Well, Gib a three word sentence is a long one for you-lol. I have to guess. I think I have read somewhere that chromium can be subsituted for nickel, but I do not really understand that at all. I do nto even know what the price of chromium is. I am guessing it is rust resistant.
That is an interesting subject of which I know nothing.
I think a lot of us thought when the sudbury strike ended the hedge funds and momo players would sell nickle off, but it did not happen, thus the relevance of the $550 per ton rise in nickel last week.
ssentials
Name: chromium
Symbol: Cr
Atomic number: 24
Atomic weight: 51.9961 (6)
CAS Registry ID: 7440-47-3
Group number: 6
Group name: (none)
Period number: 4
Block: d-block
Description
Here is a brief description of chromium.
Standard state: solid at 298 K
Colour: silvery metallic
Classification: Metallic
Availability:
This sample is from The Elements Collection, an attractive and safely packaged collection of the 92 naturally occurring elements that is available for sale.
Chromium is steel-gray, lustrous, hard, metallic, and takes a high polish. Its compounds are toxic. It is found as chromite ore. Siberian red lead (crocoite, PrCrO4) is a chromium ore prized as a red pigment for oil paints.
WebElements movies
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The picture above shows the result of burning ammonium dichromate, (NH4)2Cr2O7, containing pellets of mercuric thiocyanate (HgCNS). This is a large scale version of the indoor firework "Serpents in te grass". Do not attempt this reaction unless are a professionally qualified chemist and you have carried out a legally satisfactory hazard assessment. Improperly done, this reaction is dangerous! Select a movie icon to see the volcano and serpents (lighting not great - sorry).
Nearing Zero cartoon included by kind permission of Nick Kim.
Emerald is a form of beryl (a beryllium aluminium silicate) which is green because of the inclusion of a little chromium into the beryl crytal lattice in place of some of the aluminium ions. Similarly, traces of chromium incorporated into the crystal lattice of corundum (crystalline aluminium oxide, Al2O3) as a replacement for some of the Al3+ ions results in another highly coloured gem stone, in this case the red ruby.
Isolation
Here is a brief summary of the isolation of chromium.
It is not normally necessary to make chromium in the laboratory as it is so readily available commercially. The most useful source of chromium commercially is the ore chromite, FeCr2O4. Oxidation of this ore by air in molten alkali gives sodium chromate, Na2CrO4 in which the chromium is in the +6 oxidation state. This is converted to the Cr(III) oxide Cr2O3 by extraction into water, precipitation, and reduction with carbon. The oxide is then further reduced with aluminium or silicon to form chromium metal.
Cr2O3 + 2Al ? 2Cr + Al2O3
2Cr2O3 + 3Si ? 4Cr + 3SiO2
Another kind of isolation is by electroplating processes. This involves the dissolution of Cr2O3 in sulphuric acid to give an electrolyte used for chromium electroplating. |
