Question

what is the function of roschelle salt in fehling solution?

Answer 1

what is the function of rochelle salt in fehling solution B??? Answer: Fehling's A is a blue aqueous solution of copper (II) sulphate, while Fehling's B is a clear solution of aqueouspotassium sodium tartrate (also known as Rochelle salt) and a strong alkali (commonly sodium hydroxide

Answer 2

2 answers · Chemistry 

 Best Answer

Fromhttp://columbia.thefreedictionary.com/Fe... 

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). 

So the tartrate part of Rochelle salt is the key reactant. 

In the case of sodium citrate: the cupric ion (complexed with citrate ions) is reduced to cuprous ion by the aldehyde group (which is oxidized), and precipitates as cuprous oxide, Cu2O. 

Thus the citrate is key to the reaction.