Experiment Name: Qualitative test for known supplied a salt sample of Fe²⁺

Principle:

Each salt has two types of ions or radicals. One is cation from the basic part & another is an anion which comes from the acidic part. The basic part is positively charged & the acidic part is negatively charged. When the suitable reagent is added into the aqueous solution of a salt, the ions being precipitated and showed their own characteristics.

Reactions of Fe²⁺ solution:

1.      Stock solⁿ + NH₃ [NH₄CL + NH₄OH ---------> white Fe(OH)₂

2.     Solution + NaOH --------> white ppt. of Fe(OH)₂-------> Any acid soluble.

3.     Solution + K₄[Fe(CN)₆ ------->  white ppt. of  K₂Fe[Fe(CN)₆].

4.     Solution + NH₄CNS ---------> Black ppt. of FeS --------> Soluble in acid.

Reagents:

·       Stock solution

·       Sodium hydroxide (NaOH)

·       Potassium Ferro cyanide K₄[Fe(CN)₆

·       Ammonium thiocyanate (NH₄CNS)

Apparatus:

·       Test tubes

·       Dropper

·       Measuring Cylinder

·       Burner

Procedure:

At first prepare stock solution, then mix different reagents and used in different amount with the sample to be confirmed about the presence of Fe²⁺.

Result:

Fe²⁺ present

Comment:

Dark blue, white greenish, light blue, no change precipitate confirmed the presence of Fe²⁺  

Precaution:

• Need to wear an apron, hand gloves, masks, and goggles to protect eyes in the laboratory.
• Have to careful during the experiment.
• Hands must be washed before leaving the lab.