practicals.

• chromatography?

  1. draw baseline in pencil
  2. add spot of ink
  3. add paper into solvent make sure it is submerged but baseline doesnt touch water
  4. place lid to prevent solvent evaporating
  5. solvent seeps and carries ink and will seperate at different distances
  6. dry
• evaporation?

  1. pour solution into evaporating dish
  2. slowly heat solution with bunsen burner
  3. solvent starts ti evaporate and the solution becomes more concentrated
  4. keep heating until dry crystals are left
• crystallisation? ( used when solution decomposes when heated)

  1. pour solution into evaporating dish and gently heat solution
  2. some solvent will evaporate and solutionn will concentrate
  3. once crystals begin to form remove and leave to cool
  4. should start to form crystals as it becomes insoluable in cold highly conc. solution
  5. filter and dry using drying oven or desicator
• filtration and crystallisation used for rock salt?

  1. grind with pestle and mortar so it easily dissolves
  2. put into water and stir, salt dissolves sand wont
  3. filter and evaporate
• simple distillation for solutions?

  1. heat solution, lowest bp evaporates first
  2. vapour is cooled condensed and collected
  3. rest of solution is left behind in the flask
  4. csn only be used for very different bp, if temp goes higher than the highest bp theyll mix again
• fractional distillation for a mixture of liquids?

  1. (eg using crude oil) put mixture in flask with fractioning column then heat
  2. lowest bp evaporates firdt when temp on thermometer matches bp it will go to top of the column
  3. liquids with higher bps might evaporate but the column is cooler at the topso condense back down
• titrations?

  1. use pippette and pipette filler to add a set vollume of alkali to a conical flask, add 2 to 3 drops of phenolpthalein indicator too
  2. use a funnel to fill burette with acid of a known concentration BELOW EYE LEVEL WITH SAFETY GLASSES
  3. record initial volume of acid in the burette
  4. using burette add acid to alkali slowly by swirling until you nearly reach end point
  5. record final volume of acid in burette to see how much acid was needed to neutralise alkali
  6. ROUGH TITRATION for an approximate idea of endpoint
  7. SEVERAL READINGS
  8. MEAN no anomalous though
• energy transfer via chemical reaction?

  1. polystyrene cup , measure initial temp of reagants mix in the cup measure temp of solution
  2. add cotton insulation and a lid to prevent evaporation
• magnesium ribbon + HCI to produce hydrogen gas?

  1. add set volume of dilute HCI to conical flask and place onzerod mass balance
  2. add some mg ribbon to acid and quickly plug with cotton wool
  3. start stopwatch and record mass on balance at regular intervals
  4. plot on a graph time x loss of mass
  5. repeat with more conc. solutions
• sodium thiosulfate + HCI to produce a cloudy precipitate?

  (both clear solutions that react together to form a yellow precipitate of sulfur)

  1. add a set volume of dilute sodium thiosulfate to a conical flask
  2. place flask on piece of paper with black cross and add dilute HCI, start stopwatch
  3. watch black cross disspear through cloudy sulfur
  4. repeat with different conc.
• test for chlorine gas?


  chlorine bleaches damp litmus paper turning it white though it may turn red for a moment since chlorine is acidic
• test for oxygen?


  relights a glowing splint in presence of oxygen
• test for carbon dioxide?


  bubbling CO2 or shaking it through an aqueous solution of calcium hydroxide (limewater) causes a cloudy
• test for hydrogen?


  hold lit splint at the end of test tube containng hydrogen you will get a sqeuaky pop as hydrogen reacts with oxyge to make water
• HCI test for carbonates?


  put a sample in a test tube and use dropping pippette to add dilute HCI connected to tube of limewater, if carbonate present CO2 will be released and limewater will turn cloudy when it bubbles
• test for sulfates with HCI and barium chloride?


  use dropping pipette to add dilute HCI followed by a few drops of barium solution if sulfate ions present a white precipitate of barium sulfate will form
• test for halides with nitric acid and silver nitrate?


  add a few drops of dilute nitric acid followed by drops of silver nitrate solution

  CHLORIDE- white precip.

  BROMIDE - cream precip.

  IODIDE- yellow precip.
• flame test to identify metal ions?


  LITHIUM- crimson red

  SODIUM - yellow

  POTASSIU - lilac

  CALCIUM - orangey red

  COPPER - green
• test for metal hydroxides characteristic colour?

  add sodium hydroxidde to solution

  CALCIUM - white

  COPPER - blue

  IRON II - green

  IRON III - brown

  ALUMINIUM- white but then redissolves in excess NaOh to be colourless

  MAGNESIUM- white
• rusting?


  iron ail in boiling water wont rust as it removes oxygen and oil stops ait gegtting in but an iron nail in justair wont rust , both air and water will rust
• bioleaching?


  bactria used to convertcopper compounds in the ore into soluable copper compounds seperating the ore, the leachate contains copper ions which can be extracted via electrolysis/displacement
• phytominig?


  growing plants in copper soil as plants cant use or get rid of copper so it builds up . plant can be harvested dried and burned in a furnace and the ash can be extracted
• getting raw materials?


  extracted and processed needing energy causing pollution
• Manufacutirng?


  pollution and waste products , some can be turned into useful chemicals
• usage?


  greenhouse gases, fertilisers can leach into bodies of water and damage ecossystens , less waste for a longer period of time
• product disposal?


  landfill sites , uses eneergy to transport waste to landfill
• desalination?

  • test pH of water with ph meter not indiciator to prevent contamination, neutralise if not right via titration
  • test presence of sodium chloride for flame test and silvevr nitrate +nitric acid test
  • pour into distillation apparatus and heat to evaporate and conddense back to be collected
  • retest distilled water to check impurities removed and retesst pH.
  • can use reverse osmosis due to membrane filtration
• sewage treatment?

  • screening which is removing large pieces of grit
  • stands in settlement tank to undergo sedimentation - solids sink to produce sludge and effluent floats to top
  • effluent removed and treated by biological aerobic digestion ( air pumped trough water to encourage bacteria break down organic matter)
  • sludge uses anaerobic digestion releasing methane gas used as an energy source and rest of digested waste can be used as fertiliser - tocxic use UV radiation
• Haber process?

  • nitrogen obtained from air, hydrogen frim methane and steam forming hydrogen and carbon dioxide
  • reactant gases passed over iron catalyst 450 C 200ATM
  • reversible , dynamic equilibriu
  • ammonia formed aas a gas but when cooled in condenser it is liquified and removed , unused hydrogen is recycled so no waste
  • ammonia can make ammonium nitrate - fertilser