You produce 3.6 mol CO2, how many moles CH4 were used?

Question

CH4 + 2O2 —> CO2 + 2H2O

partial answer: 3.X mol CH4

Answer 1

Madison - According to this balanced chemical equation, one mole of CH4 produces one mole of CO2. Therefore they are in a 1:1 molar ratio for all calculations. In this case, we can say it takes one mole of CH4 to produce one mole of CO2. Another way to say this is that we can produce 1 mol CO2 per 1 mol CH4 used.

Since you are producing 3.6 mol CO2, you can calculate the starting moles of CH4 with the simple mole-to-mole ratio: 1 mol CH4 / 1 mol CO2 as a conversion factor.

Taking 3.6 mol CO2 x 1 mol CH4 / 1 mol CO2 = 3.6 mol CH4

(after canceling out the moles of CO2 on the top and bottom of the calculation)

Doing these types of calculations is easy once you focus on the definitions and relationships, and learn the method of "dimensional analysis" or "unit conversion". You can do the same types of calculations with grams and molecular weight by creating conversion factors and using them in the correct way to cancel out the units you want to get rid of, and get to the units you want to be in! Hope that concept helps - good luck!