Question

Question: Are solutions of the following salts acidic, basic, or neutral? For those that are not neutral, explain why the solution is acidic or basic. The relevant K_a and K_b values are found in Tables 7.2, 7.3, and 7.4.

a. Sr(NO₃)₂

b. C₂H₅NH₃CN

c. C₅H₅NHF

d. NH₄C₂H₃O₂

e. NaHCO₃

Short answer

Answer

Sr(NO₃)₂ : Neutral

C₂H₅NH₃CN : Basic

C₅H₅NHF : Acidic

NH₄C₂H₃O₂ : Neutral

NaHCO₃ : Basic

Step-by-step solution

Composition of Various Salts 

Sr(NO₃)₂ : Salt of strong acid H NO₃ and strong base Sr(OH)₂, so the salt is neutral.

C₂H₅NH₃CN : Salt of weak acid HCN (K_a = 6.2×10^-10)

and weak base C₂H₅NH₂ (K_b = 5.6×10^-4)

C₅H₅NHF : Salt of strong acid HF (K_a = 7.2×10^-4)

and weak base C₅H₅N (K_b = 1.7×10^-9)

NH₄C₂H₃O₂ : Salt of weak acid CH₃COOH (K_a = 1.8 ×10^-5)

and weak base NH₃ (K_b = 1.8 ×10^-5)

NaHCO₃ :Salt of weak acid H₂CO₃ and strong base NaOH (solution basic)

Sr(NO3)2

Hence, Sr(NO₃)₂is a neutral salt.

C2H5NH3CN 

C₂H₅NH₃CN : Salt of weak acid HCN (K_a = 6.2×10^-10)

and weak base C₂H₅NH₂ (K_b = 5.6×10^-4)