Chemistry C3- Testing for Positive Ions

Flame test- Clean nichrome wire dipped in distilled water & heat in a fierce flame.

  • Lithium turns CRIMSON RED
  • Sodium turns YELLOWY ORANGE
  • Potassium turns LILAC
  • Calcium turns BRICK RED
  • Barium turns APPLE GREEN  (flames)
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  • Created by: Katie
  • Created on: 27-03-13 17:23

Testing for Postive Ions

  • Another test.- Metal Ion precipitates
  • Add 2-3 CM3 of metal ion solution
  • 10 drops of dilute sodium hydoxide solution

Copper turns cloudy and solidifys- Blue precipitate,

Iron turns Green precipitate

Iron (III) turns Reddish/Brown precipitate

Aluminium turns White precipitate (Adding more in excess it will dissolve)

Calcium turns cloudy

Magnesium turns White precipitate

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Testing for Negative Ions

Test- Carbonates,

  • 4 to 5 cm dilute hydochloric acid to marble chip into a test tube
  • Attach delivery tube & bubble gas (CO2) to produce through limewater.

                                     Heating before       Heating after

Copper Carbonate      GREEN                  BLACK

Zinc carbonate            WHITE                   YELLOW       

Equation- Calcium Carbonate- Hydrochloric acid----Calcium chloride +CO2+Water

                 CaCO3                     HcL (aq)                    CaCL2 (aq)         

Limewater turns cloudy/milky                                   

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Acid Based Titration

Equipment required:,

  • Goggles
  • 25cm pipette
  • Pipette filter
  • 50cm3 Burette
  • Small funnel for filling the burette
  • Clamp and Stand
  • White tile
  • 250cm3 conical flask
  • 0.4 mol/dm3 hydrochloric acid (low hazard) 150 cm3
  • 0.4 mol/dm3 sodium hydroxide (irritant) 150 cm3
  • Phenmolphthlein indicator
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