Applied Chemistry

Sorry long question but this has been bothering me for a while.. How is it that in some reactions light can provide the activation energy requred to break the neccesary bonds when in terms of temperature the energy is ridcoulously high. e.g. chlorination of methane Cl2 ==> Cl + Cl CH4 + 2Cl => CH3 + HCl etc etc In this reaction light is enough split the chlorine into free radicals while in its absence the heat required is over 400C. I would imagine only 1 mole of photons would be required to break 1 mole of CL2 molecules so you could calculate the activation energy using E=hf right. I can't be bothered to do the calculations but becasue of planks…

Hello, This may seem like a bit of a silly question but out of interest is there anyway of keeping a liquid that is already very cold eg. liquid nitrogen and keeping it cold using electricity ! i know it seems silly but any ideas Thank you

I write for my high school's newspaper and would like to run a story on the nutrition of our school lunches. From what I've looked up, the food would have to be dried and burned in a bomb calorimeter. At school we use calorimeters with water in them. It seems that bomb calorimeters are far too complicated. Is there any simple way to find the Calorie content of the school food without very expensive equipment or is this experiment not feasible?

I recently did a backwards titration... Instead of adding base to acid and indicator, I added acid to base and indicator. The unusual thing was that more of the acid was used than base. Eg. The same titration was carried out normally, add base to acid-indicator, and I get oh 25 cm cube of base used to change indicator color. Now I reverse things around and add acid to base-indicator and get 45 cm cube of acid used! I was assuming on the same volume readings either way:confused:

I recently acquired a whole lot of chemistry equipment (dozens of test tubes, beakers, flasks, etc...) and have since been messing around a little in my basement. I've become interested in acidic reactions, specifically the reactions between HCl (which I get from muriatic acid) and various metals (zinc, aluminum, iron, lead, etc). Theoretically, the products of these reactions should only be hydrogen gas and a metal chloride, but there is always a very strong odor emanating from both the acid, the reaction, and oftentimes the products. So my question is this: are there any safety hazards in these reactions, perhaps involving dangerous gases? Muriatic acid is abo…

Electronegativity - How is it measured? I recently found myself asking how electronegativity is measured and frankly my standard chemistry textbook provides nothing of use on the topic. What is it measured against and how it is measured? Is it measured against Fluorine that is the most electronegative and also who standardised the system for measuring eectronegativity? Any help apprectiated! Cheers, Ryan Jones

If you had 3 different gases in a container and all three had a different number of moles of gas. Could you calculate there volume seperately? (using avagadro's V=an )? Even though there are multiple gases, the particles are assumed to not take up space, so you can calculate their volume, and then their molarity, right?

Determine the number of atoms in 2.25 moles of nitrogen gas. I'm confused >.< Do I: 1) multiply 2.25 mol by 6.02 x 10^23 atoms or or 2) multiply 2.25 mol x 6.02 x 10^23 molcules x 2 atoms. or is it something else? Also, how do I do this problem? Calculate the mass of 3.01 x 10^23 formula units (ions) of Strontium hydroxide. Please help if you can. ~____~

My Automotive technology class is building a mini wind tunnel. The project is complete but we can't figure out a substance that gives off the vapor trail but still is eviormentaly safe and does not conflict to fire marshall's or smoke ditectors or sprinklers. If anyone has any ideas it would be greatly appriciated

I'm looking at the low resolution NMR spectrum print out for paracetemol and I'm a little confused. (You can see paracetemol structure here) http://www.ch.ic.ac.uk/rzepa/mim/dru...racet_text.htm The first and highest peak has a chemical shift value of 2 and is labelled 3H which I can identify as the hydrogen on the hydroxy group due to oxygens electronegative behavior. However there are 4 more peaks with two at 6.5 and 7.5 labelled '2H' (equal height) and the final two at 9 (high peak) and 9.6 (lower peak). Does this indicate that the final four hydrogens are all in different enviroments or only in two. I would have thought there would be only two more peaks with…

Hi there everyone! Can anyone reccomend any good chemistry books? Thanks to woelen, I have bought the ones he suggested and have found them helpful - just wondering if there are any more I should look into Cheers, Ryan Jones

Anyone know of a chemical that burns at such a low temperature as to not burn you so you could quite literally set yourself alight. Don't worry i'm not planning anything of the sort but I just heard some talking about something similar. Anyone know what it is if it actually exists?

I have to identify an unknown liquid. Smells a bit like tiger balm. Refractive Index of 1.5167 @ 22.5 degrees C. Infrared Spec: I have the big broad obvious OH stretch. Two strong peaks around 700 & 750 which is characteristic of a mono subst' benzene ring (NMR shows a big ass (5x) peak at 7.2). C-H stretching. And what I think is a C-O stretch of a primary alcohol. UV-Vis: Lambda max @ 260 nm. Problem is that I'm no NMR expert. Its up to me to learn. I need a good tutorial web site. If anyone can help me out on the basics of chemical shift, etc would be appreciated. I want to figure it out on my own, only way I'm going to learn, but I can provide scans …

Does anyone know where can I buy Zinc Sulphide and Titanium Dioxide in very small particles? Regards, Dan

Not sure if this would go under chem or mat, but here it goes... What is the scale that you use to convert mR/hr to CPM in radioactivity?

I would like to use Thermopiles to store energy in a cell then run an ultra low wattage bulb from the cell. I would like to supply the thermopiles using the energy from - I2R Heat Losses I have been trying to come up with a way of using the i2r heat losses found in many machinery control centres at industrial installations. The areas around the busbars which supply the energy are hot sometimes very hot and heat the air in the room to above 30 degrees. I don't know if you were to clip something onto the busbars whether or not it would be detrimental for the supply of energy yet but I will investigate. Maybe the heat could be absorbed from the area aroun…

I have sme glass ware that scrubbning and soap wont clean off. Theyre stained by stuff such as metal salts and stuff. What chemical mixture/solution will clean them up? Perfereably ones that do the cleaning without scrubbing.

Please help with this problem, I really think my method is right, but the book has different ideas. "The density of liquid nitrogen is 0.808 g/ml at -196 C. What volume of nitrogen gas at STP must be liquified to make 10.0 L of liquid nitrogen?" so [math] \ce{N2(g) -> N2(l)} [/math] The first step is to find the number of moles of N2, so g = D*V so g = [imath] .808 $g/ml$ * 10.0L[/imath] = 8.08 g moles = [imath] 8.08 g * \frac{1{mole}}{28.02g} [/imath] = .2883 moles V = nRT/P = [math] \frac{.2883 moles* .08206L atm/Kmol * 298K}{1atm} [/math] = 7.05 L the books answer is 6.46 * 10^3 L What did I do wrong?

How can I get a University to fund me? I need enough money to make two fuel cells (See "Build Your Own Fuel Cell" by Phillip Hurley).

Hi everyone. Does anyone have a good CAS number lookup website? Also, does anyone have a website that tells you what chemicals can be bought legally in each country, I live in the UK incase anyone has anyhting specific. Thanks for your hep and time Ryan Jones

Does any one know anything about Early Alchemy or maybe can help me about this or maybe have some web pages about this I would really apreciated IF ANYONE has some imformation about this please

Hi there everyone! Would anyone like to reccomend some experiements that an amature try? Forget about the Buying Chemicals Online. I've decided that is probably not best to ask this in public view as it could cause problems if people find out where to get the stuff and then blow them selves up and ruin it for other people, its the last thing I want. If a moderator can change the thread title to something aloong the lines of Reccomended Experiments for an Amature I'd be most greatful Cheers, Ryan Jones

Hi everyone, Are there any good chemistrt websites out there? Things like learning the principals, examples, chemical lookups etc? If anyone has any good links the please post them, may help a lot of people! Cheers, Ryan Jones

I'm studying for this chem. quiz, and I'm having trouble with this concept the proffesor barely covered, yet is going to be on the quiz anyway. Calculate the pH of the following solutions. a.) 0.10 M CH3NH3Cl b) 0.050 M NaCN There are other examples, but I can't figure out how to calculate the Ka of the solutions.

Okay, here are several seemingly very simple questions but I've never found out the answers to: 1. Does hydrogen ever bond ionically with non-metals (you're taught in HS that they do). If they do, how do you tell an ionic hydrogen compound from a covalent hydride? 2. Combustions w/o hydrocarbons. How do you determine them? Are all reactions with a O2 on the left combustions? What about 2H2 + O2 yields 2H2O? 3. How do you determine the charge of a transition metal in the product given only the reactants? So for example: copper + acetic acid would yield ? My teacher taught me in HS that it should be copper acetate, but what's the charge on Cu here? Thx to anyone that …