Nov.17--The Mole

Equal volumes of different gases at the same temperature and pressure have the same number of particles.

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Avogadro’s Hypothesis: If they have the same number of particles, the mass ratio is due to the mass of the particles.

Atomic Mass: mass of one atom of the element in atomic mass units

Ex. Fluorine = 19.0 amu

Formula Mass: mass of all the atoms of a formula of an ionic compound (in amu)

Ex. Potassium Fluorine = K (39.1) + F (19.0) = 58.1 amu

Molecular Mass: mass of all the atoms of a formula of a covalent compound (in amu)

Ex. Carbon Dioxide = C (12.0) + O₂ (16.0×2) = 44.0 amu

   express in grams per mole: 44.0 g/mol

1 mole of oxygen = 16.0 g/mol

1 mole of carbon = 12.0 g/mol

• They have the same number of particles!
 

 

Youtube Video: introduction to the idea of a mole as a number
http://www.youtube.com/watch?v=AsqEkF7hcII 

Avogadro’s Number: The number of particles in 1 mole of any amount of substance is:

  particles/mol