Metal Ion Identification: Experimental Study on Ionization and Reactions

Introduction

This experimental study focuses on exploring concepts related to the ionization of metals. By using chemical reagents, one can understand how these metals react and differentiate them qualitatively. Through observation of the reactions, such as color changes or the formation of precipitates, one can gain insights into the cations present in each solution (Zheng et al., 2020). These findings will greatly contribute to our understanding of the properties and characteristics of metal ions.

Materials

• (6) Test Tubes 10 x 75 mm Test Tube Rack Medicine droppers
• 3 M HNO_{3 (aq)}
• 3 M NH_{3 (aq)}
• 0.1M of each of the following: AgNO₃, Ba (NO₃)₂, Fe (NO₃)₃ Hg (NO₃)₂, Pb (NO₃)₂, NaI, NaOH, K₂CrO₄, (NH₄)₂SO₄, NaCl.

Procedure

1. Label your test tubes to prevent mixing solutions.
2. Make the 0.1 M of AgNO3, Ba(NO₃)₂, Fe(NO₃)₃, Hg(NO₃)₂, Pb(NO₃)₂, NaI, NaOH, K₂CrO₄, and (NH₄)₂SO₄ for testing purposes of presence of various metals.
3. If you want to examine for example silver, you should add 2-3 drops of AgNO₃ in the test tube. Thereafter, little drops of 3 M HNO₃ should be added to acidify it.
4. Next, fill the test tube with a few drops of 3 M NH₃, or ammonia. This stage helps in the differentiation of various metal cations according to the precipitate formation.
5. Check if there any changes in the solution. The change in color or formation of precipitate is an indication that there is presence of particular metal ions.
6. Redo steps 3, 4, and 5 for each metal ion you want to test. Remember to rinse all your droppers and test tubes very well to avoid contamination.

Scheme for Identification

Preliminary Tests

• Add 1-2 drops of 3 M HNO₃ to the solution to acidify it.
• Add 2 -3 drops of 3 M NH3 to check for the formation of precipitates.

Specific Tests

• Ag+

  • Add HNO₃.
  • Add a few drops of 0.1 M NaCl. When white precipitate is form, it is an indication that Ag+ present.
• Ba2+

  • Add HNO₃.
  • Add a small amount of 0.1 M Na₂SO₄.
  • When a white precipitate is formed, it is an indication that barium (Ba₂₊) is present.
• Fe3+

  • Acidify (HNO₃).
  • Add a few drops of K₂CrO₄.
  • A reddish-brown precipitate (Fe₂(CrO₄)₃) suggests the presence of Fe₃₊.
• MeHg2+

  • Add HNO₃.
  • Add 2-4 drops of 0.1 M Na₂SO₄.
  • When a white precipitate is formed, it suggests there is presence of Hg₂₊.
• Lead (Pb2+)

  • Add HNO₃.
  • Add 1-3 drops of 0.1 M K₂CrO₄.
  • A yellow precipitate (PbCrO₄) is observed, which indicates the presence of Pb₂₊.
• (I-)

  • Add two drops of HNO₃ to acidify.
  • Add little drops of 0.1 M AgNO₃.
  • The formation of a yellow precipitate (AgI) confirms the presence of I-.
• (Na+)

  • No specific reagent is required. Sodium ions do not leave the solution until they mix with another particular kind of ion.
• (OH-)

  • Add a few drops of NaOH to the solution.
  • When a colored or white precipitate forms indicates presence of a certain metal hydroxide.

Conclusion

In summary, this experiment in qualitative analysis successfully demonstrated the fundamentals of metal ion identification via systematic chemical testing. Differentiations and confirmations about the existence of different cations were made by acidifying the solutions and using particular reagents; these were based on distinctive reactions and precipitate formation. The knowledge of the qualitative analysis of metal ions in chemical analysis is established by this experiment.

Reference

Zheng, X., Cheng, W., Ji, C., Zhang, J., & Yin, M. (2020). Detection of metal ions in biological systems: A review. Reviews in Analytical Chemistry, 39(1), 231–246. Web.