Quantitative Chemistry

• The Law of Conservation of Mass

  no atoms are lost or made during a chemical reaction so the mass of the products equals the mass of the reactants
• The relative formula mass (Mr ) of a compound

  the sum of the relative atomic masses of the atoms in the numbers shown in the formula
• Percentage by mass in a compound

  % mass of an element in a compound =

  (Ar x number of atoms of element/Mr of compound) x 100
• What are chemical amounts measured in?

  Moles - mol
• What is the mass of one mole of a substance (g) numerically equal to?

  it's relative formula mass
• What is one mole of any substance?

  an amount of the substance that contains an Avogadro number of particles
• What is the value of Avogadro's Constant?

  6.02x10^23
• What can the masses of reactants and products be calculated from?

  balanced symbol equations
• Number of moles calculation

  number of moles = mass (g)/molar mass(Mr)