Question

How many grams of h20 are produced when 2.50 moles of oxygen are used?

Answer 1

Molecular formula of water is H2O

Thus, one atom of 'O' combines with 2 atoms of 'H' for form 1 molecule of H2O

Here, atomic weight of O = 16 g/mol
and, molecular weight of H2O = 18 g/mol

Now,1 mole of O (16 g/mol) ≡ 1 mole of water (18 g/mol)
∴ 2.5 mole of O (40 g/mol) ≡ 2.5 moles of water (45 g/mol)

Answer: 45 grams of H2O are produced when 2.50 moles of oxygen are used

Answer 2

Answer is: 90 grams of water are produced.

Balanced chemical reaction: 2H₂ + O₂ → 2H₂O.
n(O₂) = 2.50 mol.
From chemical reaction: n(O₂) : n(H₂O) = 1 : 2.
n(H₂O) = 2 · 2.50 mol.
n(H₂O) = 5.00 mol; amount of substance.
M(H₂O) = 2 · 1 g/mol + 16 g/mol.
M(H₂O) = 18 g/mol; molar mass.
m(H₂O) = n(H₂O) · M(H₂O).
m(H₂O) = 5 mol · 18 g/mol.
m(H₂O) = 90 g; mass of substance.