Mole Calculator (n = m/M)
Calculate the number of moles from mass and molar mass
Number of Moles (n):
0.00 mol
Please enter valid positive numbers for both fields.
Understanding the Mole Calculation Formula
In chemistry, the mole is the standard unit used to measure the amount of a substance. One mole contains exactly 6.02214076 × 1023 elementary entities (Avogadro's number).
To find the number of moles in a specific sample, we use the fundamental chemical equation:
n = m / M
- n = Number of moles (mol)
- m = Mass of the substance in grams (g)
- M = Molar mass of the substance (g/mol)
Example: How to Calculate Moles for Water
Suppose you have 36 grams of pure water (H2O). How many moles is that?
- Identify the Mass (m): 36g.
- Identify the Molar Mass (M): For water, it is approximately 18.015 g/mol (2 × 1.008 for Hydrogen + 15.999 for Oxygen).
- Apply the formula: n = 36 / 18.015
- Result: n ≈ 1.998 moles.
Why is this important?
Converting grams to moles is the first step in stoichiometry. It allows chemists to predict the amounts of products that will form in a chemical reaction based on the law of conservation of mass. Without knowing the molar amount, it is impossible to balance chemical equations accurately.
Common Molar Masses:
| Substance | Molar Mass (g/mol) |
|---|---|
| Carbon Dioxide (CO2) | 44.01 |
| Sodium Chloride (NaCl) | 58.44 |
| Glucose (C6H12O6) | 180.16 |