in a fire assay for gold what is the best way to overcome the effect of ilmenite and iron in the crucible?
452626
The answer seems to be to mix the gold with silver and wrap it in aluminum foil, thus eliminating the possibility of contamination.\n\nSee: http://www.gold.org/jewellery/technology/assay/
114729
<flame test, test used in the identification of certain metals. It is based on the observation that light emitted by any element gives a unique spectrum when passed through a spectroscope. When a salt of the metal is introduced into a Bunsen burner flame, the metallic ion produces characteristic color in the flame. Some metals and the colors they produce are: barium, yellow-green; calcium, red-orange; copper salts (except halides), emerald green; copper halides or other copper salts moistened with hydrochloric acid, blue-green; lithium, crimson; potassium, violet; sodium, yellow; and strontium, scarlet. The value of this simple flame test is limited by interferences (e.g., the barium flame masks calcium, lithium, or strontium) and by ambiguities (e.g., rubidium and cesium produce the same color as potassium). A colored glass is sometimes used to filter out light from one metal; for instance, blue cobalt glass filters out the yellow of sodium.\n\n<The flame test is a procedure used in chemistry to detect the presence of certain metals. It involves introducing a sample to a flame, and observing the color that results. The test is based on the fact that each element has its own characteristic emission spectrum. Samples are often held on the looped end of a clean, nonreactive wire (it's best with platinum or gold, although nichrome is used as a substitute) or on the tip of a wood stirring stick soaked in water. Sodium is a common component or contaminant in many compounds and its spectrum tends to dominate over others. The test flame is often viewed through cobalt blue glass to filter out the yellow of sodium and allow for easier viewing of other metals.\n\nThe main advantage of the flame test is that it is fast and easy to conduct, and does not require any special equipment. However, the range of detected elements is small, and the test relies on the subjective experience of the experimentalist than any objective measurements. The test has difficulty detecting small concentrations of some elements, while too strong a result may be produced for certain others, which tends to drown out weaker signals. Finally, the test only gives qualitative information, not quantitative data about the actual proportion of elements in the sample.
548563
try Zinc.....sacrficial protection (galvanizing)\n\nyou can also use aluminium, it will react at first but then it will form a tough protective layer of aluminium oxide, which prevents further reaction....it really works
652769
Galvinisation with zinc. \n\nChroming\n\nboth work off the basis of reduction and their poteintal to be oxidised\n\nlook in an chemistry A-Level text book. Or if your american look at a college text book, for exact details
791597
You will get Silver Chromate as the precipitate.  It is red in color.\n2AgNO3(aqueous) + K2CrO4(aqueous) -> Ag2CrO4(solid) + 2KNO3(aqueous)
155392
One method is using bimetallic strips of metals that can stand very high temperature. Bimetallic strips bend when the temperature changes.
174049
I'd like to encourage you to learn chemisrty instead. The alchemists tried and tried to make lead into gold and similar things. Now we know that it cannot be done. They wasted their time. Don't waste yours. Learn and make something of yourself.
125282
Most efficient? If you don't have a lab, then I would assume just doing your best at grinding off the top layer, and trying to melt the shreddings down into a >70% gold alloy. Since gold's melting point is OVER 1000 degrees Celsius, I suppose your best bet is to heat the grindings as much as possible, and then pounding them together into a single mass (like a black-smith...or 'gold-smith'). But you have to realize HOW LITTLE gold is actually on there. The layer is so thin...sometimes merely 2-3 micrometers. You're gonna get a lot of impurities, such as nickel and copper. Gold-plating is usually done on copper or silver; and in the case of copper, a thin layer of nickel is placed below the gold. And since the melting point of nickel isn't that far from that of gold, and copper's is almost EXACTLY that of gold's, you're gonna get a random mixture of crap. I imagine the process is more trouble than it's worth. I'd just go buy gold from alfa aesar or somewhere like that for cheap-as-free.
157730
I think FePO4 +O2 >>>>> Fe2O3 + PO2. balance it and solve it . n its simple stoichiometry.
1096251
One easy quick & easy way to find out is the streak test. Rub the mineral in question across an unglazed porcelain tile. If the streak it makes is black then it is pyrite (fool's gold). If it is golden yellow then you have gold. You can find these tiles in your local home & garden shop or hardware store.\n\nAnother simple one is the hardness test. Gold has a hardness of 2.5 to 3 on Moh's Scale. Pyrite is 6 to 6.5. Glass has a hardness of about 5.5. According to Moh's scale you should be able to scratch glass w/ pyrite but not w/ gold. Pennies can also be used as their hardness is about 3.5.\n\nGold is found in several different forms or habits. It can be dendritic (vein-like) or massive as in nuggets. Upon examining pyrite more closely (perhaps w/ a 10x magnifier) you will see that while it resembles a gold nugget it is actually made up of many tiny little cubes.\n\nGold will not cleave whereas pyrite will. Cleavage is simply how a mineral breaks evenly due to weaknesses in its crystal structure. Pyrite has cubic cleavage so that when it is hammered it will come apart in perfect little cubes.
232646
Fire is oxidation of a material at a fast rate. The aluminum foil you put in the stove getx a coat of aluminum oxide on it and then goes no further as a gas oven is not hot enough to "burn" aluminum. Aluminum can be burned if one gets the temperature hot enough. This is called the thermite reaction and happens when finely divided aluminum, such as shavings is mixed with iron oxide (rust) and the mixture set afire with a fuse perhaps made from thin strips of magnesium metal. The iron oxide or rust becomes iron metal again and the aluminum becomes aluminum oxide or alumina. The heat is intense enough to melt iron.Such reactions are used in industry to perform welding. It is all quite dangerous and a person not familiar with the laws of chemistry may become blinded by the light of the reactions involved or harmed by server burns. Do not try this at home.
1099415
I don't know how you are precipitating out the gold, but I don't think a colorimetric test for gold in solution is possible.  It is non-reactive and does not ionize.  Given that gold has filled upper electron orbitals, you might be able to run a UV-VIS spectrum and get some UV absorption for solvated gold versus clean aqua regia.  The UV apsorption is probably going to be in the lower UV wavlengths, and it might not be possible to differentiate between trace levels of gold and trace levels of transition metal impurities.\n\nIf you are precipitating the gold by an equilibrium process, just load up on your precipitation compound to push the equilibrium as far as possible to one side.  Another possibility is to electrolytically remove any trace gold from the aqua regia.  Sorry I don't have any better suggestions.
417868
Your best bet would be to use water and make a salt water solution.  Using a magnet would work well unless you had a lot of iron fillings together and they were under some salt and all of them were pulled out of the mixture.  Then you would still have salt with the iron.  \n\nMake a aqueous(with water) solution, filter, and allow the water to evaporate.
896646
"The final experiment was to observe the reaction when one small crystal of NH4SCN was added to 0.1 M FeCl3. The color of FeCl3 was yellow, but after NH4SCN was added, the color of contents changed to red.\nIn second experiment, when the Mg was ignited, the resulting flame was hot. Therefore, the release of thermal energy through the interaction of Mg and O was shown.\nFiguring out the type of the last two reactions was difficult, because the chemical equations were not given. However, the possibility that the type of both reactions were replacement reactions was high. The reason being that the chemical reactions were observed as a color change and this means that the composition of the substance is changed.\nThis experiment was very successful, and it was a good opportunity to observe chemical reactions directly."\n\nI would change your paragraph to that.  I would also expand on the other experiments if you know more about them.
958410
1.\nMn(s) + SnCl2(aq) --> MnCl2(aq) + Sn(s)\nCr(s) + 2HBr(aq) --> CrBr2(aq) + H2(g)\nCo(s) + CaBr2(aq) --> N.R\n2Al(s) + 3Ni(NO3)2(aq) --> 2Al(NO3)3(aq) + 3Ni(s)\n\n2.\nMg + 2AgNO3 --> Mg(NO3)2 + 2Ag\nmole of Ag = 3.580 / 108 = 0.033 mole\nmole of AgNO3 = 0.033 mole = 33 mmole\nmolarity of AgNO3 = 33 / 50 = 0.66 M\n\n3.\na.soluble\nb.soluble\nc.soluble\nd.insoluble\ne.soluble\nf.soluble\ng.insoluble in water, soluble in acid\nh.soluble\n\n4.\n3NaOH(aq) + Fe(ClO4)3(aq) --> Fe(OH)3(s) + 3NaClO4(aq)\n3Na+ + 3OH- + Fe3+ + 3ClO4- --> Fe(OH)3 + 3Na+ + 3ClO4-\nFe3+ + 3OH- --> Fe(OH)3\n(NH4)2SO4(aq) + Pb(NO3)2(aq) --> PbSO4(s) + 2NH4NO3(aq)\n2NH4+ + SO42- + Pb2+ + 2NO3- --> PbSO4 + 2NH4+ + 2NO3-\nPb2+ + SO42- --> PbSO4\n\nHope it helps\npeace\nvixklen
225339
When you heat something in porcelain crucible, it may react with it, or stay in the crucible for some reason. When you heat the porcelain crucible, you can clean it for the next reaction so your next reaction would not be affected by the chemicals in the crucible from the last experiment. Also don't forget to do that in a closed and well ventilated area.
957199
If you are doing it in a laboratory setting, you can mix it with carbon and reduce it to the metal. You will need high temperatures, though.