Moles from Grams Calculator
You can find this on the periodic table for specific elements.
Total Moles
How to Calculate Moles from Grams
Calculating moles from grams is a fundamental skill in chemistry known as stoichiometry. It allows scientists and students to bridge the gap between the weight of a substance and the number of atoms or molecules present in that sample.
The Mole Formula
To convert grams to moles, you use the following mathematical formula:
n = m / M
- n = Number of moles (mol)
- m = Mass of the substance in grams (g)
- M = Molar mass of the substance (g/mol)
Step-by-Step Calculation Guide
- Find the Mass: Weigh your sample in grams. If your weight is in kilograms or milligrams, convert it to grams first (1 kg = 1000 g).
- Determine the Molar Mass: Look at the periodic table for the atomic weight of the element. For compounds, add the atomic weights of all atoms in the chemical formula.
- Divide: Divide the mass of your substance by its molar mass to get the number of moles.
Practical Examples
Example 1: Water (H₂O)
Suppose you have 36 grams of water. The molar mass of water is approximately 18.015 g/mol.
Calculation: 36g ÷ 18.015 g/mol = 1.998 moles.
Example 2: Table Salt (NaCl)
Suppose you have 100 grams of table salt. The molar mass of NaCl is 58.44 g/mol.
Calculation: 100g ÷ 58.44 g/mol = 1.711 moles.
Common Molar Masses Reference
| Substance | Formula | Molar Mass (g/mol) |
|---|---|---|
| Carbon | C | 12.011 |
| Oxygen | O₂ | 31.998 |
| Glucose | C₆H₁₂O₆ | 180.16 |
| Iron | Fe | 55.845 |