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ProjectTae
ProjectTae Posts: 461 Member
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Anyone really good at chemistry? So I'm usually a pretty good test taker, however this year AP chemistry is kicking my butt! Our teacher shocked us all today by offering a take home extra credit question on our test today! We're doing equilibrium problems and I'm stuck. I'm guessing it's an 'ICE' problem?? Can anyone help?

At a certain Temp, a 1.00-Liter flask initially contained 0.298 mol PCl3(g) and 0.00870 mol PCl5(g). After the system had reached equilibrium, 0.00200 mol Cl2(g) was found in the flask. Gaseous PCl5 decomposes according to the reaction: PCl5(g) = PCl3(g) + Cl2(g). Calculate the equilibrium concentrations of all species and the value of Kc.

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  • Jyster
    Jyster Posts: 74 Member
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    How much extra credit do I get if I solve this for you? Would you actually learn if one of us gives you the answer? I work as a tutor on a college campus and feel the best way for you to learn is to work the problem out in small steps and show your work. that way if someone chose to help you they could point out your mistake or follow your train of thought.

    Sorry to be the stick in the mud but I make my students work it out, maybe I'm evil because I never had the option of a tutor when I was messing up in school and we didn't have the internet back then :)

    <<< obviously I do not tutor English and Grammar. Wow I have to work on that.
  • ksmith2187
    ksmith2187 Posts: 53
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    lol.. do lecturers ever come up with their own problems?..

    google : Topics 7 & 17: Equilibrium (SL/HL)

    the working out and answer is example 1 on the bottom of page 8 - i have had this question before in my introductory chem class in uni.

    make sure you understand how you get to the answer.

    have fun - i hate chem
  • ProjectTae
    ProjectTae Posts: 461 Member
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    How much extra credit do I get if I solve this for you? Would you actually learn if one of us gives you the answer? I work as a tutor on a college campus and feel the best way for you to learn is to work the problem out in small steps and show your work. that way if someone chose to help you they could point out your mistake or follow your train of thought.

    Sorry to be the stick in the mud but I make my students work it out, maybe I'm evil because I never had the option of a tutor when I was messing up in school and we didn't have the internet back then :)

    <<< obviously I do not tutor English and Grammar. Wow I have to work on that.
    Ok so lets start!

    Ummm.....

    Kc=[PCl3] [Cl2] / [ PCl5]

    Initial conc. [.00870] (PCl5) [.298](PCl3) ??(Cl2)

    Change -x +x +x

    Equlibrium (.00870-x) (.298 +x) [.00200]

    Now I don't know what to do :(
  • ProjectTae
    ProjectTae Posts: 461 Member
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    lol.. do lecturers ever come up with their own problems?..

    google : Topics 7 & 17: Equilibrium (SL/HL)

    the working out and answer is example 1 on the bottom of page 8 - i have had this question before in my introductory chem class in uni.

    make sure you understand how you get to the answer.

    have fun - i hate chem

    Thankyou! Ok question time!!!
    why is Cl 0?? for initial concentration, because it was formed as a product? and why is the value at equilibrium the change?

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