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General Chemistry-HELP

  1. Aug 7, 2011 #1
    1. The problem statement, all variables and given/known data

    Calculate the equilibrium constant if you are given gibbs energy for the following molecules
    NH3=-26kJ/mol
    H2O-237.13kJ/mol
    NH4+=-79.31kJ/mol
    OH-=157.3kJ/mol

    How many moles of NH4Cl must be added to 1.0L of 0.10M NH3 to make a buffer whose pH is 9.0?



    2. Relevant equations
    Henderson hasselbach equation,
    delta G=RTlnK



    3. The attempt at a solution
    1) How do you calculate equilibrium constant if you don’t have the temperature to use G=RTlnK
    2) For the second half the question, I am thinking of using Henderson hasselbach equation to determine the concentration of NH4Cl. If not, how should I go about solving this question.
     
  2. jcsd
  3. Aug 7, 2011 #2
    Just need some help starting out with the problem
     
  4. Aug 9, 2011 #3
    I believe unless otherwise stated, you assume T=298.15K (standard conditions).

    I'm not familiar enough with buffer solutions to help with the rest, sorry!
     
  5. Aug 16, 2011 #4

    Borek

    User Avatar

    Staff: Mentor

    Once you have K, Henderson-Hasselbalch is the way to go.
     
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