Mole Concept Quick Revision Sheets

Key Concepts

• Mole: A unit of measurement for the amount of a substance.
• Avogadro's Number: The number of atoms, molecules, or ions in one mole of a substance (approximately 6.022 x 10^23).
• Molar Mass: The mass of one mole of a substance, expressed in grams per mole (g/mol).
• Molar Volume: The volume occupied by one mole of a gas at standard temperature and pressure (STP), which is approximately 22.4 liters.

Formulas

• Number of moles:
  • Moles = Mass (g) / Molar Mass (g/mol)
  • Moles = Volume (L) / Molar Volume (L/mol)
• Mass from moles:
  • Mass (g) = Moles x Molar Mass (g/mol)
• Volume from moles (for gases at STP):
  • Volume (L) = Moles x Molar Volume (L/mol)

Calculations

Example 1: How many moles of water are in 18 grams of water?

• Molar mass of water = 18 g/mol
• Moles = 18 g / 18 g/mol = 1 mole

Example 2: What is the mass of 0.5 moles of carbon dioxide?

• Molar mass of carbon dioxide = 44 g/mol
• Mass = 0.5 moles x 44 g/mol = 22 grams

Additional Notes

• Empirical formula: The simplest whole-number ratio of atoms in a compound.
• Molecular formula: The actual number of atoms of each element in a molecule. 
  
• Percentage composition: The mass percentage of each element in a compound.
• Stoichiometry: The quantitative relationship between reactants and products in a chemical reaction.