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Chemistry = looking up numbers then adding/subtracting them

  1. Jan 21, 2013 #1
    1. The problem statement, all variables and given/known data

    Attached

    2. Relevant equations

    Heat of reaction = Heat of formation of all products - heat of formation of all reactants

    3. The attempt at a solution

    1.) It's 0 kJ/mol because it is.

    2.) Every source agrees with 143 kJ/mol or 142.7 kJ/mol (which I've tried).

    3.)

    H = -641.8 - (2(-167.4)-462.0)
    = 155 kJ/mol

    4.)

    H = 2(-397.7) - 2(-432.8) - 0
    = 70.2 kJ/mol

    The numbers I have for these heats of formation are:

    Mg2+: -462.0
    Cl-: -167.4
    MgCl2: -641.8
    KClO3: -397.7
    KClO4: -432.8
     

    Attached Files:

  2. jcsd
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