Advertise on Bikeforums.net



User Tag List

Results 1 to 13 of 13
  1. #1
    la vache fantôme phantomcow2's Avatar
    Join Date
    Aug 2004
    Location
    NH
    Posts
    6,266
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)

    What actually Is the MOLE, chemistry

    Okay so today the Mole was introduced in chemistry class...
    6.02x10 (super script) 23.

    I dont know what it was, but that # was about all i got out of the class. Can somebody explain exactly what the Mole does? How does that # tie into the chemical world. Something about finding the # of atoms in a particle?
    C://dos
    C://dos.run
    run.dos.run

  2. #2
    riding once again jschen's Avatar
    Join Date
    Oct 2005
    Location
    San Diego, CA
    My Bikes
    '06 Cervelo R3, '05 Specialized Allez
    Posts
    7,360
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Funny thing is, you really didn't miss much. The mole is simply a conversion factor. 6.02x10^23 of anything is a mole of that thing. If I had 6.02x10^23 dollar bills, I would have a mole of dollar bills. (I would also be filthy rich.) The reason this conversion is useful is because it allows you to convert between your mass measurements on a human scale (grams) and measurements on a molecular scale (much smaller). For example, you can get the mass of a chunk of gold and see that it weighs 197 grams. Since gold has an atomic weight of 197, this means there is one mole of gold atoms in that chunk of gold, or 6.02x10^23 gold atoms.

    Hope that helps.
    If you notice this notice then you will notice that this notice is not worth noticing.

  3. #3
    Mostly Harmless Dead Extra #2's Avatar
    Join Date
    Aug 2005
    Location
    Sittin' on a bench at the railway station, one toke over the line.
    My Bikes
    Giant OCR1, Giant ATX760, Raleigh Retroglide Seven
    Posts
    905
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    From the wikipedia.

    The formal definition of the mole is the amount of substance of a system which contains as many elementary entities as there are atoms in 12 grams of carbon 12, where the carbon 12 atoms are unbound, at rest and in their ground state. [1] The number of atoms in 0.012 kilogram of carbon 12 is known as Avogadro's number. It is approximately 6.0221415×1023

  4. #4
    riding once again jschen's Avatar
    Join Date
    Oct 2005
    Location
    San Diego, CA
    My Bikes
    '06 Cervelo R3, '05 Specialized Allez
    Posts
    7,360
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    By the way, as a point of trivia, the value known as Avogadro's number really is somewhat of a misnomer because it's not unitless. 1 = 6.02x10^23 /mol, or 1 mol = 6.02x10^23

    If the first sentence of this post confuses you, don't worry about it. The more important thing to understand is the two mathematical equations. Basically, when you start needing to calculate things and get units to work out, remember one of those equations. (Either one's fine since they're equivalent equations.)
    If you notice this notice then you will notice that this notice is not worth noticing.

  5. #5
    Meow! my58vw's Avatar
    Join Date
    Sep 2004
    Location
    Riverside, California
    My Bikes
    Trek 2100 Road Bike, Full DA10, Cervelo P2K TT bike, Full DA10, Giant Boulder Steel Commuter
    Posts
    6,025
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    A mole is like a stone is like a slug is like any other of those funny units we have. Everyone else sumed it up real well, 1 mole is 6.626...x10^23 atoms where atoms is a unit of measure.
    Just your average club rider... :)

  6. #6
    la vache fantôme phantomcow2's Avatar
    Join Date
    Aug 2004
    Location
    NH
    Posts
    6,266
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Thankyou very much folks, it makes much more sense now. Not sure how a 2 hour lecture got consolidated into a 6 thread post, but it works
    C://dos
    C://dos.run
    run.dos.run

  7. #7
    '05 NUEser EJ123's Avatar
    Join Date
    Aug 2005
    Posts
    3,374
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    We just did that last week.ug

  8. #8
    .
    Join Date
    Apr 2005
    Location
    .
    My Bikes
    .
    Posts
    3,094
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    It's an Avogadro's Number of something, and there's also molar, how many moles per liter of a solution. The handy thing about the mole is, you use that and the atomic weight to calculate how many grams of This chemical to mix with how many grams of That chemical, to get a reaction that goes without too much of This or That left over.

  9. #9
    DEADBEEF khuon's Avatar
    Join Date
    Aug 2002
    Location
    Catching his breath alongside a road near Seattle, WA USA
    My Bikes
    1999 K2 OzM, 2001 Aegis Aro Svelte
    Posts
    12,155
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Avogadro... mole.

    Avocado... guacamole!
    1999 K2 OzM 2001 Aegis Aro Svelte OCP Club Member
    "Be liberal in what you accept, and conservative in what you send." -- Jon Postel, RFC1122

  10. #10
    Meow! my58vw's Avatar
    Join Date
    Sep 2004
    Location
    Riverside, California
    My Bikes
    Trek 2100 Road Bike, Full DA10, Cervelo P2K TT bike, Full DA10, Giant Boulder Steel Commuter
    Posts
    6,025
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Quote Originally Posted by khuon
    Avogadro... mole.

    Avocado... guacamole!


    I will have to remember that one, my students will get a kick out of it!
    Just your average club rider... :)

  11. #11
    . bbattle's Avatar
    Join Date
    Aug 2005
    Location
    Huntsville, Alabama
    My Bikes
    2014 Trek Domane 5.2, 1985 Pinarello Trevisio, 1991 Colnago Master, '06 Bianchi San Jose, 1987 Moulton Fuso, '80's Gardin Shred?, '82 John Howard(Dave Tesch)
    Posts
    11,696
    Mentioned
    5 Post(s)
    Tagged
    0 Thread(s)
    Molar uses a capital M; a 5M HCl solution has 5 moles of HCl in 1 liter of water. I use moles all the time, every day. But I'm nearly always in the mmole or micromole range. And the poor biochemists across the hall are used to nanomoles.

    You can't say which is more, 5g of hydrogen or 5g of carbon? You've got to convert to moles. Then you can check the mole to mole ratio.

    5g H x 1mole/1g H = 5moles H

    5g C x 1mole/12g C = .417moles C (actually, if we're going to get into that whole significant figures thing, it would be just .4moles C)

    So you got more Hydrogen atoms than Carbon atoms.


  12. #12
    Senior Member
    Join Date
    Dec 2004
    Location
    San Francisco
    Posts
    313
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Somebody help me with this, because i know 22.4L fits in there somewhere. Maybe it's the volume of 1 mole of hydrogen at sea level at room temp? help?
    Say a prayer for all your friends and lovers waiting,
    so sad and patient by your side.

    Say a prayer for all your dreams in need of saving;
    it only takes a day to turn the tide.

    -Grey Revell, Save a Prayercard for the Devilman

  13. #13
    riding once again jschen's Avatar
    Join Date
    Oct 2005
    Location
    San Diego, CA
    My Bikes
    '06 Cervelo R3, '05 Specialized Allez
    Posts
    7,360
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Quote Originally Posted by Ubie
    Somebody help me with this, because i know 22.4L fits in there somewhere. Maybe it's the volume of 1 mole of hydrogen at sea level at room temp? help?
    For an ideal gas, PV = nRT, where
    P = pressure
    V = volume
    n = number of moles
    R = conversion factor
    T = temperature

    At standard temperature and pressure (STP), if you plug in the values for P, n, R, and T, you will find that one mole of gas takes up 22.4 L of volume. Note that the equation does not care what the molecular weight of the gas is, so (assuming ideal behavior) this is true regardless of whether the gas is H2 (MW = 2) or Xe (MW = 131).
    If you notice this notice then you will notice that this notice is not worth noticing.

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •