chemistry paper 2

• FLAME TESTS- potassium

  lilac
• FLAME TESTS- sodium

  yellow
• FLAME TESTS- calcium

  orange/red
• FLAME TESTS- copper

  green
• METAL HYDROXIDE- copper II

  blue precipitate
• METAL HYDROXIDE- iron II

  green precipitate
• METAL HYDROXIDE- iron III

  brown precipitate
• HALIDE TESTS- bromide

  cream precipitate
• HALIDE TESTS- chloride

  white precipitate
• HALIDE TESTS- iodine

  yellow precipitate
• FLAME TESTS- lithium

  crimson
• test for hydrogen

  squeaky pop
• test for carbon dioxide

  bubble the gas through lime water
• results of carbon dioxide test

  water will go cloudy
• test for cholrine


  damp litmus paper
• result of chlorine

  the paper will go white
• what is potable water


  water that is safe to drink
• What are the three criteria for water to be considered potable? 

  Levels of dissolved substances must be fairly low

  The pH must be between 6.5 and 8.5

  The must be no microorganisms
• where does the uk get most of its potable water from

  fresh water sources
• what are the fresh water sources

  rivers

  lakes

  Aquifers
• why is fresh water good

  it is replaced quickly

  it is easy to acsess
• Three stages of treating fresh water

  1. First, pass the water through a wire mesh. This will filter out any large objects like plastic bottles or leaves.
  2. Second, pass the water through a bed of sand and gravel. This will filter out smaller things like bits of rock.
  3. Lastly, sterilise the water to kill any microorganisms. There are three different ways to do this: 1)bubbling chlorine gas through it, 2) exposing it to ozone, 3) exposing it to ultraviolet radiation. 
• what is desalination


  the extraction of potable water from sea water
• what is a disadvantage of desalination

  it requires lots of energy which makes it expensive

  it causes global warming
• what are the 2 techniques used in desalination


  reverse osmosis

  simple distillation
• what are the factors which effect rates of chemical reactions

  concentration

  pressure

  surface area

  temp

  catalysts
• collision theory


  reactions can occur when particles collide with each other with sufficient energy
• activation energy


  the minimum amount of energy that the particles must have to react
• what happens when you increase the temp

  it increases the frequency of collisions which increases the rate of reaction
• what happens if you increase the concentration of a solution

  the pressure of gases increases the frequency of collisions and increases the rate of reaction
• what do catalysts do


  speed up chemical reactions without being used or changed during the reaction
• catalysts can decrease the activation energy which ...


  increases the proportion of particles with energy react
• catalysts provide a different pathway for a chemical reaction that has a lower activation energy
• what is a reversible reaction


  products of the reaction can react to produce the original reactants
• in a reversible reaction one way is endothermic and the other way is exothermic
• in a reversible reaction the same amount of energy is transferred both ways
• in a reversible reaction equilibrium is reached when the reactions occur at the same rate in the same direction
• how does a change in conditions effect equilibrium

  the system responds to counteract the change

  the system would be imbalanced so would not be at eqilibrium
• how does a change in concentration effect equilibrium

  when the concentration of reactants is increased, the position of equilibrium shifts towards the products so produced more products until equilibrium is reached

  when the concentration of products is increased equilibrium shifts towards the reactants so more reactants is produced
• how does a change in temperature effect equilibrium

  increase= equilibrium moves in the direction of the endothermic reaction

  decrease= equilibrium moves in the direction in the exothermic reaction