Question

Octane is the principal component of gasoline and has an enthalpy of combustion of -5430 kJ/mol. If the density of octane is 0.703 g/cm³, how many moles of octane must be burned to generate 1550 kJ of heat?

A. 0.284 moles
B. 0.567 moles
C. 1.131 moles
D. 2.262 moles

Answer 1

To generate 1550 kJ of heat, approximately 0.284 moles of octane must be burned.

Step-by-step explanation:

To determine how many moles of octane must be burned to generate 1550 kJ of heat, we need to use the enthalpy of combustion and the density of octane.

First, let's convert the density of octane from g/cm³ to g/mL. Since there are 1000 cm³ in 1 L, the density of octane is 0.703 g/cm³ × 1000 cm³/L = 703 g/L.

Next, we need to convert the enthalpy of combustion from kJ/mol to kJ/L. Since the enthalpy of combustion is -5430 kJ/mol, we can use the equation:

1 mol of octane = 703 g of octane = 5430 kJ of heat

x mol of octane = 1550 kJ of heat

Solving for x gives us:

x = (1550 kJ) × (1 mol/5430 kJ) × (703 g/1 mol) = 0.284 moles