UC

Well, the nitrating mixture is acidic, is it not? And sodium benzoate would become what when exposed to a strong acid? With that nudge, you should be able to answer the question.

Easy. Phenylthiourea. Also, still looking for an answer for mine.

http://en.wikipedia.org/wiki/Depletion_gilding Nitric acid isn't magical and able to penetrate solid materials, so you'll only remove what little is on the surface, building up an impenetrable layer of pure gold Have a look at this. By diluting the gold with silver (which is susceptible to nitric acid), you can penetrate the entire solid and leave behind only gold and other metals that do not dissolve in nitric acid: Plenty of reading material here: http://goldrefiningforum.com/

Is it unusually light or unusually heavy for it's size? Galena (PbS) looks an awful lot like silicon except for it's density. Silicon is oddly lightweight. Value depends entirely on purity and since we humans make vast quantities of ultrapure (99.9999+%) silicon for electronics it's value won't be terribly high in any case. More likely it is of lower purity from an earlier stage of refinement- at worst about 98%. You wouldn't be able to get more than a few dollars for it without knowing and even the ultrapure material wouldn't get you much more. If it's galena, it won't be too valuable anyway as it is a fairly common mineral.

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*slow claps*

Clearly alchemy is the answer. Into a large earthenware vessel, place a synthetic plastic card, known as a credit card. Take care in writing down the numbers engraved upon it. Upon the device known as a computer, find a website that sells the caustic that you seek- perhaps for making soap or bio-diesel. Enter unto the named boxes the numbers of the plastic card, checking carefully. If thou shalt fail in this step, the transformation shall not be completed. Enter also your name and address as required and press upon the button marked "order." Allow the card to remain in the earthenware vessel for 3-10 days until the messenger of the winds delivers unto you a brown vessel containing the caustic that you desired.

H2O2 is a relatively poor antibacterial at low concentrations, IIRC. H2O2 injection combined with ozonolysis is much more effective IIRC as it generates free hydroxyl radicals. This however is probably quite a bit pricier than the old standby chlorine (or chloramine treatment)

That specific grignard cannot be prepared. The reaction instead proceeds by the formation of ethylene and 1 equivalent of magnesium bromide. In fact 1,2-dibromoethane is a common initiator for sluggish grignards because the product removes itself from the reaction mix as visible bubbles.

Cyrogenic oxygen storage has significant hazards related to tank rupture necessitating very heavy tanks. The candles are lighter and could easily stand severe pressure changes, but poor storage/manufacturing/handling might cause explosions. Tough call. My vote would be for the candles. http://en.wikipedia.org/wiki/Chemical_oxygen_generator

Largely practical knowledge. For example, NO2 solvated in water disproportionates to give nitric acid and nitric oxide. [ce] 3NO2 (aq) + H2O (l) -> 2HNO3 (aq) + NO (g) [/ce] Almost everything is explainable in terms of lewis acid-base interactions, and electronegativity can help steer reaction predictions, but guarantees nothing. For example, sulfur tetrafluoride is a toxic gas that reacts violently with water. Sulfur hexafluoride is a dense, essentially inert gas.

Nickel is much lower on the electromotive series than zinc, and the reaction is less energetically favorable- in other terms, slower. Outside or in a fume hood, you could add nitric acid or sodium nitrate (though you will need to remove the sodium chloride from the product) to make the oxidizing mixture known as aqua regia (or poor man's aqua regia for the sodium nitrate version, potassium nitrate would be okay as well- don't use ammonium nitrate). This gives off all sorts of nasty fumes (hence outside), but will even dissolve gold, which normally does not react at all with hydrochloric acid.

Does it make any sense that a 50ppm solution of a complex is 391.5ppm of iron?

Photoshop.

http://en.wikipedia.org/wiki/Oxygen See the thing on the right that says freezing point? That's for atmospheric pressure. Mercury is regularly distilled to purify it. Good reagent grade material is triple-distilled. Iron can certainly be vaporized, but would react readily with oxygen if not under vacuum or inert gas blanket. http://en.wikipedia.org/wiki/Iron Same deal. Note how extremely high the temperature is. This would probably best be done using an electric arc furnace.

Think of a solution as ion soup. You're making tetraamminecopper(II) ions, so the anion doesn't really matter- unless it causes the complex to precipitate. If a copper salt is insoluble but its tetraammine form is, the solid will slowly dissolve in the ammonia.

Have you considered that maybe you're just good at failing?

You'd be better off with a solution of bromine in a pressure equalizing dropping funnel. Appropriate solvents would be glacial acetic acid, chloroform, or dichloromethane, depending on the reaction solvent. You can always add it straight in under strong stirring, but you'll need better control over the flow rate than for solutions.

Bromobenzene is just a high temperature solvent. It's a diels-alder followed by extrusion of CO. Can you draw a mechanism?

It doesn't decompose, it more or less evaporates if you run out of liquid completely, which I don't recommend. Stop reasonably before that and chill, then filter off crystals.

A *sealed* bag for an aqueous solution? That's a *lot* of CaCl2 and effort for a small amount of ammonium chloride. You're better off evaporating the solution with a hot plate or just by air exposure (very slow) and then cooling it. ammonium chloride is very soluble in water and when concentrated, the vapor pressure of the solution is very low. About 2 years ago, I neutralized almost a gallon of 5% ammonium hydroxide with a slight excess of HCl, and left the solution in a cut-off polyethylene milk jug with paper towels over the top to keep out dust and bugs. The heat in the summer evaporated much of the liquid, and when winter came, the very gradual onset of cold precipitated out gorgeous crystals of ammonium chloride. I filtered these off and left the wet, somewhat acidic NH4Cl in a dessicator over NaOH pellets, which do double duty of trapping the water vapor and excess HCl. Since I've lowered the concentration by removing crystals and increased the vapor pressure, after the coming summer, I should be able to harvest another crop. Sure, I could do it with a hotplate and be done in a day or two, but where's the fun in that

Uh, I don't know how easy A. Niger would be to get a culture of. The balanced reaction may look simple, but it's carefully controlled in steps by enzymes. Burning sugar or anything of the sort would produce precisely a mess. That process is also thermodynamically downhill, so there's a nice payoff of ATP for the organism, I suspect.

That sounds like a question for a very specific area of literature ...or some samples, a muffle furnace, and atomic emission spectrometer.