Chapter 5, Problem 120AP

The so-called hydrogen economy is based on hydrogen produced from water using solar energy. The gas is then burned as a fuel:

A primary advantage of hydrogen as a fuel is that it is nonpolluting, A major disadvantage is that it is a gas and therefore is harder to store than liquids. Calculate the number of moles of ${\text{H}}_{\text{2}}$ required to produce an amount of energy equivalent to that produced by the combustion of a gallon of octane $\left({\text{C}}_{\text{8}}{\text{H}}_{\text{18}}\right)\text{.}$ The density of octane is $\text{2}\text{.66 kg/gal}\text{.}$ and its standard enthalpy of formation is $\text{-249}\text{.9 kJ/mol}\text{.}$