CalKit

Molar Mass Calculator

Calculate molar mass.

화합물 프리셋
총 몰 질량
18.015g/mol

원소별 기여

H × 22.016 g/mol
O × 115.999 g/mol

Overview

Calculate molar mass (molecular weight) by summing the atomic masses of elements in a chemical formula. Essential for stoichiometry, solution concentration calculations, and laboratory reagent preparation.

Formula

Molar Mass = Σ(Atomic Mass × Number of Atoms)

Examples:
  H₂O: (1.008 × 2) + (16.00 × 1) = 18.015 g/mol
  NaCl: 22.99 + 35.45 = 58.44 g/mol
  C₆H₁₂O₆ (glucose): (12.01 × 6) + (1.008 × 12) + (16.00 × 6) = 180.16 g/mol

Moles = Mass (g) ÷ Molar Mass (g/mol)

How to Use

  1. 1Enter the chemical formula (e.g., H2O, NaCl, C6H12O6).
  2. 2Each element's atomic mass and count are displayed.
  3. 3The total molar mass (g/mol) is calculated automatically.
  4. 4Optionally enter mass to find the number of moles.

Tips

  • ✔Key atomic masses: H(1.008), C(12.01), N(14.01), O(16.00), S(32.07), Cl(35.45).
  • ✔For ionic compounds, it is the formula unit mass.
  • ✔For hydrates, include the water of crystallization (e.g., CuSO₄·5H₂O).
  • ✔Avogadro's number: 1 mol = 6.022 × 10²³ particles.

FAQ

Q. What is the difference between molar mass and molecular weight?

Molar mass is the mass of 1 mole (g/mol), while molecular weight expresses a single molecule's mass in atomic mass units (amu or Da). They have the same numerical value but different units (e.g., H₂O: 18.015 g/mol vs. 18.015 amu).

Q. What is a mole (mol)?

A mole is the SI unit for amount of substance, containing Avogadro's number (6.022 × 10²³) of particles (atoms, molecules, ions, etc.). It is defined by the number of atoms in 12 g of Carbon-12.

Q. How is molar mass used in concentration calculations?

Molarity (M) = moles of solute ÷ volume of solution (L). Moles = mass (g) ÷ molar mass (g/mol). For example, dissolving 58.44 g NaCl in 1 L gives a 1 M NaCl solution.

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