How many moles of H2O can be formed when 4.5 moles of NH3 react with 3.2 moles of O2? NH3 + O2 yields NO + H2O

A. 3.8 mol H2O

B. 4.8 mol H2O

C. 6.4 mol H2O

D. 6.8 mol H2O

4 NH3 + 5 O2 = 4 NO + 6 H2O

the ratio between NH3 and O2 is 4 : 5

moles O2 required = 4.5 x 5 / 4 = 5.6

because we have only 3.2 moles of O2 this is the limiting reactant

the ratio between O2 and H2O is 5 : 6

moles H2O = 3.2 x 6 / 5 = 3.8