Butane $(C_4{H}_{10})$ is bumed with air. No carbon monoxide is present in the combustion products.

Use a degree$-$of$-$freedom analysis to prove that if the percentage excess air and the percentage

conversion of butane are specified, the molar composition of the product gas can be determined.

Calculate the molar composition of the product gas for each of the following three cases:

a$)$ Theoretical air supplied, $100\%$ conversion of butane,

b$)25\%$ excess air, $100\%$ conversion of butane,

c$)25\%$ excess air, $90\%$ conversion of butane.