Quantitative chemistry

• The total mass of all substances is conserved in a chemical reaction
• The atoms that go in must come out, so we must balance equations
• Relative atomic mass


  The mass of an atom relative to the mass of a carbon-12 atom
• Relative formula mass


  The sum of the relative atomic masses of the atoms in a compound
• CO2 has a relative formula mass of 44 (12 + 2 x 16)
• Reactions that produce a gas product can result in a seeming decrease in mass of the reactants
• Mole


  A specific number of atoms or molecules, used to compare amounts of substances
• If you have as many grams of a substance as its relative atomic or formula mass, you have one mole
• Moles


  Calculated as g / relative atomic/formula mass
• Balancing a chemical equation

  Determine the number of moles of each reactant and product
• Calculating mass of product from mass of reactant

  Mass -> Moles -> Moles -> Mass
• One mole of any gas takes up 24 dm^3 at room temperature and pressure
• You can convert between moles and volume by multiplying/dividing by 24
• Concentration of a solution

  Can be expressed in g/dm^3 or mol/dm^3
• If 1 mol of HCl is dissolved in 1 dm^3 of water, the concentration is 1 mol/dm^3
• Atom economy


  Efficiency of a reaction in terms of the mass of desired product compared to total mass of reactants
• CO2 is an incredibly important gas necessary for life to thrive
• Atom economy for CO2 production is 55% (44 / 80 x 100)