Grams to Moles Calculator
Mass & Molar Conversion
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Moles
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What is a "Mole"? (Not the animal)
In chemistry, atoms are too small to count individually. Even a single drop of water contains trillions of atoms. To make the math manageable, chemists count atoms in groups called Moles.
Think of it like a "Dozen."
- 1 Dozen = 12 items.
- 1 Mole = 6.022 × 10²³ items.
This huge number is called Avogadro's Constant. It allows us to translate the atomic world (atoms) into the human world (grams).
The Formula
To convert between the weight of a substance and the number of moles, we use this simple triangle:
Moles (n) = Mass (m) ÷ Molar Mass (M)
- m (Mass): The weight you measure on a scale (in Grams).
- M (Molar Mass): The weight of 1 mole of that substance (g/mol). You find this on the Periodic Table.
- n (Moles): The quantity of the substance.
Real World Example: Water (H₂O)
Imagine you have a glass with 54 grams of water. How many moles is that?
- Find Molar Mass: Hydrogen is 1.01 g/mol. Oxygen is 16.00 g/mol.
(2 × 1.01) + 16.00 = 18.02 g/mol. - Divide: 54g ÷ 18.02 g/mol = 2.997 Moles.
- Result: You have roughly 3 moles of water.
Why Do Chemists Use Moles?
Chemical reactions happen atom-for-atom, not gram-for-gram.
The Reaction Problem:
To make water (H₂O), you need 2 Hydrogen atoms for every 1 Oxygen atom.
However, Oxygen is 16x heavier than Hydrogen.
If you mixed 1g of Hydrogen with 1g of Oxygen, you would have way too much Hydrogen left over because the Oxygen atoms are so heavy and few.
By using Moles, chemists can mix the exact ratio of particles needed for the reaction.
To make water (H₂O), you need 2 Hydrogen atoms for every 1 Oxygen atom.
However, Oxygen is 16x heavier than Hydrogen.
If you mixed 1g of Hydrogen with 1g of Oxygen, you would have way too much Hydrogen left over because the Oxygen atoms are so heavy and few.
By using Moles, chemists can mix the exact ratio of particles needed for the reaction.
Common Molar Masses
| Substance | Formula | Molar Mass (g/mol) |
|---|---|---|
| Hydrogen | H | 1.008 |
| Carbon | C | 12.011 |
| Oxygen | O | 15.999 |
| Water | H₂O | 18.015 |
| Table Salt | NaCl | 58.44 |
| Glucose | C₆H₁₂O₆ | 180.156 |