quantitive chemistry

• atom - the smallest thing that everything is made of
• molecule - a group of two or more atoms held together by covalent bonds (must be non-metals)
• compound - two or more elements joined together by chemical bonds
• moles - the number of particles in a given amount of substance
• mass number = number of protons + number of neutrons in an atom of an element
• relative formula mass - the sum of the relative atomic masses of all the atoms in a formula
• % mass of an element in a compound

  ((relative atomic mass x number of atoms)/ relative formula mass) x 100
• percentage yield - actual yield/ theoretical yield x 100%
• conservation of mass - the mass that goes into a chemical reaction must be equal to the mass that comes out
• limiting reactant - the reactant which is completely used up first, so determines the maximum quantity of product formed
• moles = mass / relative formula mass
• mass = moles x relative formula mass
• how to estimate uncertainty?

  1. calculate the mean of the numbers
  2. find the range
  3. find the bounds the numbers are in
• mean = (x + y) / 2
• range = highest value - lowest value
• find the uncertainty of the following results:

  0.42

  0.37

  0.4

  0.38

  0.3

  0.374 ± 0.06
• what the reasons for not having a 100% yield?

  product can escape,

  reversible reaction,

  stuff you can't weigh (residue from previous reactions)
• concentration = mass of solute / volume of solvent
• $1dm^3$=$1000cm^3$