Chemistry formulas

• Percentage by mass = mass of reactant / mass of product x 100
• Finding mass from percentage abundance of two isotopes = (mass * % abundance) + (mass * % abundance)
• To convert cm^3 to dm^3 divide by 1000
• concentration = mass / volume
• mean rate of reaction = quantity of reactant used or product formed / time taken
• moles = mass / Mr
• Concentration = mol/dm^3
• Percentage yield = actual yield / theoretical yield x 100%
• Atomic number = protons