Fehling’s Solution A

Fehling’s Solution A is an aqueous solution of copper(II) sulfate pentahydrate (CuSO4·5H2O), appearing as a deep blue liquid due to the presence of copper(II) ions. It is prepared by dissolving copper sulfate pentahydrate in distilled water, sometimes with the addition of a few drops of dilute sulfuric acid to stabilize the solution.

Composition of Fehling’s Solution A:

Copper(II) sulfate pentahydrate (CuSO4·5H2O), typically around 70 g per liter of solution

Distilled water as solvent

Occasionally small amounts of dilute sulfuric acid to maintain stability

Function and Uses:

Combined with Fehling’s Solution B (alkaline potassium sodium tartrate solution) immediately before use to form Fehling’s reagent

Used to detect reducing sugars and aldehydes in chemical analysis

The copper(II) ions in Fehling’s solution A are reduced to form red copper(I) oxide precipitate when aldehydes are present, indicating a positive result

Key Features:

Deep blue aqueous solution

Contains free Cu2+ ions as an oxidizing agent when mixed with solution B

Stored separately from Fehling’s Solution B to prevent premature reaction

This description fits well for laboratory reagent catalogs, educational content, and chemical supply listings related to Fehling’s test reagents.​