Answer:
Rebecca, as I used to tell my chemistry students, the key to ANY stoichiometry problem is to first write the balanced equation. Even if you think you can solve the problem in your head. In your question, you know your two reactants and you know your product. Your question itself provides the unbalanced equation:
H2 + O2 → H2O
But the oxygen atoms come in packages of two. Currently the there are two oxygen atoms on the left and only one on the right. Let’s fix that:
H2 + O2 → 2 H2O
So we have the same number of oxygen atoms left and right, but now there are not enough hydrogen atoms on the left. Let’s fix that as well:
2 H2 + O2 → 2 H2O
Our equation is balanced! As sometimes happens, the answer to the question is staring us in the face. Two hydrogen molecules would give us two molecules of water. Two dozen hydrogen molecules would give us two dozen molecules of water. A mole is a number like a dozen only much bigger. Two moles of hydrogen molecules will give us two moles of water molecules.
Explanation:
hope this helps
