Topic 8

• what is the purity


  When only one element or compound is present
• How the BP or MP effects purity

  - if the BP is a specific temperature the substance is pure.

  - if it has a range of BP/MP's the substance is impure
• What are formulations


  Useful mixtures with a precise purpose that are made by following a 'formula' (a recipe),
• Examples of formulations


  fuels,

  cleaning agents,

  paints,

  medicines,

  alloys,

  fertilisers,

  foods.
• Why are formulations important in the pharmaceutical industry?

  they are important as by altering the formulation of a pill chemists can ensure it delivers the drug to the correct part of the body at the right concentration, that it's consumable and has a long enough shelf life.
• Chromotography practical


  1) draw a line 2 cm from the bottom of a sheet of filter paper (use a pencil as insoluble). Mark 5 pencil spots at equal intervals along the line. Label each spot with a b c d and unknown.

  2) add a spot of the different inks to each ink using a glass capillary tube. place the sheet in a beaker or solvent e.g. water

  3) make sure the ink is not touching the solvent as the sides of the paper do not touch the beaker

  4) the solvent will seep up the paper carrying the ink with it

  5) once the ink has travelled at leas 3/4 way up the paper remove it a draw another pencil line on the du part of the paper as close to the wet edge as possible.

  6) leave to dry then measure the distance in me between the pencil lines. This is the distance travelled by solvents. Record this in your table.

  7) from each of the spots measure the distance in mm from the bottom line to the centre of each spot and record.

  8) use the Rf equation to calculate the Rf value of each colour.

  9) match the unknown to the information of A-D.
• What if the Rf calculation

  distance travelled by substance

  ------------------------------------

  distance travelled by solvent
• Test for Chlorine


  - litmus paper

  - bleaches it
• Test for Oxygen


  - glowing splint

  - relights it
• Test for Carbon Dioxide

  - Limewater

  - turns cloudy
• test for Hydrogen


  - lit splint

  - squeaky pop
• Test for carbonates


  - Add dilute acid to solution

  - connect the test tube to limewater

  - If Carbon dioxide gas produced, turns limewater milky (cloudy).
• Test for sulfates


  -add hydrochloric acid

  -add barium chloride

  - if there is sulfates a white precipitate forms (barium sulfate)
• Test for Halides


  Add dilute nitric acid and then silver nitrate solution
• Positive test for halides

  Chloride = white precipitate

  Bromide = cream precipitate

  Iodide = yellow precipitate
• Test for Cations


  Flame test
• Positive flame test for Lithium

  Crimson flame
• positive flame test for sodium

  Yellow flame
• Positive flame test for potassium


  Lilac flame
• Positive flame test for Calcium

  Orange-red flame
• positive flame test for copper


  Green flame
• Some metals form a precipitate with NaOH


  many metal hydroxides are insoluble and form a precipitate.
• Calcium precipitate colour


  white
• Copper II precipitate colour

  Blue
• Iron II precipitate colour

  Green
• Iron III precipitate colour


  brown
• Aluminium precipitate colour


  White - but redissolves if excess NaOH is added
• Magnesium precipitate colour


  White
• flame emission Spectroscopy

  
• Flame emission spectroscopy


  A method of instrumental (use of machine) analysis that records the colour of light given out by a substance when it is burned.
• Pros of using machines

  - very sensitive

  - very fast

  - very accurate