To determine which formula can be used to calculate the molar mass of water (H₂O), we need to understand the composition of a water molecule. A water molecule consists of:
- 2 hydrogen atoms
- 1 oxygen atom
To find the molar mass of water, we need to sum the contributions of the hydrogen atoms and the oxygen atom, taking into account their respective quantities in the molecule.
1. First, let's note the molar masses of individual atoms:
- The molar mass of hydrogen (H) is approximately 1 gram per mole.
- The molar mass of oxygen (O) is approximately 16 grams per mole.
2. Since a water molecule has 2 hydrogen atoms, we multiply the molar mass of hydrogen by 2:
- 2 × (molar mass of H) = 2 × 1 g/mol = 2 g/mol
3. There is only 1 oxygen atom in a water molecule, so we take the molar mass of oxygen directly:
- 1 × (molar mass of O) = 1 × 16 g/mol = 16 g/mol
4. To find the total molar mass of water, we sum the contributions from the hydrogen and oxygen atoms:
- Total molar mass of H₂O = (2 × molar mass of H) + (1 × molar mass of O)
- Total molar mass of H₂O = 2 g/mol + 16 g/mol = 18 g/mol
Based on this description, the correct formula that accurately represents the calculation of the molar mass of water is:
[tex]\[ 2 \times \text{molar mass of H} + \text{molar mass of O} \][/tex]
Thus, the correct option to calculate the molar mass of water (H₂O) is:
Option 3: [tex]\( 2 \times \text{molar mass of H} + \text{molar mass of O} \)[/tex]
This option correctly reflects the composition of the water molecule, including 2 hydrogen atoms and 1 oxygen atom.
