How many grams of water could be made from 5.0 mol #H_2# and 3.0 mol #O_2#?
You need a stoichiometric equation to represent the formation of water:
Given the stoichiometry, dihydrogen is in deficiency, and ONLY
And this represents a mass of
What mas of dioxygen will remain after reaction?
The balanced equation is:
From this you can see that 5 moles of hydrogen gas would react with 2.5 of the available 3 moles of oxygen gas, to form 5 moles of water.
The molar mass of water is 18 g/mol, so you would end up with 5 x 18 = 90 g of water.