Question

Kerosene, a common space-heater fuel, is a mixture of hydrocarbons whose average formula is C12H26.

a) Determine the balanced equation, using the simplest whole-number coefficients, for the complete combustion of kerosene (C12H26) to gases. Include physical states of each reactant and product.

b) If Detla H rxn= -1.50 * 10^4 kJ for the combustion equation as written in part (a). determine delta H t of kerosene in kJ/mol.

c) Calculate the heat produced by the combustion of 0.82 gal of kerosene (density of kerosene= .749 g/mL)

d) How many gallons of kerosene must be burned for a kerosene furnace to produce 1,143 Btu (1 Btu= 1.005 kJ)?

Answer 1

a) combustion will be

2C₁₂H₂₆ (l) + 37 O₂ (g) -> 24CO₂ (g) + 26H₂O (l)

In terms of simplest whole number

b) The deltaH of reaction = -1.50 X 10⁴ kJ

this is for two moles of kerosene, the deltaH of reaction for one mole = -1.50 X 10⁴ kJ /2 = -7.5 X 10³ kJ / mol

c) Molar mass of kerosene = 12 X 12 + 26 = 170 g / mole

1 gal = 3785.41 mL

0.82 gal = 3104 mL

Mass of 0.82gal = density X volume = 0.749 X 3104 = 2324.896 grams

moles of kerosene in 2324.896g = Mass / Molar mass = 2324.896 grams / 170 = 13.68 moles

Heat produced = enthalpy per mole X moles =  -7.5 X 10³ kJ / mol X 13.68 = -1.026 X X 10⁵ kJ

d) 1,143 Btu = 1.005 X 1143 kJ = 1148.72 kJ

To produce -1.026 X X 10⁵ kJ heat 0.82 gallons need to be burnt

So for 1kJ heat = 0.82 / 1.026 X X 10⁵ gallons need to be burnt

for 1148.72kJ = 0.82 X 1148.72 / 1.026 X X 10⁵ = 918.1 X 10^-5 gallons = 0.00918 gallons