Question

Pentane is a small liquid hydrocarbon, between propane and gasoline in size at C5H12. The density of pentane is 0.626 g/mL and its enthalpy of combustion is ΔH°comb = –3535 kJ/mol. Estimate the fuel value and the fuel density of pentane.

Answer 1

Answer : The fuel value and the fuel density of pentane is, 49.09 kJ/g and $3.073\times 10^4kJ/L$ respectively.

Explanation :

Fuel value : It is defined as the amount of energy released from the combustion of hydrocarbon fuels. The fuel value always in positive and in kilojoule per gram (kJ/g).

As we are given that:

$\Delta H^o_{comb}=-3535kJ/mol$

Fuel value = $\frac{\Delta H^o_{comb}}{\text{Molar mass of pentane}}$

Molar mass of pentane = 72 g/mol

Fuel value = $\frac{3535kJ/mol}{72g/mol}$

Fuel value = 49.09 kJ/g

Now we have to calculate the fuel density of pentane.

Fuel density = Fuel value × Density

Fuel density = (49.09 kJ/g) × (0.626g/mL)

Fuel density = 30.73 kJ/mL = $3.073\times 10^4kJ/L$

Thus, the fuel density of pentane is $3.073\times 10^4kJ/L$