Respuesta :
Using the following equation for the combustion of octane, calculate the heat associated with the 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.
[tex]2C_8H_{18}+25O_2\rightarrow 16CO_2+18H_2O[/tex] ΔH°rxn =-11018 kJ
A) -535.4 kJ
B) -4819 kJ
C) -602.3 kJ
D) -385.5 kJ
E) -11018 kJ
Answer: B) -4819 kJ
Explanation:
To calculate the moles :
[tex]\text{Moles of solute}=\frac{\text{given mass}}{\text{Molar Mass}}[/tex]
[tex]\text{Moles of octane}=\frac{100.0g}{114.33g/mol}=0.8747moles[/tex]
[tex]2C_8H_{18}+25O_2\rightarrow 16CO_2+18H_2O[/tex] ΔH°rxn =-11018 kJ
According to stoichiometry :
2 moles of octane release = 11018 kJ
Thus 0.8747 moles of octane will release =[tex]\frac{11018}{2}\times 0.8747=4819kJ[/tex]
Heat released is given as negative sign.
Thus the heat associated with the combustion of 100.0 g of octane assuming complete combustion is -4819 kJ
