Question

3. Is a solution of sodium dihydrogen citrate, NaH2Cit,likely to be acidic, basic, or neutral? Show with equilibrium reactions how you know. Citric acid, H3 Cit, is H3CH507 (Use data from Table 16.5 or Appendix D in the textbook as necessary)

Answer 1

NaH2Cit is acidic . it has still two acidic protons to donate and it will be acidic

H₂Cit^- <-----------------------------> HCit^2- + H⁺

HCit^2- <----------------------------> Cit^3- + H⁺

another way also there to prove it is an acid

and also we can know that Ka values of this acid

Ka values of citric acid  

Ka1 = 7.4 x 10^-4 , pKa1 = 3.13

Ka2 = 1.7 x 10^-5 , pKa2 = 4.77

Ka3 = 4.0 x 10^-7 , pKa3 = 6.40

pH of NaH2Cit depends on pKa1 and pKa2

pH = 1/2 [3.13 + 4.77 ]

pH = 3.95

here this salt pH also less than 7 so it is acidic