Moles and masses - Higher

• What is the unit for the amount of substance?

  The mole
• How can the number of particles in a substance be found?

  Using the Avogadro constant
• What does the mass of a product depend on?

  The mass of the limiting reactant
• What is the relative formula mass?

  • The sum of the relative atomic masses of the atoms in a chemical formula.
• How do you calculate the mass of a substance from moles?

  Mass = relative formula mass × amount
• What is the mass of 0.25 mol of carbon dioxide if the relative formula mass (M_r) of CO₂ is 44?


  11 g
• Calculate the mass of 0.10 mol of iron if the atomic mass (A_r) of Fe is 56.

  1. 6 g
• What is the calculation method for substances that are metals or exist as separate atoms?

  Use A_r instead of M_r
• How do you calculate the amount of a substance in moles from its mass?

  Amount = \(\frac{mass}{relative~atomic~or~formula~mass}\)
• Calculate the amount of carbon atoms in 6.0 g of carbon if the atomic mass (A_r) of C is 12.

  0.5 mol
• What is the amount of water molecules in 36 g of water if the relative formula mass (M_r) of water is 18?

  1. 0 mol
• What are the key steps in mole calculations?

  1. Identify the mass of the substance.
  2. Determine the relative atomic or formula mass.
  3. Use the formula: \(amount=\frac{mass}{relative~atomic~or~formula~mass}\).