jdurg

Cap'N's simplified explanation is pretty much spot on. Vapor pressure is simply a measurement of the pressure exerted by the vapor of a liquid. Volatility is a measurement of how readily a liquid turns into vapor. So if you know those two things you can understand how a substance with a higher vapor pressure will be more volatile than something that isn't. The substance with the higher vapor pressure has more of itself in the vapor phase exerting a pressure on the air around it. This means that more of it is evaporating at a given temperature than something which has a lower vapor pressure. As you raise the temperature, you always increase the vapor pressure. This is because you give more energy to the molecules and atoms at the surface of the liquid to escape from the liquid and become vapor. When something is boiling, it's vapor pressure is equal to the atmospheric pressure which means that the atmosphere is no longer able to exert a force on the liquid which makes it stay liquid. The molecules/atoms now have plenty of energy to break free from the liquid and become vapor since the atmosphere above it is no longer stopping it. Therefore, you can make a substance boil at a lower temperature by reducing the atmospheric pressure around it. This is why the boiling point of a liquid at a higher elevation is lower than that at a lower elevation. At the high elevations, the earth's atmosphere doesn't exert as great a force on the liquid so the liquid's vapor pressure equals that of the atmosphere at a lower temperature.

You also have to keep in mind how the measurements of atomic radii are done. With most elements, it is done in the form of some type of bonding so there is a bit of a "falsity" there. Noble gases don't even form bonds with themselves like the halogens and other covalently bonded gases do, so the radii you read in regards to noble gases are a bit misleading. You can compare a noble gas radius to another noble gas radius and have the measurements mean something, but if you compare a noble gas radius with that of any other element in its period it's a bit misleading. Also, the noble gases do have nuclear attraction. ALL elements have nuclear attraction. That is part of what keeps the electrons in place. Just because an element doesn't form bonds easily, if at all, doesn't mean that they don't experience nuclear attraction.

It was actually dimethyl mercury that the researcher Karen Wetterhahn at Dartmouth had spilled a drop onto her glove. Methyl mercury is still toxic, but the dimethyl variety is a bit worse.

1): Nitric Acid. (Even though it's listed as one of my nastiest chemicals, it's also one of the most useful. In conjunction with HCl you can dissolve nearly any metal there is). 2): Hydrochloric Acid. (A basic, simple acid that can be incredibly useful for the generation of other chemicals). 3): Sulfuric Acid. (An incredibly strong acid, yet one that doesn't interfere with other reactions all too much). 4): Cesium. (I've loved it ever since I heard about it after the alkali metal demonstrations in high-school chemistry. Granted, the metal isn't nearly as "KABOOM" as one would think once you've actually seen it react with water, but the incredible color and liquidity of it is amazing. Thank god for ampoules). 5): Sodium. (The best representative of the alkalis. Much stronger than lithium, yet much safer than potassium. In addition, it's dirt cheap so you can get a good lot of it for almost nothing. A nice sized chunk will give you the best "boom" with a nice long delay to it, yet the metal won't become a severe fire/explosion hazard on its own like potassium will). 6): Hypochlorites. (Great for the generation of chlorine gas). 7): Chlorine Gas. (Great for the generation of elemental halogens as well as interesting inter-halogen compounds). 8): Iodine. (Only because nitrogen triiodide is what got me started with my element collection). 9): Nitrates. (So many great reactions involve nitrates and their versatility is great). 10): Ethanol. (A great solvent, a good reactant when needed, and a great way to relax after a long day at work. )

Damn. It's a shame you aren't selling individual samples because I've been DYING to get a sample of ampouled potassium that is free of oxide. My lump is nice and hefty, but it is heavily peroxidized, superoxidized and ozonized and doesn't match nicely with my ampouled samples of lithium, sodium, rubidium, and cesium. The only place I've seen that sells ampouled potassium is http://www.smart-elements.com and I'm not paying his insanely high prices.

1): Hydrofluoric Acid 2): Concentrated Nitric Acid 3): Nitroglycerine (Think MASSIVE headache and then nearly non-existant blood pressure). 4): Dimethylmercury 5): Cesium 6): Cesium hydroxide 7): Liquid Fluorine 8): White Phosphorus 9): Any soluble radium compound 10): Butyl Lithium

I HIGHLY doubt that. Unless your professor took the liquid N2 and sprayed it into a mist in the air, the "smoke" was not liquid nitrogen. The "smoke" you saw was suspended particles of solid H2O in the air. Liquid Nitrogen is so cold that the little bit of humidity which is in the air will solidify into small ice particles. The exact same effect is seen when you put solid CO2 (dry ice) into water.

You'll start coughing and choking and gasping for air almost immediately. You'll also feel an intense burning sensation in your lungs that won't really go away. Your diaphragm muscle will feel a bit sore from all the VERY hard coughing. The thing is, that's not when the problems will start. A few hours later, you'll find yourself short of breath as the cells in the alveolar sacs in your lungs have been exuding liquid thanks to the damage caused by the chlorine gas. This is known as pulmonary edema and it's where you basically drown in the fluid that is leaking from the cells in your lungs. You may feel fine, but as time goes by the fluid builds up until you just can't breathe any more. That is why chlorine, bromine, and a lot of mustard and war gases are NASTY substances that you absolutely MUST avoid breathing.

Well with poppy seeds there is a definitive ratio of codeine, morphine and narcotine which will help differentiate between poppy seed consumption and opiate use in a drug test. (Yes the initial, cheap screening of a blood/urine sample will test positive but the more refined GC/MS confirmation will show the ratio to be that of poppy seed ingestiong). Anyway, in the United Kingdom Heroin (diamorphine) is a prescription drug. However it is typically only prescribed for terminally ill cancer patients. Monoacetylmorphine is only a breakdown product of heroin, or the main side product when one attempts to generate heroin without the use of acetic anhydride. I am not willing to provide a definitive statement on any of this, but it doesn't looked good for your friend. Narcotine and morphine and natural components of raw opium, and monoacetylmorphine is ONLY present from a homemade attempt at heroin production, or as a breakdown product of heroin. At elevated temperatures, such as those that would be found if one was attempting to "cook" a batch, heroin itself will break down into monoacetylmorphine. The heat of a burning cigarette is hot enough to begin the decomposition. The presence of the three compounds mentioned in your original post all combine to paint a not so good picture. While your friend may not have been involved in any heroin production, it sounds like someone he has contact with was.

Technically speaking, AC electrolysis really doesn't work. The point of electrolysis is to separate a chemical through the use of electricity and isolate it's components. With AC, since the anode and cathode are constantly switching back and forth, you really aren't separating the components. You're just decomposing the compound and creating a mixture of products. In terms of usefulness, AC Electrolysis is completely useless.

Well the Ca(OCl)2 I used passed the vinegar test. I dropped some in some vinegar and some in some lemon juice to see if any CO2 bubbled off. There was absolutely no bubbling from the solution. The 99% purity listed on the ingredients list was most likely correct. Any CO2 that could have formed would have dissolved along with the HCl during the initial water passing. We actually lost quite a bit of Cl2 into the water during the reaction, but there was enough Cl2 in the test tube to see provided you had a white background, or you looked down the long end of the tube.

I remember when I bought my red phosphorus for my element collection right at the tail end of it being available on E-Bay. I got a LOT of the stuff. Enough to fill up a 20 mL vial nearly 80% of the way. That vial hasn't been opened since the P was put in and the vial capped off, but the phosphorus still had a very distinct odor to it that I'll probably not forget.

In low concentrations, Cl2 is an INCREDIBLY pale green color that you can almost not see. You should put a white piece of paper behind the tube, or look through the tube from the top end to see if you can notice the green color. When you see samples of chlorine that have an intense green-yellow color to them, it's usually a fairly substantial amount in a container. I fell under the same impression that chlorine always had a deep coloration to it until I made my first batch and saw that it really didn't. BTW, I made my chlorine by taking a calcium hypochlorite "paste" made with dry Ca(OCl)2 and water, then added concentrated HCl to it. The gas was bubbled through water to remove any excess HCl, then passed through some anhydrous NaHCO3 to remove any further moisture. The dry Cl2 was then sealed in a glass ampoule.

NO2 + H2O will not give you nitric acid. It will give you mostly nitrous acid with perhaps a teency, tiny bit of nitric acid. Just look at the balanced equation and you'll see your problem.

I've actually NEVER heard of potassium nitrATE being used as a preservative or curing agent. Potassium nitrITE, yes, but not nitrate.

Every chemical we work with has the potential to be toxic for us. Hell, a recent radio station contest that went wrong proved that plain old H2O can be toxic to us. A simple use of good chemical hygene, common sense, and paying attention will keep you good and safe for a long, long time. This is MnO2 we're talking about, not KCN, Ni(CO)4, AsH3, etc.

A fingernail's size pile of aluminum powder to one small crystal of iodine and one drop of water. The reaction is near instantaneous.

Exactly.

In regards to real measurements and significant figures, you're bound by just how precise your measuring instrument is. If you have a ruler that has centimeters and millimeters on it, you're limited to one place after the decimal point and no more since your instrument isn't that precise. (You can have up to 3 significant figures if your measurement is something like 12.8 cm or 128 mm). You can't "create" more significant figures. If you have an imprecise measurement tool, then your figures and calculations are forced to be just as imprecise.

Nope. Think again. What exactly is density? It is a measurement of Mass divided by volume. A bond can't have density since a bond isn't really a mass. That's like trying to calculate the density of the word "bug". It's just not logically possible. So back to your question. The density of a substance is the measurement of how much mass exists in a fixed volume. Your comment on vibration does begin to lead you down the right path. What is the difference between the intermolecular/interatomic interactions in a liquid and in a solid? If you can answer this question, as well as draw out a few water molecules, the answer should be pretty evident.

Take a look at the structure of water. The H-O-H bond angle shows you everything you need to know. Remember, when water is in a solid state the H is attracted to the O of another water molecule. If you draw it out, the answer will appear for you immediately.

You could also add a tiny, and I mean TINY, bit of iodine crystals to the powder and add a tiny drop of water. If aluminum, it will violently react. If another powdered metal, there would be little reaction if any.

Well, if you want to look at it kind of optomistically the people like that do tend to reduce in number on a daily basis.

No they're not. Only the initial x86 processors and pre-pentium level processors are pure gold pins and those microchips have already been reclamated. If you read the post I made in here earlier, you'd have read that once manufacturers realized they could get away with a thin gold plating they started doing that on all their microprocessors. What was once a scant bit of gold then turned into a microscopic bit of gold.

And you also need to do your own homework. We are here to help, not do your work for you. When you post a question without showing ANY work at all, then soon thereafter demand that someone give you your answer you look like nothing but an individual unwilling to do his/her own work. If my assumption is incorrect, then my apologies but you really need to alter how you present yourself here. If my assumption is correct, then good riddance as I doubt you'll be back here unless you want someone else doing more of your own work for you.