How many moles of water can be made from 4 moles of oxygen gas and....?

this is actually a pretty simple all you have to do is set up the mole to mole ratio .... the first thing you want to do is balance the equation 2H2 + O2 yields 2H20 .... hydrogen gas in it's natural form is H2 gas and oxygen is O2 gas .... when these combine you get 2h2O so their is the mole to mole ratio of 1 mole of oxygen makes 2 moles of h20.... from oxygen you have 4 moles and from 1 mole of O2 gas you get 2 moles of H20 ... you want to set up the equation to make things cancle out and only be left with moles of H2O .... so you are givin 4 moles of 02 if you divide by 1 mole of 02 and multiply by 2 moles of h20 you will get 8 moles of h20 remember i picked up the mole to mole ratio from the balanced equation once you know the moles of h20 you can set it up to get it's m by multiplying the moles by the molecular weight of the h20 molecule (18g) to get 144g of h20 ... the way to find the limiting reactant is to repeate this process with h2 gas and which ever one produces the least amount of water is your limiting reactant O2 gas should be the limiting reactant diotomic molecues are H, N, O, F, CL, BR, I these you will just have to memorize