Mole Calculator

Mass route: n = m / M

Particles route: n = N / N_A

Solution route: n = M · V

Gas route: n = PV / RT

Example Problems

Mass route: 5.00 g NaCl (M=58.44 g·mol⁻¹) → 0.0856 mol

Particles route: 2.50×10²³ / 6.022×10²³ = 0.415 mol

Gas route: (1×2)/(0.0821×298)=0.0818 mol

What is a mole in chemistry?
A mole (mol) is 6.022×10²³ particles (Avogadro’s number). It links the microscopic particle count to measurable amounts in the lab.

How do I calculate moles from mass?
Use n = m/M, where m is the sample mass (g) and M is the molar mass (g·mol⁻¹). Example: 10.0 g NaCl ÷ 58.44 g·mol⁻¹ = 0.171 mol.

How do I calculate moles from number of particles?
Use n = N/NA, where N is the number of particles and NA = 6.022×10²³ mol⁻¹.

How do I calculate moles from solution data (molarity and volume)?
Use n = M·V, where M is molarity (mol·L⁻¹) and V is volume in liters. Example: 0.200 L of 0.500 M solution → 0.100 mol.

How do I calculate moles from gas data?
Use the ideal gas law n = PV/(RT). Convert T to K and match R’s units (e.g., 0.0821 L·atm·mol⁻¹·K⁻¹).

What is Avogadro’s number?
Avogadro’s number NA = 6.022×10²³ mol⁻¹, representing the number of particles in one mole.

What units should I use?
Use grams / g·mol⁻¹ for mass / M, liters for volume, Kelvin for temperature, and consistent pressure units with R.

What are common mistakes when computing moles?
1️⃣ Forgetting to convert °C → K · 2️⃣ Mixing mL/L · 3️⃣ Wrong R units · 4️⃣ Formula mass errors · 5️⃣ Early rounding.