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How does a catalyst affect equilibrium?

  1. Feb 26, 2015 #1
    OK I clicked a bunch of similar discussions, but it still makes no sense, I barely know what a catalyst is, besides the fact that they do affect the rate of reaction but not the equilibrium expression or pressure, which just got me hella fudged up. And i don't want any over complicated explanations lmoa, but any help would be greatly appreciated.

    ---Also, when writing a reaction, I get really confused on how the products are set up, after that I can't easily calculate PH and such, and I do know it involves how strong or weak the acids and bases are, and if it lends protons or not, but I don't really understand how any of this works together to tell you how the products are set up
    Ex; HOCl + H20 <--> H30+ + OCL- obviously this is correct but I don't understand how they got H30, and not OH, and H2OCL, any descriptions on this would help. I hope im not restricting any guidelines cause this isnt really a problem in my hw, its just helpful in many parts to it.

    Sorry if my questions sound stupid, I honestly don't know sometimes how I manage AP Chemistry, But im always looking for more ways to succeed!!!
     
  2. jcsd
  3. Feb 26, 2015 #2

    Borek

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    Staff: Mentor

    So, what your question is? Especially as you already know the answer to the one posted in the thread subject is "it doesn't"?

    As to the latter question - do you ask about "how did they originally found out these things" or "how you predict what to expect"?
     
  4. Mar 2, 2015 #3
    Catalyst speeds up a reaction. If it is an equilibrium, it speeds up both the forward and backward reactions by same factor. The molecules will be converting back and forth faster but their total numbers will remain same at any time.

    Acidity is based on how acids dissociate. In this case, the O-H bond is weaker than O-CL and so, the O-H bond is broken easily. This is common with most oxoacids with electronegative atoms, including sulfuric acid, nitric acid, perchloric acid and even carboxylic acids. Only when metal is involved, the M-O bond breaks (or it may take a proton from water). So, in a H-O-X system, the electronegativity of the atom X decides which bond will break.
     
  5. Mar 2, 2015 #4

    Borek

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    Explain that to permanganic acid (and many others).
     
  6. Mar 2, 2015 #5
    Sorry Borek, I missed those! Apparently it looks like high oxidation state metal is similar to highly electronegative atom. I admit, I did not research a lot on this, simply realized this connection after your question.
    This even seems to apply to electronegative atoms! Perchloric acid is stronger than hydrochloric acid...
     
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