# How many moles of water are made from the complete reaction of 2.2 moles of oxygen gas with hydrogen gas in the reaction 2H_2 + O_2 -> 2H_2O?

$4.4 m o l {H}_{2} O$
The equation says that for every $1 {O}_{2}$, there are $2 {H}_{2} O$ produced.
Therefore, if you have $2.2 {O}_{2}$, you must have $2.2 \cdot 2 {H}_{2} O$, or $4.4$ moles of ${H}_{2} O$.