CalculateY
Quick Answer
18.015 grams of water (molar mass 18.015 g/mol) equals exactly 1 mole. To convert 36.03 grams of water to moles, divide by the molar mass: 36.03 / 18.015 = 2.0 moles.
Mass to Moles
Moles to Mass
Find Molar Mass
Common Examples
| Input | Result |
|---|---|
| 36.03 g of H2O (molar mass 18.015 g/mol) | 2.0 moles |
| 58.44 g of NaCl (molar mass 58.44 g/mol) | 1.0 moles |
| 3 moles of CO2 (molar mass 44.01 g/mol) | 132.03 g |
| 100 g of a substance, 0.5 moles measured | Molar mass = 200 g/mol |
How It Works
All three conversions derive from the same fundamental relationship, known as the mole formula:
n = mass / M
Where:
- n = number of moles (mol)
- mass = mass of the substance (grams)
- M = molar mass of the substance (g/mol)
Rearranging this formula gives two additional forms:
mass = n x M (to find mass from moles)
M = mass / n (to find molar mass from mass and moles)
The molar mass (M) of a substance equals the sum of the atomic masses of all atoms in one molecule. For example, water (H2O) has a molar mass of (2 x 1.008) + 15.999 = 18.015 g/mol. You can look up atomic masses on the periodic table or use a molar mass calculator.
One mole always contains exactly 6.022 x 10^23 particles (Avogadro’s number), regardless of the substance.
Worked Example
To find the number of moles in 100 grams of calcium carbonate (CaCO3, molar mass = 100.09 g/mol): n = 100 / 100.09 = 0.999 mol, or approximately 1 mole. To find the mass of 2.5 moles of sodium chloride (NaCl, molar mass = 58.44 g/mol): mass = 2.5 x 58.44 = 146.1 g. To find the molar mass of a substance when 250 g produces 1.25 moles: M = 250 / 1.25 = 200 g/mol.