Calculations in chemistry

• The mole is the unit for amount of substance, with the number of particles in a substance found using the Avogadro constant.
• The mass of product depends upon the mass of limiting reactant.
• Mole calculations in chemistry involve finding the number of moles in a given mass, and vice versa.
• Reactions and moles in chemistry involve calculating the concentration of a substance in a reaction.
• Calculating concentrations in chemistry involves finding the volume of a substance in a reaction.
• Substance Formula: Ca, relative formula mass: 40, mass of 1 mol: 40 g.
• Substance Oxygen Formula: O 2, relative formula mass: 2 × 16 = 32, mass of 1 mol: 32 g.
• Substance Calcium carbonate Formula: CaCO 3, relative formula mass: 40 + 12 + (3 × 16) = 100, mass of 1 mol: 100 g.
• Avogadro constant: One mole of a substance contains the same number of particles as one mole of any other substance.
• Avogadro constant: The number of particles in one mole of particles is 6.02 × 10^23 per mole, which is 602,000,000,000,000,000,000 per mole.
• The amount in moles can apply to atoms, molecules, ions and electrons.
• One mole, 1 mol, of a substance is the Avogadro constant number (6.02 × 10^23) of particles (atoms, molecules, ions or formulae) of that substance.
• The number of particles in a substance can be calculated using: the Avogadro constant (6.02 × 10^23) and the amount of substance in mol.
• Number of water molecules = Avogadro constant x amount of substance in mol = 6.02 × 10^23 × 0.5 = 3.01 × 10^23.
• Number of atoms in 0.5 mol of oxygen molecules, O 2 = 6.02 × 10^23 per mol × 0.5 mol × 2 = 6.02 × 10^23.