Ethanol (ch3ch2oh) has been suggested as an alternative fuel source. ethanol’s enthalpy of combustion is hcomb = –1368 kj/mol.

what volume of ethanol (d = 0.789 g/ml) is required to produce the same amount of energy as 1 gallon of gasoline, which can be modeled as isooctane (c8h18, d = 0.703 g/ml) with an energy density of 32.9 kj/ml? (1 gal = 3.785 l)

5.3072 Liters of  volume of ethanol is required.

Explanation:

Volume of isooctane = 1 gal = 3.785 L

3.785 L =3.785 × 1000 mL= 3,785 mL

Energy density of isooctane = 32.9 kJ/mL

Energy produced on combustion of 3,785 mL of isooctane :

Moles of ethanol which will produce same amount of energy 'E' as 1 gallon of iosooctane = n

Ethanol’s enthalpy of combustion =

Energy released when 1 mole of ethanol is combusted = 1,368 kJ/mol

n = 91.03 mole

Mass of 91.03 moles of ethanol , m= 91.03 mol × 46 g/mol = 4,187.38 g

Volume of ethanol = V

Density of ethanol = d = 0.789 g/mL

5.3072 Liters of  volume of ethanol is required.

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