what is the function of rochelle salt in fehling solution B???

Asked by Anushri | 5th Feb, 2014, 09:56: PM

Expert Answer:

  • Fehling's A is a blue aqueous solution of copper (II) sulphate, while Fehling's B is a clear solution of aqueous potassium sodium tartrate (also known as Rochelle salt) and a strong alkali (commonly sodium hydroxide).
  • Equal volumes of the two mixtures are mixed together to get the final Fehling's solution, which is a deep blue colour.
  • In this final mixture, aqueous tartrate ions from the dissolved Rochelle salt chelate to Cu2+ (aq) ions from the dissolved copper(II) sulphate, as bidentate ligands giving the bistartratocuprate(II)4- complex.
  • The tartarate ions, by complexing copper prevent the formation of Cu (OH)2 from the reaction of CuSO4.2H2O and NaOH present in the solution.

Answered by  | 6th Feb, 2014, 09:40: AM

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