# Thermochemical question about the heat of combustion of a hydride

1. May 27, 2012

### pollycampos

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. May 27, 2012

### 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.

3. May 27, 2012

### pollycampos

Oh yes, my bad :tongue: But anyway, I can't find the heat of formation