Question

Predict whether aqueous solutions of the salts will be acidic, basic or neutral. Please explain why, so that I can learn the mechanism. Thank you!

Acidic Basic Neutral  (CH₃)₂NH₂NO₃
Acidic Basic Neutral  C₆H₅NH₃Br
Acidic Basic Neutral  CaBr₂
Acidic Basic Neutral  CsF₃CCOO
Acidic Basic Neutral  Cs(NO₃)

Answer 1

Acidic   (CH₃)₂NH₂NO₃    It is salt of strong acid(HNO3) and weak base (CH3)2NH
Acidic C₆H₅NH₃Br           it is a salt of strong acid (HBr) and weak base C6H5NH2
Acidic   CaBr₂                    it is a salt of strong acid(HBr) and weak base _Ca(OH)2
Basic CsF₃CCOO          it is a salt of strong base (CsOH) and weak acid (CF3COOH)
Neutral  Cs(NO₃)           it is a salt of strong base (CsOH) and strong acid HNO3

Acidic   (CH₃)₂NH₂NO₃

(CH₃)₂NH₂NO₃   is acidic due to cationic hydrolysis

         (CH3)2NH2NO3(aq) --------------> (CH3)2NH2^+ (aq) + NO3^- (aq)

cationic hydrolysis

   (CH3)2NH2^+ (aq) + H2O ------------> (CH3)2NH (aq) + H3O^+ (aq)
Acidic C₆H₅NH₃Br

C6H5NH3Br is acidic due to cationic hydrolysis

C6H5NH3Br(aq) ---------------> C6H5NH3^+ (aq) + Br^- (aq)

cationic hydrolysis

C6H5NH3^+(aq) + H2O ------------> C6H5NH2(aq) + H3O^+ (aq)
Acidic   CaBr₂

CaBr2 is acidic due to cationic hydrolysis
Basic CsF₃CCOO

CsF₃CCOO is basic due to anionic hydrolysis

CsF₃CCOO(aq) --------------> Cs^+ (aq) + F3C-COO^- (aq)

F3C-COO^- (aq) + H2O--------------> F3C-COOH(aq) + OH^- (aq) anionic hydrolysis
Neutral  Cs(NO₃)

CsNO3 is neutral due to no cationic and anionic hydrolysis