What is the molar mass of water (H₂O)?

To determine the molar mass of water (H₂O), we need to calculate the mass contributions of its constituent elements: hydrogen and oxygen.

Water consists of two hydrogen (H) atoms and one oxygen (O) atom. The molar mass of hydrogen is approximately 1 g/mol, so for two hydrogen atoms, the total mass contribution is:

2 H atoms × 1 g/mol = 2 g/mol.

The molar mass of oxygen is about 16 g/mol. Therefore, the total mass contribution from one oxygen atom is:

1 O atom × 16 g/mol = 16 g/mol.

Now, we add the contributions from hydrogen and oxygen together:

2 g/mol (from hydrogen) + 16 g/mol (from oxygen) = 18 g/mol.

Thus, the molar mass of water (H₂O) is 18 g/mol, making this the correct answer. Understanding the composition of molecules is essential in chemistry, especially when calculating molar masses for various substances.