How many moles of water molecules are present in 3.8 x `10^(-8)` g of water?

Explanation

To find the number of moles of water molecules present in 3.8 x 10^(-8) g of water, we can follow these steps:

### Step 1: Determine the molar mass of water (H₂O)
Water consists of two hydrogen atoms and one oxygen atom. The atomic masses are approximately:
- Hydrogen (H) = 1 g/mol
- Oxygen (O) = 16 g/mol

Calculating the molar mass of water:
\[ \text{Molar mass of } H_2O = (2 \times 1) + (1 \times 16) = 2 + 16 = 18 \text{ g/mol} \]

### Step 2: Use the formula to find the number of moles
The number of moles (n) can be calculated using the formula:
\[ n = \frac{\text{mass (g)}}{\text{molar mass (g/mol)}} \]

### Step 3: Substitute the values into the formula
We have:
- Mass of water = 3.8 x 10^(-8) g
- Molar mass of water = 18 g/mol

Substituting these values into the formula:
\[ n = \frac{3.8 \times 10^{-8} \text{ g}}{18 \text{ g/mol}} \]

### Step 4: Perform the calculation
Now, we can calculate the number of moles:
\[ n = \frac{3.8 \times 10^{-8}}{18} = 2.1111 \times 10^{-9} \text{ moles} \]

### Step 5: Round the answer
Rounding to three significant figures, we get:
\[ n \approx 2.11 \times 10^{-9} \text{ moles} \]

### Final Answer
The number of moles of water molecules present in 3.8 x 10^(-8) g of water is approximately **2.11 x 10^(-9) moles**.

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