What are the net ionic equations for the hydrolysis of the the following:
- NaC2H3O2 2. Na2CO3 3. NH4CL 4.ZnCl2 5.KAl (SO4)2 6.KAl(SO4)2 for 5 & 6 there are supposed to be 2 different hydrolysis reactions occurring Also determine if each is Ka or Kb
The Correct Answer and Explanation is :
Net Ionic Equations for Hydrolysis Reactions
- Sodium Acetate (NaC₂H₃O₂)
- Reaction:
[
C_2H_3O_2^- + H_2O \rightleftharpoons HC_2H_3O_2 + OH^-
] - Type: Base hydrolysis (( K_b )), since acetate (( C_2H_3O_2^- )) is the conjugate base of a weak acid (acetic acid, ( HC_2H_3O_2 )).
- Sodium Carbonate (Na₂CO₃)
- Reactions: (Stepwise hydrolysis of carbonate)
[
CO_3^{2-} + H_2O \rightleftharpoons HCO_3^- + OH^-
]
[
HCO_3^- + H_2O \rightleftharpoons H_2CO_3 + OH^-
] - Type: Base hydrolysis (( K_b )), since carbonate acts as a weak base.
- Ammonium Chloride (NH₄Cl)
- Reaction:
[
NH_4^+ + H_2O \rightleftharpoons NH_3 + H_3O^+
] - Type: Acid hydrolysis (( K_a )), since ammonium (( NH_4^+ )) is the conjugate acid of ammonia.
- Zinc Chloride (ZnCl₂)
- Reaction:
[
Zn^{2+} + 2H_2O \rightleftharpoons Zn(OH)_2 + 2H^+
] - Type: Acid hydrolysis (( K_a )), since ( Zn^{2+} ) hydrolyzes to release ( H^+ ), making the solution acidic.
- Potassium Aluminum Sulfate (KAl(SO₄)₂) – First Hydrolysis
- Reaction:
[
Al^{3+} + 3H_2O \rightleftharpoons Al(OH)_3 + 3H^+
] - Type: Acid hydrolysis (( K_a )), since ( Al^{3+} ) hydrolyzes and produces ( H^+ ).
- Potassium Aluminum Sulfate (KAl(SO₄)₂) – Second Hydrolysis
- Reaction:
[
SO_4^{2-} + H_2O \rightleftharpoons HSO_4^- + OH^-
] - Type: Base hydrolysis (( K_b )), since sulfate acts as a weak base.
Explanation (300 Words)
Hydrolysis occurs when ions from a salt react with water to form acidic or basic solutions. The determining factor is whether the salt’s cation or anion originates from a strong or weak acid or base.
- Sodium acetate (NaC₂H₃O₂) hydrolyzes because acetate (( C_2H_3O_2^- )) is the conjugate base of a weak acid (acetic acid). It reacts with water to produce hydroxide ions (( OH^- )), making the solution basic (( K_b )).
- Sodium carbonate (Na₂CO₃) undergoes stepwise hydrolysis. The carbonate ion (( CO_3^{2-} )) is a strong base and reacts with water to form bicarbonate (( HCO_3^- )) and hydroxide ions (( OH^- )), increasing the pH (( K_b )).
- Ammonium chloride (NH₄Cl) contains ammonium (( NH_4^+ )), the conjugate acid of ammonia. It donates a proton to water, forming hydronium (( H_3O^+ )), making the solution acidic (( K_a )).
- Zinc chloride (ZnCl₂) undergoes hydrolysis because ( Zn^{2+} ) is a small, highly charged metal ion. It interacts with water, forming zinc hydroxide and releasing protons, thus decreasing the pH (( K_a )).
- Potassium aluminum sulfate (KAl(SO₄)₂) has two hydrolysis reactions:
- Aluminum ion (( Al^{3+} )) hydrolyzes, producing ( H^+ ), making the solution acidic (( K_a )).
- Sulfate ion (( SO_4^{2-} )) hydrolyzes weakly, producing ( OH^- ), contributing to basicity (( K_b )).
The net effect of these hydrolysis reactions determines whether the salt solution is acidic or basic, impacting real-world applications like buffer solutions and industrial chemistry.