C3-analysis and synthesis

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tests for positive ions

  • some positive ions can be identified by doing a flame test of sodium hydroxide solution
  • LITHIUM (Li)= CRIMSON
  • SODIUM(Na)=YELLOW
  • POTASSIUM(K)=LILAC
  • CALCIUM(Ca2+)=RED
  • BARIUM(Ba2+)=GREEN
  • LITTLE SLIMEY POOS CRACK BUMHOLES/CREEPY YELLOW LEMONS READ GRAZIA
  • metals that have ions with a 2+ or 3+ are insoluble in water, a precipitate is formed
  • aluminium, calcium and magnesium form white precipitate
  • when excess sodium hydroxide solution is added to the precipiate of aluminium hydoxide dissolves
  • copper 2 hydroxide = blue
  • iron 2 hydroxide= green
  • iron 3 hydroxide= brown

tests for negative ions

  • there are three tests carbonate, halide and sulfate
  • to see if a substance contains carbonate you add dilute hydrochloric acid to substance to see if it fizzes if it does and the gas produced turns limewater milky the substance contains carbonate ions
  • to see if a substance contains halide ions you add dilute nitric acid and then silver nitrate solution chloride ions give you white precipitate, bromide ions give you cream precipitate and iodide ions give a yellow precipitate
  • to test for sulfate ions add hydrochloric acid and then barium chloride solution, if a white precipitate forms sulfate ions are present

titrations

  • when solutions of an acid and an alkali form a salt and a water neutralisation takes place
  • volumes of solutions that react can be found by titration
  • titration- use a pipette to measure accuratley the vol of alkali put into conical flask, indicator is added to…

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