# Confused about mole ratio being relative or absolute

by Dorslek
Tags: absolute, confused, mole, ratio, relative
 P: 14 Let's start with a generalized example: 3A + 1B -> 2C For the mole amount next to each molecule, am I always to consider these as relative to one another or absolute? Most of the videos I have seen are describing the above as "for every 3 moles of A and 1 mole of B you get 2 moles of C". I believed at some point that these numbers were absolute however, after reading up on equilibrium I discovered that I was incorrect. So for a reaction such as this: I have a ratio of 2:1:3. If I used up 0.8 moles of the nitrogen, I read that I would use the ratio to discover that I would produce 0.4 moles of nitrogen and 1.2 moles of hydrogen. Would anyone care to explain this to me?
P: 156
 Quote by Dorslek If I used up 0.8 moles of the nitrogen, I read that I would use the ratio to discover that I would produce 0.4 moles of nitrogen and 1.2 moles of hydrogen.
Correct. A molar ratio is just that, a ratio. It's a ratio in the same way that 1:2 is the same as 0.5:1 or 2:4. Just because the reaction says 2NH3 doesn't mean you have to use 2 moles.
 PF Patron P: 347 .8NH3 x 1N2/2NH3= .4N2 .8NH3 x 3H2/2NH3= 1.2H2

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