Chromium is a steel-gray, lustrous, hard metal that takes a high polish, and melts with difficulty. Its tendency to oxidize causes it to tarnish.
The most common oxidation states of chromium are +2, +3, and +6, with +3 being the most stable. +4 and +5 are rare. Chromium compounds of oxidation state 6 are powerful oxidants.
Chromium(0) is unstable in oxygen, immediately producing a thin oxide layer that is impermeable to oxygen and protects the metal below.Applications:
metallurgy, to impart corrosion resistance and a
- as an alloy constituent, such as in stainless steel in cutlery
- in chrome plating,
- in anodized aluminium, literally turning the surface of aluminium into ruby.
- As dyes and
- Chromium(III) oxide is a metal polish known as green rouge.
- Chromium salts color glass an emerald green.
- Chromium is what makes a ruby red, and therefore is used in producing synthetic rubies.
- As a catalyst.
- Chromite is used to make molds for the firing of bricks.
- Chromium salts are used in the tanning of leather.
- Potassium dichromate is a chemical reagent, used in cleaning laboratory glassware and as a titrating agent. It is also used as a mordant (i.e., a fixing agent) for dyes in fabric.
- Chromium(IV) oxide (CrO2) is used to manufacture magnetic tape, where its higher coercivity than iron oxide tapes gives better performance.
- In well drilling muds as an anti-corrosive.