Chapter 6, Problem 6.93QP

Ethanol (C₂H₅OH) and gasoline (assumed to be all octane, C₈H₁₈) are both used as automobile fuel. If gasoline is selling for $4.50/gal, what would the price of ethanol have to be in order to provide the same amount of heat per dollar? The density and $\Delta H_{\text{f}}^{\text{o}}$ of octane are 0.7025 g/mL and −249.9 kJ/mol and of ethanol are 0.7894 g/mL and −277.0 kJ/mol, respectively. 1 gal = 3.785 L.