Question

How many grams of O2 gas would you need to make 100grams of water?(H2O)

How many grams of H2 would you need to make 100grams of water?

Answer 1

The equation for the reaction of the formation of water from oxygen and hydrogen:

2H₂ + O₂ $\to$ 2H₂O

• According to the equation, we can determine the amounts of substances of H₂ and O₂:

$\nu$(H₂O) = $m/M$ = 100(g) / 18(g/mol) = 5.56 mol = $\nu$(H₂)

$\nu$ (O₂) = $\nu$ (H₂O) $• 1/2$ = 5.56(mol) • 1/2 = 2.78(mol)

• Then, we can calculate the masses of hydrogen and oxygen:

m(O₂) = $\nu • M$ = 2.78(mol) • 32(g/mol) = 88.96 g

m(H₂) = $\nu•M =$ 5.56(mol) • 2(g/mol) = 11.12 g

Answer: m(O₂)=88.96 g; m(H₂) = 11.12 g