4NH3(g)+3 O2(g)=2N2(g)+6H2 O(g)

Question

How many moles of water are produced when 14.8 moles of oxygen completely react?

Answer 1

From the balanced equation you see that 3 moles of O₂ produce 6 moles of H₂O.  So, it is a simple proportion.

3 O₂/14.8 O₂ = 6 H₂O/x H₂O

x = 29.6 moles H₂O