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Homework Help: Calculate the molar enthalpies of reaction occuring in parts A and B

  1. Dec 24, 2011 #1
    1. The problem statement, all variables and given/known data
    Part A:
    Mass of Mg (s) = 0.31 g
    Initial temperature of calorimeter contents = 24.1 C
    Finial temperature of calorimeter contents = 36.8 C

    Part B:
    Mass of MgO (S) = 1.22 g
    Initial temperature of calorimeter contents = 24.0 C
    Finial temperature of calorimeter contents = 31. 9 C

    100.0 ML of HCL used and -601.6 KJ/mol Mg reacted

    2. Relevant equations
    Calculate the molar enthalpies of reaction occurring Parts A and B.


    3. The attempt at a solution
    Part A (answer):
    Enthalpy change of reaction = (chemical amount)(molar enthalpy of reaction)
    =Enthalpy change or reaction= (0.31g)(1mol/24.31)(-601.1 kJ/mol/1mol)
    = -7.665 kJ
    = -8 kJ

    Part B (answer):
    Enthalpy change of reaction = (chemical amount)(molar enthalpy of reaction)
    =Enthalpy change of reaction= (1.22g)(1mol/40.31g)(-601.1 kJ/mol/1mol)
    = -18.19 kJ
    = -18 kJ
    1. The problem statement, all variables and given/known data



    2. Relevant equations



    3. The attempt at a solution
     
    Last edited: Dec 24, 2011
  2. jcsd
  3. Dec 24, 2011 #2

    Borek

    User Avatar

    Staff: Mentor

    Shouldn't you use q=mcΔT?
     
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