5 g of hydrogen reacts with 32 g of oxygen to form moles of water

Options

A. 1
B. 2
C. 3
D. 4

Answer

To solve the question of how many moles of water are formed when 5 g of hydrogen reacts with 32 g of oxygen, we can follow these steps:

### Step 1: Write the balanced chemical equation
The balanced chemical equation for the reaction between hydrogen and oxygen to form water is:
\[ \text{2 H}_2 + \text{O}_2 \rightarrow \text{2 H}_2\text{O} \]

### Step 2: Calculate the number of moles of hydrogen (H₂)
To find the number of moles of hydrogen, we use the formula:
\[ \text{Number of moles} = \frac{\text{mass (g)}}{\text{molar mass (g/mol)}} \]

The molar mass of hydrogen (H₂) is approximately 2 g/mol. Therefore:
\[ \text{Number of moles of H}_2 = \frac{5 \text{ g}}{2 \text{ g/mol}} = 2.5 \text{ moles} \]

### Step 3: Calculate the number of moles of oxygen (O₂)
The molar mass of oxygen (O₂) is approximately 32 g/mol. Therefore:
\[ \text{Number of moles of O}_2 = \frac{32 \text{ g}}{32 \text{ g/mol}} = 1 \text{ mole} \]

### Step 4: Determine the limiting reagent
From the balanced equation, we see that 2 moles of H₂ react with 1 mole of O₂. We have:
- 2.5 moles of H₂
- 1 mole of O₂

To react completely with 1 mole of O₂, we would need 2 moles of H₂. Since we have 2.5 moles of H₂, we have more than enough hydrogen. Therefore, O₂ is the limiting reagent.

### Step 5: Calculate the moles of water produced
According to the balanced equation, 1 mole of O₂ produces 2 moles of H₂O. Since we have 1 mole of O₂, the moles of water produced will be:
\[ \text{Moles of H}_2\text{O} = 1 \text{ mole O}_2 \times \frac{2 \text{ moles H}_2\text{O}}{1 \text{ mole O}_2} = 2 \text{ moles H}_2\text{O} \]

### Final Answer
Thus, the number of moles of water formed is **2 moles**.

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