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Assertion:- Degree of hydrolysis and pH ...

Assertion`:-` Degree of hydrolysis and pH of a `WAWB` salt is independent of initial concentration of salt.
Reason`:-` The solution of `NH_(4)CN` in water has pH slightly greater than ?

A

If both Assertion & Reason are True & the Reason is a correct explanation of the Assertion.

B

If both Assertion & Reason are True but Reason is not a correct explanation of the Assertiion.

C

If Assertion is True but the Reason is False.

D

If both Assertion & Reason are False

Text Solution

AI Generated Solution

The correct Answer is:
To solve the question regarding the assertion and reason provided, we will analyze both statements step by step. ### Step 1: Analyze the Assertion **Assertion:** The degree of hydrolysis and pH of a weak acid-base (WAWB) salt is independent of the initial concentration of the salt. - **Explanation:** The degree of hydrolysis (H) for a salt is given by the formula: \[ H = \sqrt{\frac{K_w}{K_a \cdot K_b}} \] where \( K_w \) is the ion product of water, \( K_a \) is the dissociation constant of the weak acid, and \( K_b \) is the dissociation constant of the weak base. - The formula shows that the degree of hydrolysis depends only on the constants \( K_a \) and \( K_b \) and not on the initial concentration of the salt. Thus, the assertion is correct. ### Step 2: Analyze the Reason **Reason:** The solution of \( NH_4CN \) in water has a pH slightly greater than 7. - **Explanation:** \( NH_4CN \) is a salt formed from a weak base \( NH_4OH \) (ammonium hydroxide) and a weak acid \( HCN \) (hydrocyanic acid). - When dissolved in water, the hydrolysis of \( NH_4^+ \) and \( CN^- \) occurs. Since \( HCN \) is a stronger acid than \( NH_4OH \) is a base, the solution will be slightly acidic. - Therefore, the pH of the solution of \( NH_4CN \) will be slightly less than 7, not greater than 7. Thus, the reason is incorrect. ### Conclusion - The assertion is correct, while the reason is incorrect. Therefore, the correct option is that the assertion is true, but the reason is false. ### Final Answer The answer is **Option 3**: The assertion is true, but the reason is false. ---

To solve the question regarding the assertion and reason provided, we will analyze both statements step by step. ### Step 1: Analyze the Assertion **Assertion:** The degree of hydrolysis and pH of a weak acid-base (WAWB) salt is independent of the initial concentration of the salt. - **Explanation:** The degree of hydrolysis (H) for a salt is given by the formula: \[ H = \sqrt{\frac{K_w}{K_a \cdot K_b}} ...
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Knowledge Check

  • Assertion : Degree of hydrolysis and pH of a salt, e.g. NH_(4)CN is independent of concentration of NH_(4)CN Reason : The solution of NH_(4)CN in water has pH slightly greater than 7 .

    A
    If both assertion and reason are true and the reason is the correct explantion of the assertion.
    B
    If both assertion and reason are true but reason is not the correct explanation of the assertion.
    C
    If assertion is true but reason is false.
    D
    If assertion is false but reason is true.
  • The pH of which salt is independent of its concentration ?

    A
    `(CH_(3)COO)C_(5)H_(5)N`
    B
    `NaH_(2)PO_(4)`
    C
    `Na_(2)HPO_(4)`
    D
    `NH_(4)CN`
  • For which of the following salt pH of its aqueous solution is independent of concentration of salt.

    A
    `Na_(2)HPO_(3)`
    B
    `NaH_(2)PO_(2)`
    C
    `CH_(3)COONH_(4)`
    D
    `CH_(3)COONa`
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