The Mole: Counting by Weighing

Also called

mole · mole concept · Avogadro number · Avogadro constant · 6.022 x 10^23 · molar mass · gram atomic mass · gram molecular mass · molar volume · 22.4 litres at STP · 12 g of carbon · 18 g of water · counting by weighing · two-pan balance · मोल · आवोगाद्रो संख्या · मोलर द्रव्यमान

Topics

• One mole of any substance contains 6.022 × 10²³ particles: this number is the Avogadro constant.
• The mass of one mole in grams equals the atomic or molecular mass in u: 12 g of carbon-12 is one mole of atoms.
• 18 g of water (2 × 1 + 16 = 18 u) is one mole of water molecules: about 18 mL, a few spoonfuls.
• One mole of any gas fills 22.4 L at STP (0 °C and 1 atm): a cube about 28 cm along each side.
• A dozen is a count of 12; a mole is a count of 6.022 × 10²³. Chemists count atoms by weighing them.
• Equal numbers of particles can have different masses: a water molecule is 1.5 times as heavy as a carbon atom.
• Number of moles = mass given ÷ molar mass; number of particles = moles × 6.022 × 10²³.
• The mole links the invisible world of atoms to masses you can weigh on a balance.

About this model

A GLB file of about 377 KB, shown in Lably's 3D viewer and, on a phone, placed in your room with AR. Credit: Model, science and animation: Lably (built procedurally with three.js; no downloaded meshes). | CC BY 4.0. Original geometry and animation made for Lably.

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