Moles Calculator
Calculate the number of moles from mass and molar mass, or solve for mass, using moles equals mass divided by molar mass.
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Calculate the number of moles from mass and molar mass.
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Calculate the number of moles
The mole is the chemist's unit for counting particles, and the number of moles in a sample is found by dividing its mass by its molar mass, the mass of one mole of the substance. This calculator performs that division and also reports the actual number of particles using Avogadro's number, about six times ten to the twenty-three per mole. Eighteen grams of water, with a molar mass of about 18.015, is very close to one mole, containing roughly Avogadro's number of molecules.
The same relationship rearranges to find the mass of a given number of moles, by multiplying moles by molar mass.
Moles in chemistry
The mole concept is the bridge between the mass of a substance that you can weigh and the number of atoms or molecules it contains, which is what matters in chemical reactions. Balancing equations, calculating reaction yields, and preparing solutions of known concentration all depend on converting between mass and moles. Molar mass is read off the periodic table by summing the atomic masses of the atoms in a formula.
Avogadro's number is exact by modern definition, linking the mole to a fixed count of particles. Keep mass in grams and molar mass in grams per mole for a result in moles. All calculation happens locally in your browser.
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Frequently Asked Questions
What is the moles formula?
The number of moles equals the mass of the sample divided by its molar mass in grams per mole.
What is a mole?
It is the chemist\'s counting unit, representing Avogadro\'s number of particles, about six times ten to the twenty-three.
How do I find molar mass?
Sum the atomic masses of all the atoms in the chemical formula, read from the periodic table, in grams per mole.
Can I find mass from moles?
Yes. Rearranging, mass equals moles times molar mass, so you can solve for whichever quantity you need.
What is Avogadro\'s number?
It is the number of particles in one mole, now defined exactly as about 6.022 times ten to the twenty-three per mole.
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How to Use
Enter the mass and molar mass to find the number of moles.
Disclaimer: This tool is provided "as is" without warranty of any kind. Results are for educational and utility purposes.