Tests for cations and anions

• What’s the test for group 2 ions?

  . Add 10 drops of sample into test tube

  . Add 10 drops of sodium hydroxide solution

  . Continue adding sodium hydroxide until in excess

  
  

  Results:

  . Mg2+ : White ppt

  . Ca2+ : Slight white ppt

  . Sn2+ : Slight white ppt

  . Ba2+ : Colourless
• What is the test for NH4+?

  . Add 10 drops of the sample to test tube

  . Add 10 drops of sodium hydroxide solution

  . Add test tube to water bath

  . Place red litmus paper on top of test tube

  
  

  Results:

  . If NH4+ ion is present, paper will turn blue
• Test for Sulphate ion

  . Add 10 drops of sample into test tube

  . Add 10 drops of Barium chloride to test tube

  
  

  Result :

  . If sulphate ions are present a white ppt forms
• What is the test for Halide ions?

  . Add 10 drops of sample into test tube

  . Add 10 drops of Nitric acid to test tube

  . Add 10 drops of silver nitrate to solution

  Results :

  . Fluorides: no ppt

  . Chlorides: white ppt

  . Bromides: cream ppt

  . Iodides: pale yellow ppt
• What is the test for carbonate ions?

  . Add dilute acid

  . Bubble the gas produced through limewater

  Results :

  . If carbonate ions present the limewater will turn cloudy
• Testing for hydroxide ions

  . Any alkaline hydroxides will turn red litmus paper blue