GROUP 1 CATION ANALYSIS (FINALS ANACHEM LAB)

• QUALITATIVE ANALYSIS


  it is a method used for identification of ions or compounds in a sample
• In qualitative analysis, the IDENTIFY of metal ions present (not the amount) in a mixture is determined
• In qualitative analysis, it's important to take note the shape and color of a precipitate
• REAGENTS are used to separate cations into group of related elements
• IONS in a group are separated from each other
• WHAT GROUP PRECIPITATED IN 1 M HCL?

  GROUP 1 Ag+, Hg2 2+, Pb2+
• WHAT GROUP PRECIPITATED IN A 0.1 M H2S (HYDROGEN SULFIDE) SOLUTION AT PH 0.5

  GROUP 2 Bi3+, Cd2+, Cu2+
• WHAT GROUP IS PRECIPITATED IN 0.1 M H2S (HYDROGEN SULFIDE) SOLUTION AT PH 9?

  GROUP 3 Al3+, Co2+, Cr3+
• WHAT GROUP PRECIPITATED IN 0.2 M (NH4) 2CO3 (AMMONIUM CARBONATE) SOLUTION AT PH 10

  GROUP 4 Ba2+, Ca3+, K
• 6M HCL

  
  

  • destroys hydroxo and NH3 complexes
  • precipitates insoluble chlorides
• 6M HNO3

  • dissolves insoluble sulfides by oxidizing sulfide ion
  • destroys hydroxo and ammonia complexes
  • good oxidizing agent when hot
• 6M NaOH

  • forms hydroxo complexes
  • precipitates insoluble hydroxides
• 6M NH3


  • precipitates insoluble hydroxides
  • forms NH3 complexes
  • forms a basic buffer with NH4+
• HOW MANY DROPS IN 1.0 ml?

  10-15 drops
• WHAT COLOR OF PRECIPITATE CONFIRMS THE PRESENCE OF Ag+?

  White Precipitate
• WHAT COLOR OF PRECIPITATE CONFIRMS THE PRESENCE OF Pb2+?

  Yellow Precipitate
• WHAT COLOR OF PRECIPITATE CONFIRMS THE PRESENCE OF Hg2+2?

  Gray Precipitate
• WHAT MIXTURE IS ADDED IN A MIXTURE OF GROUP 1 CATION TO PRECIPITATE THE SOLUTION?

  2 DROPS OF 6M HCl
• WHAT PRECIPITATE or PRODUCT IS PRODUCED WHEN YOU ADDED 6M HCl INTO GROUP 1 MIXTURE?

  • WHITE PRECIPITATE OF AgCl, Hg2Cl2, PbCl2
  • Insoluble Chlorides
• WHAT IS THE CONTENT OF THE SUPERNATANT SOLUTION OF THE MIXTURE GROUP 1 CATIONS AND 6M HCl?

  • Group 2-5
• WHEN YOU ADD HOT WATER AND CENTRIFUGE THE MIXTURE OF GROUP 1 CATION AND HCl, WHAT PRODUCT IS PRODUCED?

  • WHITE PRECIPITATE OF AgCl and Hg2Cl2
  • Supernatant solution that contains Pb2+
• WHAT SOLUTION DO YOU ADD TO CONFIRM THE PRESENCE OF Hg2+2?

  10-12 drops of 6M NH3 (ammonia)
• TO CONFIRM THE PRESENCE OF Pb2+, WHAT SOLUTION IS ADDED?

  • 1 drop of 6M HC2H3O2 (acetic acid)
  • 3-4 drops of K2CrO4 (potassium chromate)
• TO CONFIRM THE PRESENCE OF Ag2+, WHAT SOLUTION IS ADDED?

  6M NHO3 (nitric acid)
• PROCEDURE OF GROUP 1 CATION ANALYSIS (PART 1)

  1. mixed 1.0 ml of 0.1M AgNO3, 0.2M Pb(NO3), and 0.1M Hg2 (NO3) to identify Group 1 Cations
  2. Add HCl to precipitate cations (white precipitate) and separate them by centrifugation and remove impurities by washing.
  3. Heat the clean precipitate with hot water bath for 3-4 minutes. Then, centrifuge the mixture and save the white precipitate of Ag2+ and Hg2+2, and the supernatant solution that contains Pb2+
• PROCEDURE OF GROUP 1 CATION ANALYSIS (PART 2)

  
  

  4. To confirm the presence of Pb2+, it is tested with HC2H3O2 (acetic acid) and K2CrO4 (potassium chromate) to confirm Pb2+ ions. Pb2+ is identified by yellow precipitate.

  
  

  5. Then add 6M NH3 (ammonia) to the saved white precipitate of Ag2+ and Hg2+2, and centrifuged the mixture. The gray precipitate in the mixture confirms the presence of Hg2+2, and the supernatant solution after centrifuged contains Ag2+ ions

  
  

  6. To confirm the presence of Ag2+, add NHO3 (nitric acid) to the solution. A white precipitate produced confirms the presence of Ag2+
• GIVE 3 GROUP 1 CATIONS

  • Ag2+ (Silver)
  • Hg2+2 (Mercury)
  • Pb2+ (Lead)
• GROUP 1 CATIONS IS ALSO KNOWN AS?

  Alkali Metal Cations
• The formation of white precipitate of AgCl in the acidic solution is confirmation of the presence of Ag+
• PREPARE

  POUR

  CENTRIFUGE

  ADD

  DECANT