1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Calculating First Ionization Energy

  1. Oct 23, 2009 #1
    1. The problem statement, all variables and given/known data
    I have an exam on Monday and do not know how to do this example problem.

    Use the following information to calculate the first ionization energy of Li.
    LiF(s) → Li+(g) + F −(g) 1050 kJ/mol LiF
    Li(s) + ½ F2(g) → LiF(s) −617 kJ/mol Li
    F2(g) → 2 F(g) 160 kJ/mol F2
    Li(s) → Li(g) 161 kJ/mol Li
    F(g) → F −(g) −328 kJ/mol F

    (a) 520 kJ/mol Li
    (b) 440 kJ/mol Li
    (c) 426 kJ/mol Li
    (d) 346 kJ/mol Li
    (e) 216 kJ/mol Li

    The answer is a but I cant figure out how to get it. If you could show me the process I would greatly appreciate it.

    2. Relevant equations
    H=Bonds Broken - Bonds Formed

    3. The attempt at a solution
    617 = 160 + 161 +1050 + x - 328
    x = 426
    I know this method isn't right because 1. It makes no sense 2. It doesn't follow the bond enthalpy formula
    1. The problem statement, all variables and given/known data



    2. Relevant equations



    3. The attempt at a solution
     
  2. jcsd
  3. Oct 24, 2009 #2
    How can you combine the reactions given to have a balanced equation with Li(g) as a reactant and Li+(g) as a product, and all the others as spectators?
     
  4. Oct 24, 2009 #3

    Borek

    User Avatar

    Staff: Mentor

    Don't go for bonds, use Hess law (which is basically what PhaseShifter suggests).

    --
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook




Similar Discussions: Calculating First Ionization Energy
  1. Ionization energy ? (Replies: 3)

  2. Ionization Energies (Replies: 5)

Loading...