Division IV PREPARATION OF FEHLING’S SOLUTIONS
United Kingdom
In a graduated flask dissolve 69,278 g of pure crystallised copper sulphate — Analytical Reagent (CuSO4 5H2O) — free from iron in distilled water and bring the volume to 1 litre with distilled water. The correct strength of this solution must be verified by a quantitative determination of the copper.
In a graduated flask dissolve 100 g of sodium hydroxide and 346 g of double sodium potassium tartrate (Rochelle salt) in distilled water and bring the volume to 1 litre with distilled water.
The two solutions A and B must be mixed in equal quantities immediately before use. 10 ml of Fehling’s solution (5 ml of solution A and 5 ml of solution B) is completely reduced, under the conditions described at section III, by 0,04945 g of anhydrous dextrose.