Molar Mass and the Mole Concept
The mole is the fundamental unit for counting atoms and molecules in chemistry. One mole contains 6.022 × 10²³ particles (Avogadro's number). Molar mass (g/mol) is the mass of one mole of a substance, numerically equal to its atomic or molecular weight. The relationship n = m/M connects mass (grams), molar mass, and moles.
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Formula
Molar Mass Calculator
Calculate moles, mass, or molar mass of a substance using n = m/M.
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Worked Example
Given:
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FAQs
How do I find the molar mass of a compound?
Add the atomic masses of all atoms in the molecular formula. For H₂O: 2(1.008) + 16.00 = 18.016 g/mol. For NaCl: 22.99 + 35.45 = 58.44 g/mol. Atomic masses are found on the periodic table.
Why is the mole such an important concept in chemistry?
Chemical reactions occur between atoms and molecules in fixed ratios. The mole allows chemists to work with 'countable' quantities of atoms using measurable masses. Without the mole, calculating stoichiometry would require working with individual atoms — far too small to weigh directly.
What is Avogadro's number?
Avogadro's number (6.022 × 10²³) is the number of atoms, molecules, or particles in one mole of any substance. It was defined so that 12 g of carbon-12 contains exactly one mole of atoms. The number itself is extraordinarily large — it is approximately the number of sand grains needed to fill the Sahara Desert.