Using the following balanced equation:
Ammonia is produced by the reaction of hydrogen and nitrogen
N2(g) + 3 H2(g) yields 2 NH3(g)

How many moles of N2 reacted if 0.66 mole of NH3 is produced?

How many moles of NH3 are produced when 2.7 moles of H2 reacts?

Hi!!


The balanced equation gives us the ratio between moles of products of
reaction and moles of reactives; in this case it tells us that for
each 2 moles of NH3 produced we need 1 mol of N2, so the ratio between
them for this reaction is 1/2, then for 0.66 moles of NH3 we will
need:
0.66 * 1/2 = 0.33 moles of N2.


In the same way when 3 moles of H2 react we obtain 2 moles of NH3, so
the ratio between them for this reaction is 2/3, then when 2.7 moles
of H2 react we will obtain:
2.7 * 2/3 = 1.8 moles of NH3


For references see:
"Chemical Reactions":
http://chemed.chem.purdue.edu/genchem/topicreview/bp/ch3/equations.html

"Stoichiometry Problems":
http://members.aol.com/profchm/stoic.html



I hope this helps you. Feel free to request for a clarification if you need it.

Regards,
livioflores-ga