How do I find out the moles of gas for Co2 and everything else

Question

3) In the combustion reaction of methane gas : CH4 (g) + O2 (g) --> CO2 (g) + 2 H2O (g)

4.0 X 10 exp 23 molecules of CH4 was used. Determine

(a) the moles of CO2 produced

(b) using your answer in (a), calculate the volume of CO2 produced at STP

(c) the volume of oxygen used in the reaction at STP

Answer 1

The FIRST thing you must do, is get a correctly balanced equation:

CH₄(g) + 2O₂(g) ==> CO₂(g) + 2H₂O(g) ... balanced equation

a) 4x10²³ molecules CH₄ x 1 mol CH₄/6.02x10²³ molecules x 1 mol CO₂/mol CH₄ = 0.67 moles CO₂

b) @STP each mol = 22.4 L. 0.67 mol x 22.4 L/mol = 15. L

c) 15 L CO₂ x 2 L O₂ / 1 L CO₂ = 30. L O₂