chemistry
posted by jhennel .
Given a sufficient supply of nitrogen gas, how many moles of ammonia gas will be produced from 10.8 moles of hydrogen gas?

First you write an equation, then balance it.
N2 + 3H2 ==> 2NH3
10.8 moles H2 x (2 moles NH3/3 moles H2) = mols NH3.
Note that the fraction I used converts moles of one thing into moles of another. Second thing to notice is that the numbers in the fraction are the same as the coefficients in the balanced equation. Third thing to notice is that the denominator of the fraction cancels the numerator of what I started with. Finally, the numerator of the fraction is the unit of the material I want to keep. 
HAHAHA thank you!

The answer is 7.2 NH3