Analisis Kation Golongan II (Tugas Presentasi Mahasiswa TLM UNBI)

Introduction

This tutorial provides a step-by-step guide to understanding and analyzing Group II cations in qualitative analysis, based on a presentation by students from Universitas Bali International. This topic is crucial in chemistry for identifying metal ions through their characteristic reactions, and it is particularly relevant for students in analytical chemistry.

Step 1: Understanding Group II Cations

Group II cations include elements such as magnesium, calcium, strontium, and barium. These cations are known for their similar chemical properties.

• Key Characteristics:
  • They typically form insoluble hydroxides and sulfates.
  • Their reactions can be identified through various qualitative tests.

Step 2: Preparing the Sample

Before conducting tests, it is essential to prepare your sample properly.

• Materials Needed:

  • Test tubes
  • Dilute hydrochloric acid (HCl)
  • Distilled water
  • Reagents for specific tests (e.g., sodium sulfate, ammonium sulfate)

• Sample Preparation Steps:

  1. Dissolve the sample in dilute HCl.
  2. Filter any undissolved solids to obtain a clear solution.

Step 3: Conducting Preliminary Tests

Conduct preliminary tests to identify the presence of Group II cations.

• Common Tests:
  • Flame Test: Introduce a small amount of the sample to a flame and observe the color.
    • Calcium: Orange-red
    • Strontium: Crimson
    • Barium: Green
  • Add a few drops of sodium sulfate to the solution and observe any precipitate formation.

Step 4: Confirmatory Tests

Perform confirmatory tests to accurately identify the specific Group II cations present.

• Calcium Test:

  • Add ammonium oxalate to form calcium oxalate precipitate (white).

• Strontium Test:

  • Add sulfuric acid to form strontium sulfate precipitate (white).

• Barium Test:

  • Add dilute sulfuric acid to check for barium sulfate precipitate (white).

Step 5: Analyzing Results

Carefully analyze the results from your tests to determine which cations are present.

• Considerations:
  • Compare the color and solubility of precipitates formed.
  • Use a control sample for comparison if needed.

Conclusion

In this guide, we covered the essential steps for analyzing Group II cations, from sample preparation to conducting tests and analyzing results. Understanding these procedures is vital for students and professionals in chemistry.

For further study, consider practicing with real samples and exploring advanced analytical techniques such as spectroscopy for more precise identification of metal ions.