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Homework Help: Chemistry-equilibrium reaction question

  1. Mar 31, 2010 #1
    1. The problem statement, all variables and given/known data

    In lab, we mixed 3mL of 0.10 M acetic acid.

    I was given that the principal equilibrium is:
    HOAC + H20 <----> H30+ + OAc-

    We then added 1.0 M sodium acetate and a drop of methyl orange indicator. The color changed from redish to yellow.

    I figured out (correctly) that the principal equilibrium shifts to the left because of the increase in OAc- ions.

    The question is: What other solution could you have added to the acetic acid solution instead of one with acetate ion to cause the principal equilibrium in the acetic acid solution to shift in the same direction? Would this cause the same color change???

    2. Relevant equations

    3. The attempt at a solution

    I THINK (though I'm honestly not very good with chemistry), that if I add a strong acid it will also shift to the left? For example, maybe HCl or HBr or something. I think this because the strong acid would increase the H3O+ ions, also shifting it to the left.

    And I don't see why the color wouldn't change the same?

    I have no way of checking if I'm correct which is why I'm asking. Any comments would be great! thank you
  2. jcsd
  3. Apr 1, 2010 #2


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    Staff: Mentor

    Your thinking seems correct to me :smile:

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