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? on Chemistry

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If you have a chemical reaction in equilibrium and add more of the product...what happens to the product's concentration, if it doesn't increase? Does it stay the same or decrease a little?

I know the reactants concentration will increase and if it is an endothermic reaction it will absorb energy. But I am confused on the product's concentration

  • ? on Chemistry -

    Lets say you had A concentration, you added enough stuff to alone make a B concentration. The final product will be less than A+B. So, you add, it decreases some of that which was added, but the end is greater than you started with.
    An excellent thing to do is think this out, and figure out why...

  • ? on Chemistry -

    I understand that's what happens....but I thought that it means there is an overall increase in the product since it is higher than what I started with. However my webassign says it doesn't increase in concentration....so then is it considered to decrease? Here is my question:

    N2(g) + 2 O2(g) 2 NO2(g)

    The ΔH° for the reaction above is +66.4 kJ. The system is initially at equilibrium. What happens if NO2 is added to the reaction mixture at constant temperature and volume? (Select all that apply.)

    The reaction absorbs energy.***
    The reaction releases energy.
    [NO2] increases.???
    [NO2] decreases.???
    [NO2] remains constant.???
    [N2] increases.***
    [N2] decreases.
    [N2] remains constant.
    [O2] increases.***
    [O2] decreases.
    [O2] remains constant.

    I starred what I believe to be correct. and ? is on what I'm confused

  • ? on Chemistry -

    Connie, if you will go back and look at your original post, I responded in some detail. Between Bob Pursley's great answer and my detailed explanation, perhaps you can piece it together in your mind.

  • ? on Chemistry -

    Ok I did look back and it makes more sense...but I am confused about this problem. I initially did select that [NO2] increases as well as [N2] and [O2]....I selected that the rxn absorbs energy since it stated that dH= +66.4. I'm not sure which of these is incorrect then??

  • ? on Chemistry -

    For what it's worth, this is what I think.
    But I will rewrite the equation.
    2N2 + O2 + heat ==> 2NO2
    Adding NO2 will force the reaction to the left. I think the intent of the question is to answer that NO2 will decrease because the reaction shifts to the left (but technically the final concn will be larger if NO2 is ADDED).


    The reaction absorbs energy.***No, I don't think so. The reaction is endothermic; therefore, shifting to the left means it is reversed and it will be exothermic.
    The reaction releases energy.I think is correct.
    [NO2] increases.???
    [NO2] decreases.???
    [NO2] remains constant.???
    [N2] increases.***yes
    [N2] decreases.
    [N2] remains constant.
    [O2] increases.***yes
    [O2] decreases.
    [O2] remains constant.

    It may be, if you are keying answers into a data base as a set, that the NO2 question isn't really your problem. It could be that the heat part of the question is what you have wrong and the NO2 actually increases (in which case my remarks about the "intent of the problem" would have been conjecture on my part.

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