I have been told that applying POAC in any equation means conserving the number of moles of an element in both reactant and product . For example : $$\ce{H2 + O2 -> H2O}$$ Here when we apply POAC on oxygen we write :
Equation 1 :
No. Of Atoms(or moles) of "O" in reactant = No. Of Atoms(or moles ) of "O" in product
Equation 2: (obtained from equation 1)
2(moles of $\ce{O2}$) = 1(moles of $\ce{H2O}$)
Where equation 2 gives us the necessary data required in solving questions of stoichiometric calculations . I understand how equation 2 comes from equation 1 but I don't understand why equation 1 is correct even when the chemical equation is unbalanced ?
As I think equation 1 can be applied only when the chemical equation is balanced . As here :
No. Of Atoms of "O" in reactant =2
No of Atoms of "O" in product = 1
Thus by equation 1 we can say that $1=2$ .
And my book says POAC can be applied even when equation is not balanced . So here equation is not balanced and when I apply POAC I get $1=2$ . So what's is wrong with my reasoning?