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AAMC 5 Question

Discussion in 'MCAT Discussions' started by 5moreminutes, Apr 21, 2007.

  1. 5moreminutes

    5moreminutes Junior Member 2+ Year Member

    Jul 17, 2006
    QUestion # 14 Physical Sciences

    nCDP <-> CPn + nHPO42-

    according to this equation, the concentration of the polymer with respect to (HPO4)2- is ?

    And the answer is 1/n [HPO4]2-..
    I just dont get it even after reading the explanation.
    anyone have any insight on this one ?

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  3. GTsquirrel

    GTsquirrel 2+ Year Member

    Apr 10, 2007
    nCDP <-> CPn + nHPO42-

    Okay, so you have to first understand the equation. The equations says that n molecules of the compound CDP (a diphosphate) (left side) will form one long polymer (with a total of n monomers) of CP (a monophosphate). So imagine n molecules of CP strung together like a pearl necklace, but keep in mind that this is still ONE molecule. The last part says that for every n molecule of CDP you use in the reaction, you will produce n molecules of HPO42-. So, let's say you use 10 molecules of CDP in the reaction. You will produce 10 molecules of HPO42- but only ONE molecule of CPn that consists of 10 monomers. You will always get one CPn for each reaction, but you will get n molecules of HPO42-. So, to determine how many molecules you get of CPn (which is always 1), you take the number of HPO42- molecules (which will always be n times greater than CPn) and divide it by n because n/n is 1.

    Hope this helps.
    RiPSTONE likes this.
  4. 5moreminutes

    5moreminutes Junior Member 2+ Year Member

    Jul 17, 2006
    thanks,that does make sense, but its more of a math problem then physics , i guess
  5. evoviiigsr

    evoviiigsr 7+ Year Member

    Dec 22, 2006
    its chemistry not physics

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