Water Molar Mass MW Calculator

Water (H₂O) Molar Mass Calculation:

\[ MW = (2 \times 1.008) + 15.999 = 18.015 \text{ g/mol} \]

Molar Mass (MW):

Unit Converter ▲

Unit Converter ▼

From:	To:

1. What is Molar Mass?

Molar mass is the mass of one mole of a substance, typically expressed in grams per mole (g/mol). For chemical compounds, it's the sum of the atomic masses of all atoms in the molecule.

2. How is Water's Molar Mass Calculated?

The molar mass of water (H₂O) is calculated as:

\[ MW = (2 \times \text{Atomic mass of H}) + (1 \times \text{Atomic mass of O}) \]

Where:

Atomic mass of Hydrogen (H) = 1.008 g/mol
Atomic mass of Oxygen (O) = 15.999 g/mol

Calculation: For standard water (H₂O): (2 × 1.008) + 15.999 = 18.015 g/mol

3. Importance of Molar Mass

Details: Molar mass is essential for stoichiometric calculations, preparing solutions, and converting between moles and grams in chemical reactions.

4. Using the Calculator

Tips: Enter the number of hydrogen and oxygen atoms in your water molecule. The calculator will compute the molar mass based on standard atomic weights.

5. Frequently Asked Questions (FAQ)

Q1: Why is water's molar mass approximately 18 g/mol?
A: Water (H₂O) contains two hydrogen atoms (1.008 g/mol each) and one oxygen atom (15.999 g/mol), totaling about 18.015 g/mol.

Q2: Does this calculator work for heavy water (D₂O)?
A: No, deuterium (D) has a different atomic mass (2.014 g/mol). For D₂O, the molar mass would be higher (about 20.027 g/mol).

Q3: How precise are the atomic masses used?
A: The values are based on IUPAC standard atomic weights, which account for natural isotopic abundance.

Q4: Can I calculate molar mass for other molecules with this?
A: This calculator is specifically configured for water molecules. Other molecules would require different atomic mass values.

Q5: Why is knowing water's molar mass important?
A: It's essential for preparing molar solutions, calculating reaction yields, and understanding water's physical properties in chemistry.