Question

3 attempts left Check my work Be sure to answer all parts. Isooctane (CgHis; d=0.692 g/mL) is used as the fuel during a test of a new automobile engine. How much energy (in kJ) is released by complete combustion of 29.7 gal of isooctane to gases (AH' = -5.44 x 103 kJ/mol)? Enter your answer in scientific notation. rxn * 10 kJ

Answer 1

ΔHorxn = -5.44 x 103 kJ/mol

V = 29.7 gal

As 1 gal = 3785.41 mL

So, 29.7 gal = 112426.7 mL

V =  112426.7 mL

Energy released = ΔHorxn n

Mass = Density x Volume = 0.692 g/mL x 112426.7 mL = 77799.27 g

Molar mass of isooctane = 114.2 g/mol

Number of moles, n = Mass of isooctane/Molar mass = 77799.27 g/114.2 g/mol = 681.25 mol

Therefore, Energy released = ΔHorxn n

= -5.44 x 103 kJ/mol x 681.25 mol

= 3706000 kJ = 3.706 x 106 kJ