why doesn't blood rust?
364252
Blood does not contain enough iron to rust (rust is FeO2).  Rust is caused by the synthesis reaction:\n\n             Fe  +  O2 -------> FeO2\n\nWithout the right circumstances this will not happen, the right circumstances being that there be enough iron there for the reaction to occur.
254607
A metal's corrosion (rusting) rate depends on its chemical properties. Some metals just take longer than others to corrode. Keep in mind that most metals have very high melting temperature, so in general high temperature doesn't contribute to the corrosion of a piece of metal just sitting in a damp space. For temperature to be of concern, it has to be around 700 degrees Celsius.\n\nI don't know much about your experiment, but you might not be using an appropriate metal sample. Most commonly found metals come with coatings or contain chemical inhibitors to prevent corrosion. Think about bikes sitting in outside in a humid (moisture-rich) environment. Manufacturers have to coat the metals to prevent this corrosion, or else no one would buy their product. This is the case with most metals. So if you just picked up something laying around the house and tried to corrode it, your experiment might not be successful. You should also be aware that only ferrous (iron) alloys rust, and the particular metal you tested might be something else.\n\nGo to google and type "rusting metal" (without the "s). The first four sites have lots of info.\n\n*It wouldn't rust in the freezer because there's no moisture in the freezer.
501395
The colour of the blood underwater is moreover black. The reason behind it is- Red colour of blood is due to presence of oxygen. Thus heamoglobin at this moment is called oxy-haemoglobin. and its colour is red. When under water the amount of Oxygen is less and thus colour becomes more of blackish due to accumulation of CO2 and other gases along with hormones.
783824
Rusting or corroding is the wearing away of a metal layer that leads to formation of metal compounds on the surface. Rust is a compound that forms on top of iron. Blackening of silver is another example
821724
Rusting of iron is an oxidation/reduction process which means there is a transfer of electrons.  Any soluble ionic compound will facilitate the transfer of the electrons and accelerate the oxidation process.
686818
stainless steel is rust proof anyway, to do this, zinc is added during the smelting process, this creates a coating over the metal and when it comes into conntact with oxygen and water it forms a clear oxide layer over the metal, hence stopping the steel from rusting
100074
"rusts" are actually metallic oxides. Ferrous oxide is reddish brown. Zinc oxide is white. Aluminum oxide is whitish gray.
730355
Why not? Iron and oxgen form a number of compounds of both determinate and indeterminate composition. Someone want to give me the exact formula for rust?
67959
Oxygen in the atmosphere reacts with iron to oxidize it in what is called a redox reaction (oxidation/reduction).  The redox reaction is defined by the exchange of electrons--uncharged iron will lose two electrons to an oxygen molecule, creating iron oxide.  Water quicken rusting by serving as a catalyst.  Dissolved oxygen in the water reacts, and as the water dries, the oxygen becomes increasingly concentrated.\n\nShips will prevent wide-spread rusting by creating what is called a "sacrificial anode."  You might know the names anode and cathode from the ends of a battery.  Batteries function by employing two seperate redox reactions, where one end corrodes to release electrons, which travel to the other end and react with metal cations in solution, turning them to a solid metal.  In the case of ships, the corrosion of iron is prevented by creating a sacrificial anode out of something even more reactive than the iron (usually magnesium, if memory serves).  The corrosion of the magnesium releases excess electrons in the iron, which delays corrosion of the iron--oxyegn can grab the free electrons created by the corrosion of magnesium without needing to corrode the iron.\n\nI would imagine that the quickening of the rusting process cause by a scratch in the tin is due to the fact that the corrosion becomes concentrated in a single place.  The scratch likely serves as the "sacrificial anode" for the rest of the can.
964591
It's an iron oxide and it forms in an oxidising environment. Rich deposits may be the result of weathering, or precipitation out of oxygen-rich surface water or oxygen-rich water in hydrothermal veins.\n\nAs to why it is sometimes red and sometimes metallic-grey I'd say it is probably due to the size of the crystals. When it is ground up fine, it is always red. The smaller grains scatter red light.
760471
See a doctor, black stuff could be stale blood. Stale blood can be a good media for bacteria to breed.
181969
It loses electrons, so it gets a higher oxidation state. An example would be iron going to rust (Fe(s) --> Fe+3).
61979
Real rust is oxidized iron and so it can only be one color.
550059
Rust is the substance formed when iron compounds corrode in the presence of oxygen and water. It is a mixture of iron oxides and hydroxides. Rusting is a common term for corrosion, and usually corrosion of steel.\n\nIron is found naturally in the ore haematite as iron oxide, and metallic iron tends to return to a similar state when exposed to air, (hydrogen, oxygen, nitrogen, etc.) and water. This corrosion is due to the oxidation reaction when iron metal returns to an energetically favourable state. Energy is given off when rust forms. The process of rusting can be summarized as three basic stages: The formation of iron(II) ions from the metal; the formation of hydroxide ions; and their reaction together, with the addition of oxygen, to create rust.\n\nIron is the main component of steel and the corrosion of steel is observed more frequently, since iron is rarely used without alloying in the present day.\n\nWhen steel contacts water, an electrochemical process starts. On the surface of the metal, iron is oxidized to iron(II):\n\n    Fe → Fe2+ + 2e−\n\nThe electrons released travel to the edges of the water droplet, where there is plenty of dissolved oxygen. They reduce the oxygen and water to hydroxide ions:\n\n    4e− + O2 + 2H2O → 4OH−\n\nThe hydroxide ions react with the iron(II) ions and more dissolved oxygen to form iron oxide. The hydration is variable, however in its most general form:\n\n    Fe2+ + 2OH− → Fe(OH)2\n    4Fe(OH)2 + O2 → 2(Fe2O3.xH2O) + 2H2O\n\nHence, rust is hydrated iron(III) oxide. Corrosion tends to progress faster in seawater than fresh water due to higher concentration of sodium chloride ions, making the solution more conductive. Rusting is also accelerated in the presence of acids, but inhibited by alkalis. Rust can often be removed through electrolysis, however the base metal object can not be restored through this method.
56292
Rust is usually defined as a red or brown oxide coating on iron or steel caused by the action of oxygen and moisture. So rust is defined by the oxide coating. There are also methods of corrosion that involve things other than oxygen, but I don't think it would be classified as rust.
150659
You may be referring to a sacrificial anode?\n\nSometimes, in order to prevent something from rusting (like a metal water pipe or the hull of a ship), you sacrifice a more reactive metal to corrode first.\nFor example, if you wanted to protect an Iron water pipe from rusting, you could electrically conect it to a "sacrifical" piece of Magnesium (a more reactive metal)m this way, the Mg will corrose first, keeping the Iron safe.\n\nEdit:\nYou wouldnt mix the sacrifical metal in with the metal your trying to protect, then you'll just get an object with a bunch of holes in it (where the other metal was eaten away).  You would electrically connect the sacrifical electrode to the other metal with a wire or something of that sort, then as the sacrificial electrode is corroded away, the other metal stays perfectly intact.\nI think in real life Magnesium is a very common metal to use since it is so high up in the reactivity series and not insanely expensive. Silver doesnt corrose very much at all, it wouldnt work as a sacrifical electrode, not would it need one very badly.
325000
If the rim is all aluminum or all chrome it won't rust if they are just plated with aluminum or chrome then it depends if the surface metal was scratched off.