How do you prepare Fehling solution?

Answer 1

fehling's solution is dark blue at room temperature

"Fehling's solution" is prepared by dissolving separately 34'639 grammes of copper sulphate, 173 grammes of Rochelle salt, and 71 grammes of caustic soda in water, mixing and making up to l000 ccs.; 10 ccs. of this solution is completely reduced by o 05 grammes of hexose

Answer 2

To prepare Fehling solution, you need to mix equal parts of two separate solutions: Fehling solution A (copper sulfate dissolved in water) and Fehling solution B (sodium potassium tartrate and sodium hydroxide dissolved in water). These solutions are then mixed together in equal amounts before use in the Fehling test for reducing sugars.

Answer 3

Fehling's solution is prepared just before use by mixing equal volumes of two previously prepared solutions, one containing about 70 grams cupric sulfate pentahydrate per liter of solution and the other containing about 350 grams Rochelle salt (potassium sodium tartrate tetrahydrate) and 100 grams sodium hydroxide per liter of solution. The cupric ion (complexed with tartrate ion) is reduced to cuprous ion by the aldehyde (which is oxidized) and precipitates as cuprous oxide (Cu2O); for this reason, sugars that react with Fehling's solution are called reducing sugars.

Answer 4

Fehling's solution is mixed because it takes Fehling's A and Fehling's B to make the solution. The solution needs to be prepared fresh before it is used.