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How to Calculate Molar Mass

What is Molar Mass?

Molar mass is the mass of one mole (6.022 × 10²³ particles) of a substance, expressed in grams per mole (g/mol). It equals the sum of the atomic masses of all atoms in the molecular formula. Molar mass is essential for stoichiometry — calculating how much of each substance reacts or is produced in a chemical reaction.

Formula

Molar mass = sum of (atomic mass × count) for each element

Step-by-Step Guide

  1. 1Molar mass = sum of (atomic mass × count) for each element
  2. 2Atomic masses are from the IUPAC periodic table (in amu = g/mol)
  3. 3H₂O: 2 × 1.008 + 16.00 = 18.016 g/mol
  4. 4Avogadro's number: 1 mole = 6.022 × 10²³ molecules
  5. 5n = m / M: moles = mass (g) / molar mass (g/mol)

Worked Examples

Input
H₂O (water)
Result
18.02 g/mol
2H(1.008) + O(15.999) = 18.015
Input
NaCl (table salt)
Result
58.44 g/mol
Na(22.99) + Cl(35.45) = 58.44
Input
C₆H₁₂O₆ (glucose)
Result
180.16 g/mol
6×12.011 + 12×1.008 + 6×15.999

Frequently Asked Questions

What is Molar Mass Calc?

Molar mass is the mass of one mole (6. 022 × 10²³ particles) of a substance, expressed in grams per mole (g/mol)

How accurate is the Molar Mass Calc calculator?

The calculator uses the standard published formula for molar mass calc. Results are accurate to the precision of the inputs you provide. For financial, medical, or legal decisions, always verify with a qualified professional.

What units does the Molar Mass Calc calculator use?

This calculator works with inches. You can enter values in the units shown — the calculator handles all conversions internally.

What formula does the Molar Mass Calc calculator use?

The core formula is: Molar mass = sum of (atomic mass × count) for each element. Each step in the calculation is shown so you can verify the result manually.

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