Material balances for combustion of octane

One of the most common chemical reactors found around us is the car engine.  It takes gasoline and reacts it with air to release chemical energy, which in turn is transformed into mechanical energy.  Emissions from your car’s engine have been an environmental concern for many years.  

Using the concepts of material balances, determine how much (in moles and lbs) air is needed and CO2, N2, CO, and H2O are emitted for every gallon of gasoline burned in your car’s engine.  Assume that gasoline, a mixture of many hydrocarbons, can be modeled as pure octane (C8H18).  Assume that 90% of the octane is turned into carbon dioxide and water, and 10% of the octane is turned into carbon monoxide and water.  No excess air is involved in the reaction, meaning only enough air to provide the needed oxygen is introduced into the engine.  Also assume the nitrogen in the air does not react at the temperature of your engine.  Use the variables nO2, nN2, nCO, nCO2, nN2, and nH2O to represent the number of moles of each component in various streams.
C8H18 + O2 arrow CO2 + CO+ H2O