Chemistry
posted by Destinee .
given the balanced equation representing a reaction:
4NH3+5O2>4NO+6H2O
what is the minimum number of moles of O2 that are needed to completely react with 16 moles of NH3?
(1)16 mol
(2)20.mol
(3)64 mol
(4)80. mol i think its 2 but im not sure.

4NH3+5O2>4NO+6H2O
The formula tells us that 4 moles NH3 = 5 moles O2. So use ratio/proportion OR dimensional analysis methods.
16 moles NH3 x (5 moles O2/4 moles NH3) = ??
Note how the unit in the denominator cancels with the unit in the numerator LEAVING the unit (moles O2) you want. If the fraction is placed the other way the units don't cancel. 
20