A mole is simply a count: a fixed, huge number of particles. Holding the amount, the particle number and the mass apart, and linking them with the Avogadro constant, sets up everything that follows.
Amount of substance, in moles, is an SI base quantity. One mole contains the Avogadro number of particles, N₊ = 6.02 × 10²³, so the number of particles is N = nN₊.
Atoms and molecules come in numbers far too large to count one by one, so we group them: one mole is a fixed, enormous number of particles, the Avogadro number. Set an amount in the simulation and read off both the particle count and the mass.
Amount of substance is an SI base quantity, with the mole as its unit. The Avogadro constant N₊ = 6.02 × 10²³ mol⁻¹ converts amount to a number of particles: N = nN₊. The mass of the sample is the amount times the molar mass, m = nM, so two gases with the same amount have the same number of molecules but generally different masses.
Four quick checks on the mole and the Avogadro constant. Each correct answer earns XP and lights this skill on your star map.
Amount of substance is an SI base quantity whose unit is the:
The Avogadro constant N₊ is approximately:
The number of molecules in 3.0 mol of a gas is:
A 1.0 mol sample of helium and a 1.0 mol sample of oxygen have:
Amount of substance (mol) is a base quantity in its own right, separate from mass. Equal numbers of moles mean equal numbers of particles for any substance, but not equal masses: use N = nN₊ for the count and m = nM for the mass, where M is the molar mass.
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