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Homework Help: Ionizing a covalently-bonded molecule?

  1. Aug 25, 2012 #1
    1. The problem statement, all variables and given/known data
    What happens to a water molecule if it is hit by a high energy electron or photon?

    2. Relevant equations

    3. The attempt at a solution

    My knowledge of chemistry is very limited, and my guess is that it would be ionized:

    e + H_2 O \rightarrow H^+ + OH + 2e

    Here, a high energy electron hits the molecule and releases 1 electron from the H atom, making it a cation. Two electrons appear in the products: 1 from the H along with the original electron.

    If something like this were possible, then could a "hydroxide cation" be formed?

    e + H_2 O \rightarrow H + OH^+ + 2e

    And if a photon strikes the molecule, how about

    \gamma + H_2 O \rightarrow H_2 + O

    (Can water absorb photons?)

    I am trying to understand how a covalently-bonded molecule "breaks up" when bombarded with cosmic rays, and would like to know if any of these examples (which contain such a molecule) are plausible. Thanks for your help!
  2. jcsd
  3. Aug 25, 2012 #2


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    Gold Member

    You are reducing water, so the reaction is simply [tex]H_2O+e^- \rightarrow \frac{1}{2}H_2+OH^-[/tex]
    You just can't go and cleave bonds that easily. And for the cosmic rays, I think that everybody can form radical, as many species does in UV light. (Cosmic rays are too powerful I suppose)
  4. Aug 26, 2012 #3


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    Also known as ionizing radiation. There is a lot of information on the web regarding ionizing radiation and it's effects on the water molecule.
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