Question

Given 6.0 mol of N2 are mixed with 12.0 mol of H2. Equation: N2 + 3H2--> 2NH3

Which chemical is in excess? What is the excess in moles?
Theoretically, how many moles of NH3 will be produced?
If the percentage yield of NH3 is 80%, how many moles of NH3 are actually produced?

Please step it out from the very beginning! I am so lost!

Answer 1

You should compare amount of substances given in equation and amounts given.

Equation shows that you need three times more Hydrogen than Nitrogen.
You estimate, which one ends in reaction. Another chemical is in excess.

Then you think how many moles you get when you know which is limiting reactant.
One mole Nitrogen gives two mole ammonia and three moles Hydrogen gives
two moles ammonia. You can use proportions in it.

If percentage yield is 80 %, you multiply amount of substance of ammonia by 0.8.