[jessiker4117]

  ok, here is the question

 Methane,the chief component of narural gas,burns in oxygen according to the equation

  CH(small 4)(g) + 2 O(small 2)(g)________> CO(small 2)(g) + 2H(small 2)O(g)

  If 7 moles of CH(small 4) react with an unlimited amount of oxygen, how many moles of H(small 2)O(g) will be produced?

 my answer : 14 b/c i just guessed b/c my book doesn't explain in this kind of problem.. i would really appreciate if you could help me, thanx.

[Donaldson Tan]

CH₄ + 2O₂ -> CO₂ + 2H₂O

Under complete combustion, the molar ratio of oxygen to methane is 2:1, ie. every mole of methane reacts with 2 moles of oxygen. In excess oxygen, complete combustion takes place. Since all 7 moles of methane undergoes complete combustion, 14 moles of oxygen therefore must be consumed by the reaction.