# Salt hydrolysis problems and solutions

1. What is salt hydrolysis? Solution: Salt hydrolysis is a reaction in which a salt reacts with water to form an acidic or basic solution. This occurs when the ions of the salt react with the hydrogen ions (H⁺) or the hydroxide ions (OH⁻) from water.

2. What are the products of the hydrolysis of a salt of a weak acid and a strong base? Solution: The products of the hydrolysis of a salt of a weak acid and a strong base are a weak acid and water. The solution formed is basic because the weak acid ionizes less than the water.
3. What are the products of the hydrolysis of a salt of a strong acid and a weak base? Solution: The products of the hydrolysis of a salt of a strong acid and a weak base are a weak base and water. The solution formed is acidic because the weak base ionizes less than the water.
4. How is the hydrolysis constant (Kᵦ) related to the ionization constant of water (Kw) and the ionization constant of the weak acid (Ka)? Solution: The hydrolysis constant (Kᵦ) is related to the ionization constant of water (Kw) and the ionization constant of the weak acid (Ka) by the equation Kᵦ = Kw/Ka.
5. What is the hydrolysis equation for the salt NH₄Cl? Solution: The hydrolysis equation for the salt NH₄Cl is: NH₄⁺ + H₂O ⇌ NH₃ + H₃O⁺.
6. What type of solution (acidic, basic, or neutral) is formed by the hydrolysis of a salt of a strong acid and a strong base? Solution: The hydrolysis of a salt of a strong acid and a strong base results in a neutral solution because neither the cation nor the anion of the salt undergoes hydrolysis.
7. What type of solution (acidic, basic, or neutral) is formed by the hydrolysis of a salt of a weak acid and a weak base? Solution: The hydrolysis of a salt of a weak acid and a weak base can result in either an acidic or a basic solution. The pH depends on the relative strengths of the weak acid and the weak base.
8. What is the pH of the solution formed by the hydrolysis of a salt of a weak acid and a strong base? Solution: The solution formed by the hydrolysis of a salt of a weak acid and a strong base has a pH greater than 7 because it is basic.
9. What is the pH of the solution formed by the hydrolysis of a salt of a strong acid and a weak base? Solution: The solution formed by the hydrolysis of a salt of a strong acid and a weak base has a pH less than 7 because it is acidic.
10. What is the hydrolysis equation for the salt CH₃COONa? Solution: The hydrolysis equation for the salt CH₃COONa is: CH₃COO⁻ + H₂O ⇌ CH₃COOH + OH⁻.
11. What is a hydrolysis constant? Solution: A hydrolysis constant is a measure of the degree of ionization of a salt in water. It is the equilibrium constant for the hydrolysis reaction.
12. How can the pH of the solution formed by the hydrolysis of a salt be calculated? Solution: The pH of the solution formed by the hydrolysis of a salt can be calculated by first determining the hydrolysis constant and then using the formula pH = -log[H₃O⁺] for acidic solutions or pH = 14 – -log[OH⁻] for basic solutions.
13. What are spectator ions in the context of salt hydrolysis? Solution: Spectator ions are ions that do not participate in the hydrolysis reaction. They remain in the solution unchanged.
14. Why does the hydrolysis of a salt of a weak base and a strong acid result in an acidic solution? Solution: The hydrolysis of a salt of a weak base and a strong acid results in an acidic solution because the weak base ionizes less than the water, producing more H₃O⁺ ions and thus lowering the pH.
15. Why does the hydrolysis of a salt of a weak acid and a strong base result in a basic solution? Solution: The hydrolysis of a salt of a weak acid and a strong base results in a basic solution because the weak acid ionizes less than the water, producing more OH⁻ ions and thus raising the pH.
16. Can the hydrolysis of a salt of a strong acid and a strong base change the pH of the solution? Solution: No, the hydrolysis of a salt of a strong acid and a strong base cannot change the pH of the solution. Neither the cation nor the anion of the salt undergoes hydrolysis, so the pH remains neutral.
17. How does temperature affect salt hydrolysis? Solution: An increase in temperature usually increases the rate of salt hydrolysis because higher temperatures provide more kinetic energy to the molecules, allowing them to overcome the activation energy barrier more easily.
18. How does the concentration of the salt affect the degree of its hydrolysis? Solution: The degree of hydrolysis of a salt is inversely proportional to the square root of its concentration. This means that a higher concentration of the salt results in a lower degree of hydrolysis.
19. What is the hydrolysis equation for the salt Na₂SO₄? Solution: The hydrolysis equation for the salt Na₂SO₄ is: Na⁺ + H₂O ⇌ NaOH + H⁺. However, as Na⁺ is the cation of a strong base (NaOH), it does not undergo hydrolysis in practice. Therefore, Na₂SO₄ does not change the pH of the solution.
20. What is the hydrolysis equation for the salt AlCl₃? Solution: The hydrolysis equation for the salt AlCl₃ is: Al³⁺ + H₂O ⇌ Al(OH)²⁺ + H⁺. The solution formed is acidic due to the presence of H⁺ ions.