Question

The complete combustion (reaction with oxygen) of liquid octane (c8h18) a component typical of the hydrocarbons in gasoline, produces carbon dioxide gas and water vapor. what is the coefficient of carbon dioxide gas in the balanced equation for the reaction? (balance the equation with the smallest possible whole number coefficients.)

Answer 1

During complete combustion, the hydrocarbon reacts with oxygen (O2) to from carbon dioxide (CO2) and water (H2O). For the combustion of one molecule of octane, 8 molecules of CO2 and 9 molecules of H2O must be formed to account for all the atoms of carbon and hydrogen in the octane. This requires 25 atoms of oxygen, or 12.5 molecules of O2: C8H18+12.5*O2=9*H2O+8*CO2 Multiply both sides by 2 to obtain whole number coefficients: 2*C8H18+25*O2=18*H2O+16*CO2 The coefficient of carbon dioxide in the balanced equation is 16.