Title: Step-by-Step Qualitative Analysis of Nickel(II) Chloride (NiCl₂)

Introduction

Nickel(II) chloride (NiCl₂) is an inorganic compound used in electroplating, catalysts, and chemical synthesis. This document outlines the qualitative analysis of NiCl₂ to identify its cation (Ni²⁺) and anion (Cl⁻) through systematic tests.

Step-by-Step Analysis of NiCl₂

1. Preliminary Examination

Property	Observation
Physical Appearance	Green crystalline solid (NiCl₂·6H₂O)
Solubility	Soluble in water, forming a green solution
Odor	Odorless

2. Dry Heating Test

Procedure	Observation	Inference	Chemical Equation
Heat a small sample in a dry test tube.	Green crystals turn yellow and release water vapor.	Confirms presence of hydrated NiCl₂·6H₂O.	NiCl₂·6H₂O → NiCl₂ + 6H₂O

3. Identification of Nickel (Ni²⁺) Ion

Test	Reagent Used	Observation	Inference	Chemical Equation
Ammonia (NH₃) test	Aqueous NH₃	Blue-violet solution	Confirms Ni²⁺ presence	[Ni(H₂O)₆]²⁺ + 6NH₃ → [Ni(NH₃)₆]²⁺ + 6H₂O
Dimethylglyoxime (DMG) test	DMG reagent + NH₃	Red precipitate	Confirms Ni²⁺ presence	Ni²⁺ + 2C₄H₈N₂O₂ → Ni(C₄H₈N₂O₂)₂ (red ppt.)

4. Identification of Chloride (Cl⁻) Ion

Test	Reagent Used	Observation	Inference	Chemical Equation
Silver Nitrate (AgNO₃) test	AgNO₃ solution	White precipitate	Confirms Cl⁻ presence	NiCl₂ + 2AgNO₃ → 2AgCl (ppt.) + Ni(NO₃)₂
Conc. Sulfuric Acid (H₂SO₄) test	H₂SO₄ + heat	Colorless pungent gas (HCl) turns moist blue litmus paper red	Confirms Cl⁻ presence	NiCl₂ + H₂SO₄ → 2HCl + NiSO₄

Conclusion

The qualitative analysis of NiCl₂ confirms the presence of nickel (Ni²⁺) and chloride (Cl⁻) ions through distinct chemical reactions, solubility tests, and confirmatory tests.