Question

How many moles of oxygen are needed to produce 3.0 moles of water?
2 H2 + O2 → 2 H2O
Please show some work so I can know how to do it in the future! Please and thank you.

Answer 1

Answer: 1.5 moles O2

Explanation:

The number of moles of each reactant and product is the number in front to the molecule when the equation is balanced.

You know that 1 mole of O2 gives you 2 moles of H2O

So you can set up a proportion using that.

1 mole O2. X moles O2

-------------- = -------------------

2 moles H2O. 3 moles H2O

Then cross multiply

2x=3

X=3/2 Or 1.5

So you need 1.5 moles O2 to get 3 moles of H2O.