Chemistry - The ion tests

these are the tests for positive and negative ions 

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Testing For Positive ions.

Flame Test: 

  • Lithium: Crimson/Red
  • Sodium: Orange/Yellow
  • Pottasium: Lilac
  • Calcium: Brick Red
  • Barium: Green

Hydroxide of metal + Sodium Hydroxide:

(Aluminium or Calcium or Magnesium) + NaOH = White precipitate

Aluminium + excess NaOH, the precipitate dissolves.

  • Copper (II) hydroxide = Blue precipitate
  • Iron (II) hydroxide = Green precipitate
  • Iron (III) hydroxide = Brown precipitate
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Testing For Negative ions.

Carbonate ions: Add dilute Hydrochloric acid and see if it fizzes. If it does and the gas produced turns limewater cloudy, the substance contains carbonate ions.

Halide ions: Add dilute Nitric acid and then Slive NItrate solution.

  • Chloride ions: White precipitate
  • Bromide ions: Cream precipitate
  • Iodide ions: Yellow precipitate

Sulfate ions: Add dilute Hydrochloric acid and the Barium CHloride solution. Form white precipitate.

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