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Homework Help: 2 quick chem question

  1. Jun 14, 2005 #1
    Why do geometric isomers only exist in the alkene family but not in alkanes?

    What are different ways of increasing the rate of a chemical reaction?
  2. jcsd
  3. Jun 14, 2005 #2


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    the double bond in the alkene alows for roation. Due to the rigidity of the double bond, molecules direclty in contact with the bond have a very hard time moving but the two free bonds on each molecule ( asuming its a two carbon chain) are albe to roate freely.

    This condition is know as Cis and Trans isomerisim.

    Also with more complex alkene there is more double bonds. Also the more complex the alkene, the more side chains it may have. Thus with a large amount of side chains, the chain itself can attach to either the Cis or Trans side of the double bond and thus producing a different molecule.

    The alkanes on the other hand have no double bonds and no matter how you look at them , two molecules with the same chemical formula can not be rearranged differently

    As for increasing the rate of chemical reaction you must:

    • increase surface area
    • increase concentrations
    • increase temperature
    Last edited: Jun 14, 2005
  4. Jun 15, 2005 #3
    thx that clears things up a bit...As for increasing the rate of chemical reaction are there any more ways or just those....
  5. Jun 15, 2005 #4
    i think catalyst will increse the rate of rxn?? pls check
  6. Jun 15, 2005 #5
    neone else?
  7. Jun 15, 2005 #6
    Temperature and in some cases, the concentration of the reactants, depending on the order of the reaction (if you are unsure of what I'm talking about, just ignore it).

    sorry, i didn't read your whole post. And i don't think catalysts speed up the reaction, they simply allow it to occur at a lower energy state by lowering the activation energy.
  8. Jun 15, 2005 #7
    Lowering the activation energy is speeding up the reaction. Think of it in terms of a linear distance. If I am 5 miles from a store one day and 3 miles the next day, when will I get there faster?
  9. Jun 15, 2005 #8
    That's right. It's just all those rules I have crammed into my head tend to get mixed up, especially when its almost 1 in the morning.
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