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Anonymous asked in Science & MathematicsChemistry · 9 years ago

Hess's Law - Enthalpy?

Hess's Law Practice Problem: Calculate the heat of reaction of the following reaction using the thermochemical data in the table below.

FeO(s) +CO(g) Fe(s) + CO2(g)

Thermochemical Data:

Reaction Heat of Reaction (deltaH)

(kJ/mol)

Fe2O3(s) + 3 CO(g) 2 Fe(s) + 3 CO2(g) -28

3 Fe2O3(s) + CO(g) 2 Fe3O4(s) + CO2(g) -59

Fe3O4(s) + CO(g) 3 FeO(s) + CO2(g) 38

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  • 9 years ago
    Favorite Answer

    Fe2O3(s) + 3 CO(g) ---> 2 Fe(s) + 3 CO2(g) -28

    3 Fe2O3(s) + CO(g) ---> 2 Fe3O4(s) + CO2(g) -59

    Fe3O4(s) + CO(g) ---> 3 FeO(s) + CO2(g) 38

    flip second

    flip third

    Fe2O3(s) + 3 CO(g) ---> 2 Fe(s) + 3 CO2(g) -28

    2 Fe3O4(s) + CO2(g) ---> 3 Fe2O3(s) + CO(g) +59

    3 FeO(s) + CO2(g) ---> Fe3O4(s) + CO(g) -38

    times first by 3

    times third by 2

    3Fe2O3(s) + 9 CO(g) ---> 6 Fe(s) + 9 CO2(g) -84

    2 Fe3O4(s) + CO2(g) ---> 3 Fe2O3(s) + CO(g) +59

    6 FeO(s) + 2CO2(g) ---> 2Fe3O4(s) + 2CO(g) -76

    Add. What you wind up with is this:

    6FeO(s) +6CO(g) ---> 6Fe(s) + 6CO2(g)

    So add the enthalpies, divide by 6 and you have your answer.

    More problems of this type:

    http://www.chemteam.info/Thermochem/HessLawIntro1....

  • 4 years ago

    Enthalpy's textbook defenition is the warmth replace of the systen while a million mole of the substance reacts with oxygen to form products decrease than STP (298 ok and a million atm.) It fairly measures "warmth", it quite is usually a sort of power. Hess's regulation is changing around enthalpy reaction formations to be certain the comprehensive enthalpy replace over the direction of the reaction. fairly, taking some smaller reactions and mixing them in an simple way.

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