To determine how many moles of water are produced when starting with a certain amount of oxygen and sufficient hydrogen, we can use the balanced chemical equation:
\[ 2 \text{H}_2 + \text{O}_2 \rightarrow 2 \text{H}_2\text{O} \]
From the balanced equation, we can see the following ratios:
- 1 mole of \( \text{O}_2 \) produces 2 moles of \( \text{H}_2\text{O} \).
Next, we need to calculate the number of moles of \( \text{O}_2 \) available. The molar mass of \( \text{O}_2 \) is given as 32 g. If we assume we start with 64 grams of \( \text{O}_2 \):
\[ \text{Moles of } \text{O}_2 = \frac{\text{mass}}{\text{molar mass}} = \frac{64 \text{ g}}{32 \text{ g/mol}} = 2 \text{ moles of } \text{O}_2 \]
Since 1 mole of \( \text{O}_2 \) produces 2 moles of \( \text{H}_2\text{O} \):
\[ 2 \text{ moles of } \text{O}_2 \times 2 = 4 \text{ moles of } \text{H}_2\text{O} \]
Therefore, starting with 64 grams of oxygen and a sufficient amount of hydrogen, you would produce 4 moles of water.
Thus, the answer is 4.