Question

11. Using the following equation for the combustion of octane, calculate the amount of grams of carbon dioxide formed from 100.0 g of octane. C8H18 + O2 → CO2 + H2O ΔH°rxn = -11018 kJ

Answer 1

molar mass of octane = 114 g
number of mol of octane = (given mass)/(molar mass)
= 100/114
= 0.877 mole

reaction taking place is
2C8H18 + 17O2 → 8CO2 + 18H2O
according to reaction
2 mol of C8H18 give 8 mol of CO2
1 mol of C8H18 give 8/2 mol of CO2
0.877 mol of C8H18 give (8/2)*0.877 mol of CO2
number of mol of CO2 formed = 3.51 mol

molar mass of CO2 = 44 g/mol
mass of CO2 formed = (number of mol of CO2 formed)*(molar mass of CO2)
= 3.51*44
= 154.4 g

Answer : 154.4 g