5 the mole and avogadro constant

• One mole of anything contains 6.022×10²³ of those things. One mole of bananas is 6.022×10²³ bananas. One mole of water molecules is 6.022×10²³ water molecules
• 6.022×10²³ is known as the avogadro constant (=6.022×10²³mol-1)
• The avogadro number was chosen so that the mass of one mole of particles of a substance equals the Mr in grams. For example, the Mr of water is 18.0 and the mass of one mole of water molecules in 18.0 grams
• Moles = mass(g) ÷ Mr
• Mass = moles × Mr
• Mr = moles ÷ mass (g)
• 1 ton = 1,000,000g
• 1 kg = 1,000 grams
• 1mg = 0.001 grams