Help with some general chem questions

Discussion in 'Postbaccalaureate Programs' started by kimt2234, Nov 28, 2005.

  1. kimt2234

    kimt2234 Member
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    Hello,

    I have an exam coming up and for the life of me, I cannot figure out a few questions that are likely to appear. Anyone can help, I am desperate.

    Question 1

    In molecular orbital models, does F3 (3 is a subscript) exist?

    Question 2

    When drawing the lewis dot structure for XECL4- I calculate 37 electrons. DOes this mean it can't be drawn since it is an odd number, or is there a way to draw it?

    Question 3

    I am trying to find the molecular weight of a diatomic molecule and I am given density in g/mole at STP. What equation and conversions would I use to solve this problem? I convert g/mole to g/liter and use the formula mm=dRT/P but I am not getting even close to the answer the book has.

    QUestion 4
    How many sigma and pi bonds does F3CCH(N3)CN have?

    Question 5

    What is the unit of gas constant R in MKS system?

    Thank you so much for your help. Normally I would not ask, but I have been working on probs since last wednesday and am going made with these!
     
  2. carn311

    carn311 Dead tired.
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    Question 1

    In molecular orbital models, does F3 (3 is a subscript) exist?
    Look in the quantum physics chapter of your text book. There should be a diagram showing what order to add electrons into the orbitals. I only have my Organic text with me now.


    Question 2

    When drawing the lewis dot structure for XECL4- I calculate 37 electrons. DOes this mean it can't be drawn since it is an odd number, or is there a way to draw it?
    This molecule is an anion (has a net negative charge). When atoms have negative charges we add up all of the electrons (37) and THEN add an additional electron for each net negative charge and subtract an electron for each net positive charge on the molecule.



    Question 3

    I am trying to find the molecular weight of a diatomic molecule and I am given density in g/mole at STP. What equation and conversions would I use to solve this problem? I convert g/mole to g/liter and use the formula mm=dRT/P but I am not getting even close to the answer the book has.

    QUestion 4
    How many sigma and pi bonds does F3CCH(N3)CN have?

    Draw the lewis structure...I'm sorry to day if you cant do this by now then you're in trouble. Now, each single line is a sigma bond and each double line is made up of one sigma AND one pi bond.


    Question 5

    What is the unit of gas constant R in MKS system?

    Do you own a text book? And Im not being sarcastic. Look this up...

    Thank you so much for your help. Normally I would not ask, but I have been working on probs since last wednesday and am going made with these!
     

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