Question

Using the following equation for the combustion of octane, calculate the heat associated combustion of 100.0 g of octane assuming complete combustion. The molar mass of octane is 114.33 g/mole. The molar mass of oxygen is 31.9988 g/mole.2C8H18+25O2→16CO2+18H2O;ΔH∘rxn = -11018 kJA. -11018 kJB. -4819 kJC. -602.3 kJD. -535.4 kJE. -385.5 kJ

Answer 1

Answer:

Option B. -4819 kJ

Explanation:

Equation of reaction:

$2C_{8} H_{18} + 25O_{2} \rightarrow 16CO_{2} + 18 H_{2} O$          Δ$H_{rxn} ^{0}$ = -11018 kJ

Mass of octane, m = 100.0 g

Molar mass of octane, MM = 114.33 g/mol

Number of mole, n = Mass/ Molar mass

Number of mole of octane, n = m/MM

n = 100/114.33

n = 0.8746 mols

From the chemical equation above

2 mols of octane produced -11018 kJ of heat

1 mol of octane produces (-11018/2) kJ of heat = -5509 kJ oh heat

Therefore, o.875 mols of octane will produce (-5509 * 0.8746) kJ oh heat = -4819 kJ of heat.