Rust is caused by oxidation. If you take a piece of iron and you spray or paint it with a clear plastic then you are stopping the oxygen from getting to it. The result is that it can not rust.

Rusting of iron is a chemical process.Iron metals get rust on coming in contact with moist air and get corroded.the chemical reaction is represented as;

Fe+O2+H2O--Fe2O3.xH2O
iron reacts with oxygen to produce iron oxide known as rust coastal areas are more humid.so there is more moisture in the air.air with many oxygen which makes iron rust fastly.

Answer 3

Iron is a highly reactive metal and when exposed to air, water and moisture, it starts

reacting with them and forms rust.

Basically rusting is the reaction of iron with oxygen and iron is nothing but iron oxide(Fe2O3). Iron things can be protected from rusting by using paints, galvanization etc.

Answer 4

Factors that contribute to rusting include exposure to:

• air
• water
• time

Answer 5

These factors are: deffects on the surface of the sample, size and form of the sample, water, impurities in water, temperature, pressure, etc.

Answer 6

Oxygen and water and time