Grams of hydrogen and oxygen found in 100 grams of water

Question

 Suppose you wanted to make 100 grams of water.

How many grams of hydrogen and oxygen will you need?

Then justify if your answer is reasonable or not?

Answer 1

Couple of ways to approach this problem.

(1). Percent composition

H₂O = 2 H + 1 O = 2 g H + 16 g O = total of 18 g

%H = 2 g / 18 g (x100%) = 11.11% H

%O = 16 g / 18 g (x100%) = 88.89% O

If you have 100 g H₂O, the amount of H and O is found as follows:

100 g H₂O x 11.11% H = 11.11 g H

100 g H₂O x 88.89% O = 88.89 g O

(2). gram -> mole -> gram

100 g H₂O x 1 mol H₂O / 18 g = 5.56 mols H₂O

5.56 mols H₂O x 2 mols H / mol H₂O x 1 g H / mol H = 11.1 g H

5.56 mols H₂O x 1 mol O / mol H₂O x 16 g O / mol O = 88.9 g O