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Homework Help: Thermochemical question about the heat of combustion of a hydride

  1. May 27, 2012 #1
    1. The problem statement, all variables and given/known data
    What is the heat released by the complete combustion of 22.4x10^3 litres of FeTiH2 - a fuel used in hydrogen cars -, producing liquid water?

    2. Relevant equations
    ΔH°(reaction) = ΔH°f(products) - ΔH°f(reactants)

    3. The attempt at a solution
    1 mol FeTiH2 - 22,4 L (STP)
    x - 22.4x10^3 litres
    x = 1000 moles of FeTiH2

    I guess the equation for the combustion is:
    1000 FeTiH2(g) + 2250 O2(g) = 1000 H2O(l) + 500 Fe2O3(s) + 1000 TiO2(s)

    Using the Hess's Law:
    ΔH°(reaction) = 1000ΔH°f(H2O,l) + 500ΔH°f(Fe2O3,s) + 1000ΔH°f(TiO2,s)
    - 1000ΔH°f(FeTiH2,g) - 2250ΔH°f(O2,g)
    ΔH°(reaction) = - 285800 - 824200 - 945000 - 1000ΔH°f(FeTiH2,g) - 0

    I'm having trouble finding the heat of formation of FeTiH2. There're some heat of formation around Google, but I haven't found one at 1 atm pressure. So I guess there must be another way to resolve this problem :tongue:

    The answer is - 2.86x10^5 kJ/mol
  2. jcsd
  3. May 27, 2012 #2


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    Staff: Mentor

    I don't see how FeTiH2 can be gaseous. I expect solid, so the amount given as a volume (without density) doesn't make much sense.
  4. May 27, 2012 #3
    Oh yes, my bad :tongue: But anyway, I can't find the heat of formation :frown:
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