Mole Calculator
Convert between moles, mass, and number of particles using molar mass.
Moles
Calculation Steps
Derived Values
What is a Mole?
The mole (mol) is the SI base unit for the amount of a substance. One mole contains exactly Avogadro's number of elementary entities — atoms, molecules, ions, or other particles. This number provides a bridge between the atomic scale and quantities we can measure in the laboratory.
Avogadro's Number:
N_A = 6.02214076 × 10²³ particles/mol
One mole of any substance contains 6.02214076 × 10²³ particles. For example, one mole of water contains that many water molecules.
Mole–Mass–Particle Relationships
The mole connects mass, amount of substance, and the number of particles through molar mass and Avogadro's number:
- moles = mass / molar mass
- mass = moles × molar mass
- particles = moles × N_A
- moles = particles / N_A
- • moles = amount of substance (mol)
- • mass = mass of substance (g)
- • molar mass = mass per mole (g/mol)
- • N_A = Avogadro's number (6.02214076 × 10²³)
Worked Example
Example: Moles and Molecules of Water
Problem: How many moles and how many molecules are in 18 g of water (molar mass = 18 g/mol)?
Step 1: Calculate moles
n = mass / molar mass = 18 g / 18 g/mol = 1 mol
Step 2: Calculate number of molecules
N = moles × N_A = 1 mol × 6.02214076 × 10²³ = 6.022 × 10²³ molecules
Answer: 1 mole = 6.022 × 10²³ water molecules
Note: This calculator uses the exact value of Avogadro's number (6.02214076 × 10²³). Results depend on the accuracy of the molar mass you provide. Always verify molar masses from reliable sources such as NIST or a periodic table.