Mole Calculator
Calculate mole with our free science calculator. Uses standard scientific formulas with unit conversions and explanations.
Formula
Moles = Mass (g) / Molar Mass (g/mol)
The number of moles equals the mass of a substance divided by its molar mass. The number of particles equals moles multiplied by Avogadro's number (6.022 x 10^23). For gases at STP, the volume in liters equals moles multiplied by 22.414 L/mol.
Worked Examples
Example 1: Mass of Water to Moles
Problem: How many moles are in 36 grams of water (H2O, molar mass 18.015 g/mol)?
Solution: Moles = mass / molar mass\nMoles = 36 / 18.015 = 1.999 mol\nParticles = 1.999 x 6.022 x 10^23 = 1.2038 x 10^24\nVolume at STP = 1.999 x 22.414 = 44.80 L
Result: 1.999 moles of water
Example 2: Moles of CO2
Problem: Calculate moles in 100 grams of carbon dioxide (CO2, molar mass 44.01 g/mol).
Solution: Moles = 100 / 44.01 = 2.272 mol\nParticles = 2.272 x 6.022 x 10^23 = 1.369 x 10^24\nVolume at STP = 2.272 x 22.414 = 50.93 L
Result: 2.272 moles of CO2
Frequently Asked Questions
What is a mole in chemistry?
A mole is a fundamental unit in chemistry that represents exactly 6.02214076 x 10^23 particles (atoms, molecules, ions, or other entities). This number is known as Avogadro's number. One mole of any substance contains the same number of particles, just as one dozen always means twelve items. The mole bridges the gap between the atomic scale and the laboratory scale, allowing chemists to count atoms by weighing substances. For example, one mole of water (H2O) has a mass of about 18.015 grams.
How many atoms are in one mole?
One mole contains exactly 6.02214076 x 10^23 particles, a value known as Avogadro's number or Avogadro's constant. This enormous number was chosen so that one mole of carbon-12 atoms has a mass of exactly 12 grams, linking the atomic mass unit to grams. To put this number in perspective, if you had a mole of sand grains, they would cover the entire surface of the Earth to a depth of several kilometers. Despite its size, Avogadro's number is a precisely defined constant in the SI system since 2019.
What is a mole and why is it used in chemistry?
A mole is 6.022 x 10^23 particles (Avogadro's number). It allows chemists to count atoms and molecules by weighing them. One mole of any element weighs its atomic mass in grams. For example, one mole of carbon weighs 12 grams and contains 6.022 x 10^23 carbon atoms.
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Enter values as precisely as possible using the correct units for each field. Check that you have selected the right unit (e.g. kilograms vs pounds, meters vs feet) before calculating. Rounding inputs early can reduce output precision.
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