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Chem help please?

  1. Dec 3, 2004 #1
    Given: Cl2 = 58 kcal/mole ------> 2cl

    1. 58 kcal/mole is the bond dissociation energy T F

    2. 58 kcal/mole is an entropy term T F

    3. this reactin is endothermic T F

    I dont understand get it! Any help woud be appreciated.
     
  2. jcsd
  3. Dec 3, 2004 #2

    Astronuc

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    Staff: Mentor

    Did you mean to write [tex] Cl_2[/tex]+58 kcal/mole [tex]\rightarrow[/tex] 2 Cl?

    If so, then think about what it means. What is happening when [tex]Cl_2 \rightarrow[/tex] 2 Cl?

    What are you doing with the energy?

    Can it be the 'entropy' term?
     
  4. Dec 3, 2004 #3
    Thats one notation. Most textbooks nowadays would say

    [tex]Cl_2 \longrightarrow 2 Cl \ \ \ \ \Delta H^0 = +58 \ \ kcal/mol[/tex]

    to avoid confusion about the "energy" change in the system. (At constant pressure, enthalpy = heat added or lost)

    A positive enthalphy change corresponds with heat being absorbed by the system. A negative enthalpy change corresponds to heat being released by the system.
     
  5. Dec 4, 2004 #4
    Thanks for the explanations :). The formula makes sense now!
     
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