A sample contains 18.0 g of water (H_2O). How many moles of molecules are present in this sample?

• A. 2.00 mol
• B. 9.00 mol
• C. 1.00 mol
• D. 0.50 mol

Answer: (C)

Verified step by step guidance

1. Identify the given information: the mass of water (H\_2O) is 18.0 g.
2. Recall the molar mass of water. Calculate it by adding the atomic masses of hydrogen and oxygen: Molar mass of H\_2O = (2 \times 1.008) + 16.00 g/mol.
3. Use the formula to find moles: \(\text{moles} = \frac{\text{mass}}{\text{molar mass}}\).
4. Substitute the known values into the formula: \(\text{moles} = \frac{18.0 \text{ g}}{\text{molar mass of H\_2O}}\).
5. Perform the division to find the number of moles of water molecules in the sample.