Amount of Subtance

• number of particles = number of moles x Avogadro's constant
• 1 mole is the number of atoms in 12g of Carbon-12 (6.022*10^23)
• The ideal gas equation lets you find the number of moles in a certain volume at any temperature and pressure:

  pV=nRT

  p= pressure in Pa

  V= volume in m^3

  n= moles

  R= gas constant

  T= temp in K
• Neutralisation reaction- an acid reacts with an alkali to form a salt and water
• Titrations involve neutralisation reactions to work out the concentration of an acidic or alkaline solution
• Empirical formula- the smallest whole number ratio of atoms of each element present in a compound
• Molecular formula- the actual numbers of atoms in a molecule
• When a solution is diluted, the concentration and volume change but the total number of moles stays the same.

  When an aliquot (portion) is taken, the concentration remains the same, but the volume and number of moles are different
• The theoretical yield- the maximum amount of product that can be made from a given amount of reactants
• At standard conditions, 1 mol of any gas occupies the volume:

  n=v/24
• Percentage yield- how much product is made compared to theoretical yield

  % yield = (actual yield / theoretical yield) x 100

  Never 100% yield because:

  • loss of product in transfer
  • side reactions/ byproducts
  • reversible reactions
  • incomplete reactions
• Atom economy- compares the amount of desired product with all products made

  Atom economy = (mass or Mr of desired product / total mass or Mr of all products) x 100

  Can be 100% when there is only 1 product
• Limiting reactant- the reactant that is used up in a chemical reaction since it limited the amount of products formed
• Relative atomic mass- the average mass of one atom of an element relative to 1/12 the mass of one atom of Carbon-12
• Relative molecular mass0 the average mass of one molecule of an element/compound relative to 1/12 the mass of one atom of carbon-12