The molecular weight of water (H2O) is approximately 18.015 grams per mole. This value is obtained by adding the atomic weights of the constituent elements of water.
Water is composed of two hydrogen (H) atoms and one oxygen (O) atom. The atomic weight of hydrogen is about 1.008 grams per mole, and the atomic weight of oxygen is approximately 16.00 grams per mole. By calculating:
- 2 × 1.008 = 2.016 (for the two hydrogen atoms)
- 1 × 16.00 = 16.00 (for the one oxygen atom)
When you add these together: 2.016 + 16.00 = 18.016 grams per mole. Rounding it off gives us a molecular weight of about 18.015 grams per mole.
This molecular weight is essential in various scientific calculations and applications, especially in chemistry and biology, where water is a critical solvent and reactant.