Question

How much oxygen gas can I make from a `9*kg` mass of water?

Answer 1

`H_2O(g) rarr 1/2O_2(g) + H_2(g)`

Explanation:

You have `90xx10^3*g` of water. This represents a MOLAR quantity of `(90xx10^3*g)/(18*g*mol^-1)=??mol`.

The number of moles of oxygen gas, `O_2`, is half this molar quantity by the stoichiometric equation.

And of course each mole of oxygen gas has a mass of `32*g`. From where am I getting these masses? Do you have to learn them?