One kmol of methane (CH4) is burned with an unknown amount of air. If the combustion is

Question:

One kmol of methane (CH4) is burned with an unknown amount of air. If the combustion is assumed complete and there are 2 kmol of free O2 in the products, determine.
(a) The percent theoretical air used.
(b) The excess air used (in percent).
(c) The equivalence ratio.