V Chemistry - Moles

Formula for Mass Calculations

n = m(g) / Mr

Formula for Volume Calculations

n = v(dm³) / Vm(24dm³)

Formula for Concentration Calculations

n = c(mol/dm³) x v(dm³)

Steps for finding: Mass, Volume or Concentration

Find:

• Number

• Ratio

• Amount

Empirical Formula

Simplest whole number ratio of atoms of each element in a compound

Molecular Formula

Actual number of atoms of each element in one molecule of substance

Steps for finding: Empirical Formula

Find:

• Mass of each element

• Mr of each element

• Number of moles of each element, ratio

Steps for finding: Molecular Formula

Find:

• Empirical formula

• Mr of combined compound,

• Divide the mass by the combined Mr

• Add number found after each element

Steps for finding: x (in hydrated salt calculations)

Find:

• Number of moles of each element,

• Number of moles of water lost

• The molar ratio of: element : H2O in the form: 1 : x, first to 3sf then to the nearest whole number

Steps for finding the formula after: Combustion and Reduction

• Determine the mass of each element

• Find the empirical formula