Group II Cations Schematic Diagram PDF

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ANALYTICAL CHEM 1ST SEM...

Description

Name: Condrillon, Choren G.

Date: February 4, 2021 Experiment No.2

Schematic Diagram for the Separation of Group 2 Cations 3 ml of unknown solution Containing Group II Cations: As+3, Bi+3, Cd+2, Cu+2, Hg+2, Sb+3, Sn+2

test its acidity or alkalinity with red or blue litmus.

If acidic

add 6M HCl until acidic then add 2 drops of 3% H2O2 solution.

add 2 drops of 3% H2O2 solution.

If alkaline

Formation of dark precipitate indicates the presence of ions from group II. vaporate by adding 10 drops of 6M NH4OH to neutralize, then add 6 to 10 drops of 6M HCl until olution is acidic. Add 0.5 mL water and transfer the suspension to (b) dd 20 drops of 1M thioacetamide ( C2H5NS) and dilute to 4mL. ap with a deflated balloon then water bath for 10 mins. Without uncapping the tube cool it by mmersing with cold water. gitate the cooled tube for 1 minute to re-dissolve the trapped H2S gas. entrifuge and decant

Solution to be discarded (supernatant)

Colored Precipitate indicate presence of the sulfide group a. Centrifuge then add 1 to 2 mL of water and 2 drops of 5M NH4NO3. Agitate to bring the solids into suspension. b. Add 1 mL of water to remove any solids adhering to the side of the tube, centrifuge, and discard the wash solution.

Supernatant

Residue Wash the residue with 1-2mL of water containing 2 drops of 5M NH4NO3 , then centrifuge and decant.

Discard washed solution

*Decant then test the acidity with methyl violet paper. If the [H+] exceeds 0.3M, add a drop of 1M NH4OH and test again. *For complete precipitation, add 5 drops of 1M thioacetamide. Capping the test tube and water bath it for 10 minutes. If additional precipitate is formed, pour the suspension containing the previously precipitated sulfides then centrifuge and decant to ensure complete separation from sulfide precipitate.

Group II A (Cu+2 group) and Group II B (Arsenic group) Add 2mL of 0.5M KOH and water bath for 2 mins. then centrifuge and decant.

Supernatant (As)

Residue (Cu) Contains ions from the copper group

Contains ions from the arsenic group a. Add 10 to 15 drops of concentrated HCl, water bath until precipitate dissolves. Centrifuge and decant. Evaporate the supernatant liquid until approximately 4 drops, add 2ml of water.

a. Add 2 drops of 5M NH4NO3 then rinse with water, and centrifuge. Add 1mL of 6M HNO3 and water bath for 2 minutes. b. Centrifuge and discard residue containing solid sulfur. c. Add drops of 15M NH4OH to the supernatant liquid ( c) until basic. Centrifuge and filter the separate residue from liquid.

Sb+3 Deep blue colored solution indicates presence of Cu+2 Acidify with 6M acetic acid then add 3 drops of 2M K4[Fe(CN)6], then

White residue indicates presence of Bi+3 Wash in the filter paper with 1mL of water. Pour drops of sodium stannate to the residue. Centrifuge and decant.

Add 6M NH4OH until red litmus paper turns blue and blue litmus paper turns blue. Add 6M CH3COOH until litmus indicates acidic, add one drop of acid in

Sn+2 Add small iron nail and water bath the test tube for 5 to 10 mins. Decant. Add 2 drops of 0.1M...