If you burn 52.8g of hydrogen and produce 472g of water, how much oxygen reacted?

2H₂ + O₂ → 2H₂O

According to the law of conservation of mass:
(Mass of H₂ reacted) + (Mass of O₂ reacted) = Mass of H₂O produced
(52.8 g) + (Mass of O₂ reacted) = 472 g
Mass of O₂ reacted = (472 - 52.8) g = 419.2 g ≈ 419 g
(to 3 sig. fig.)

Hydrogen + Oxygen ➜ water
2H₂(g) + O₂(g) ➜ 2H₂O(l) + 572 kJ (286 kJ/mol)
molecular weights
H = 1.008
O = 15.999
2H₂ = 4.032
O₂ = 31.998
2H₂O = 36.03

2 mole of H₂ + 1 moles of O₂ ➜ 2 moles of H₂O
4.03 grams of H₂ + 32 grams of O₂ ➜ 36.03 grams of H₂O


If you burn 52.8g of hydrogen and produce 472g of water, how much oxygen reacted?

first check the numbers
ratio of water to hydrogen is 36.03/4.03 = 8.94
you have 472/52.8 = 8.94, so those are ok.

ratio of oxygen to hydrogen is 32/4.03
32/4.03 = x/52.8
x = 419 g

check 52.8+419 = 472 g ok