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Consider the following equilibrium:
PCl3 (g) + Cl2 (g) yields PCl5 (g)
delta H= -92KJ

The concentration of PCl3 at equilibrium may be increased by:

decreasing the temp (think this is it)
adding Cl2 to the system
the addition of neon
the additio of PCl4

  • Chemistry -

    I don't think so. Remember that Le Chstelier's Principle says that when a system in equilibrium is disturbed it will shift so as to undo what we've done to it.
    When dH is involved I rewrite the equation to make more sense.
    PCl3 + Cl2 ==> PCl5 + heat
    Now, adding PCl3 makes the system want to use up the added PCl3. How can it do that? By reacting more PCl3 with Cl2 to produce PCl6; i.e., shifting the rxn to the right.
    Adding more cl2 will shift to the right.
    Adding PCl5 will shift to the left.
    Adding heat will make it shift to the left.

  • Chemistry -

    Sir, thank you for answering. I thought it was the adding the Cl2, but it was wrong. That is why I went with decreasing the temp, but now knowing that it is wrong as well. I think my only option is the addition of PCl5 (which I meant to put at the top vice Pcl4) I hope I am on the right track.

  • Chemistry -

    Adding heat and adding PCl5 is th only way to shift it to the left (or course decreasing PCl3 and Cl2 will shift it to the left also). Decreasing T shifts the reaction to the right (because if we take temperature away the reaction will shift to the right in order to produce more heat).

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