Chapter 4

the average mass of naturally occurring atoms of an element on a scale where the 12C atom has a mass of exactly 12 units

the sum of the relative atomic masses

The unit representing the amount of ions, atoms or molecules in a substance

The number of atoms, molecules or ions in a mole of a given substance, 6.02 x 10^23

24 dm3 at room temperature and pressure

using molecular mass ATOMIC MASS IS ONE, THEREFORE 2H2O IS 2+16 NOT 4+16: • Add the total atomic masses of 2 substances • Find the mass ration by dividing one mass by the total (e.g magnesium = 24, Oxygen = 16, 24/30) • Divide the mass ratio by the atomic mass (e.g 60/24) • Put the ratio of the two elements in their simplest form. (e.g 2.5:2.5 = 1:1)

actual yield/ theoretical yield * 100 Find the theoretical yield by dividing the initial mass by the molecular mass and multiplying it by the molecular mass of the product. Find if the number of moles is proportional for the reactant as well as the product (e.g 2Ca and 2CaO have the same number of moles). Actual yield will be told.

calculate the molecular mass of the empirical formula, divide the molecular mass by the mass of the empirical formula, multiply the numbers in the empirical formula by this value.

mass of pure product/ mass of impure product * 100

Mass (g) / Volume solvent (dm^3)

Number of moles/ volume solvent (dm^3)

number of moles * avagadros constant

mass (g) / Molecular mass

Mass (kg) / density (kg/dm^3)

Volume (dm^3) / 24 (dm^3/mol)