What is a Mole?

Chapter 9

What is a mole?

• A mole is used to count very small atoms, molecules, ions, and formula units (Particles)
• The mole represents a large number of extremely small particles
• 1 mole = Avogadro’s number of particles
• Avogadro’s number is 6.02 x 10^23
• I mole = 6.02 x 10^23
• Individuals
• Atoms
• Molecules
• Ions
• Formula units

Why is the number special?

• The mole is the number of atoms in 12C in exactly 12.000 g of pure 12 C
• So there is exactly one mole of atoms in the atomic mass of an element when that mass is expressed in grams
• 1 mole = the atomic mass of an element expressed in grams

What is the mass of one mole?

• 1 mole of Carbon has a mass of 12.011 grams
• 6.02 x 10^23 atoms of Carbon has the mass of 12.011 g
• The mass of half of a mole of Carbon is 6.0055 g
• 12.011 g of Carbon contains the same number of atoms as one mole of carbon - 6.02 x10^23

Copper

• 1 mole of Copper has a mass 63.546 grams
• 6.02 x 10^23 atoms of copper has the mass of 63.546 g
• The mass of half a mole of copper is equal to 31.773 g
• 63.546 g of Cu contains the same number of one mole of Carbon