UPSB v4

Spammer's Bin / CHEMISTRY - STOICHIOMETRY

  1. Clyde
    Date: Mon, Dec 13 2010 09:49:17

    is anyone pro at this? fuck i dont understand any single shit and i copied all my HW's from my classmates and im lucky that most of our quizzes are on computer and i get to cheat...this is the 1st time i got this stupid in science = = stoichiometry is so confusing...i dont get how my classmates get the answers -.- anyone else having problems w/ stoichiometry? getting theoretical, actual & percent yield, etc.

  2. AoD1
    Date: Mon, Dec 13 2010 10:12:00

    um no one gives a flying fuck.... why ask advice on a "penspinning" board?

  3. Clyde
    Date: Mon, Dec 13 2010 12:04:04

    idk

  4. AoD1
    Date: Mon, Dec 13 2010 12:05:10

    ..... upsb is full of idiots.... think about it......

  5. shoeman6
    Date: Mon, Dec 13 2010 12:50:04

    Idk, I always come to UPSB for help. Anyways, stoichiometry is just following your units, always bring things to moles because that's what links your reactants and reagents together, remember to write out your units and use those relationships to solve for whatever it might be moles grams, atoms etc. It really isn't that difficult, think of a mol like a dozen, and then you have all your conversion factors right there on the periodic table and in your balanced reaction.

  6. tylt
    Date: Mon, Dec 13 2010 13:13:06

    Just make sure that everything cancels out top to bottom and always remember your unit conversions. Its more of a puzzle then anything, just cancel things out until you get to what you want at the end for your units. And always remember your significant figures because teachers will nail you for sig-fig errors.

  7. Rarity
    Date: Tue, Dec 14 2010 09:48:27

    @AoD1 After seeing the above, clyde won't think about it. :D

  8. Awesome
    Date: Wed, Dec 15 2010 23:15:21

    all your chemical formulas will be in moles so 2H2+O2 -> H2O means 2 moles of hydrogen and one mole of oxygen forms 2 moles of H2O. A mole is approximately 6.02 * 10^23. Now this is fine and all, but how the hell are we supposed to count out something small like atoms right? We just weigh them, so you need your periodic table, each element will have an atomic weight, O is 16.00, that means 16 grams of oxygen will be one mole of oxygen. for compounds the molecular weight is the sum of all the atomic weights, so for H2O we have 2 Hs which weigh 1.01 a piece, and 1O which is 16.00 ( a LOT of work went into figuring this stuff out, be grateful its made so easy for you) 16.00+1.01+1.01=18.0 so for every 18 grams of water is one mole, to get this we need one mole of oxygen or 16 grams of oxygen and 2 grams of hydrogen, this is from the balanced chemical formula. For most practical purposes we do this all by weighing the substances so you need to convert moles to weight and weight to moles all the time. Think of stoichiometry as a computer of sorts, it only works with the input as moles, but to humans weights are whats useful. weight -> moles -(input)> figure out the ratios of whatever your interested in -(output) >moles -> weight make sure you can balance equations, come up with molecular weights and take your time on the problems and it should be easy. Or you can just do tylts way with a bunch of practice problems with solutions until whatever you do gets you the right answer most of the time.

  9. Clyde
    Date: Fri, Dec 17 2010 11:21:57

    thx but its xmas break already and idc about it anymore hahhaa the chem exam was easy lol the matching type was 15 pts. and the answers were arranged in alphabetical order lol A-O..even the multiple choice was easy haha what I just remembered is: given mass of element ( 1mole/ atomic mass of given element)( mole of reactant/mole of given element)(atomic mass of reactant or 6.022x10^23 or 22.4L / 1 mole)