Answer:
48 grams
Step-by-step explanation:
The chemical equation for the reaction is the following:
2 H₂ + O₂ → 2 H₂O
That means that 2 moles of H₂ react with 1 mol of O₂ to produce 2 moles of H₂O. We convert the moles of oxygen (O₂) by using the molecular weight (MW) as follows:
MW(O₂) = 16 g/mol x 2 = 32 g/mol
mass of O₂ = 1 mol x 32 g/mol = 32 g
So, we have the following stoichiometric ratio: 32 g O₂/2 moles H₂. We have 3 moles of hydrogen (H₂), so we multiply the moles by the stoichiometric ratio to calculate how many grams are needed:
3 moles H₂ x 32 g O₂/2 moles H₂ = 48 g O₂
Therefore, 48 grams of O₂ are needed to react with 3 moles of H₂.