chem
posted by julia .
consider the following balance chemical equation:
2NH3(g)+3CuO(s)=N2(g)+3Cu(s)+3H2O(g)
if 18.1grams of ammonia reacts with 90.4 grams of copper(II) oxide, which is the limitting reagent?? what is the theorectical yield of nitrogen gasd? if 8.52 g of N2 are formed, what is the % yield of nitrogn gas??
please check if is correct....
limitting reagent is NH3 with 2.13 mol N2
theoretical yield nitrogen gas is 59.68g N2
percent yield of nitrogen gas is 14.28%
please i need to know what i'm doing wrong..thank you....

No, it isn't correct. From the few numbers you show, I have been able to guess that you have the moles right but you used the wrong conversion to convert to moles N2.
moles NH3 = 18.1/17 = about 1.06
moles N2 = 1.06 x (1 mole N2/2 moles NH3) = 1.06/2 = 0.53 moles N2.
moles CuO = 90.4/79.545 = 1.136
moles N2 formed = 1.136 x (1 mole N2/3 moles CuO) = 1.136*(1/3) = 0.379 moles N2.
I will leave it at that and let you finish but it is important for you to understand that you should have divided by 2 and 3 instead of multiplying by 2 and 3 (at least that's what I think you did). 
ok..I see what i did wrong...thank u..ur the best!!!