Answer:
86 g Hâ‚‚
Explanation:
The reaction between hydrogen gas (Hâ‚‚) and oxygen gas (Oâ‚‚) to produce water (Hâ‚‚O) is described by the following balanced chemical equation:
2 H₂(g) + O₂(g) → 2 H₂O(g)
As we can see, 2 moles of Hâ‚‚ reacts with 1 mol of Oâ‚‚. We have to convert the moles to mass by using the molar mass (MM) of each compound:
MM(Hâ‚‚) = 1 g/mol x 2 = 2 g/mol
2 moles Hâ‚‚ = 2 mol x 2 g/mol = 4 g
MM(Oâ‚‚) = 16 g/mol x 2 = 32 g/mol
1 mol Oâ‚‚ = 1 mol x 32 g/mol = 32 g
Thus, 4 grams of Hâ‚‚ reacts with 32 g of Oâ‚‚. The stoichiometric ratio Hâ‚‚/Oâ‚‚ is 4 g Hâ‚‚/32 g Oâ‚‚. So, we multiply the stoichiometric ratio by the mass of Oâ‚‚ we have (688 g) to calculate the grams of Hâ‚‚ we need:
4 g Hâ‚‚/32 g Oâ‚‚ x 688 g Oâ‚‚ = 86 g Hâ‚‚
