Question

Which statement is wrong about \(pH\) and \(H^+\)?

• A. pH of neutral water does not zero
• B. Adding 1N,1N solⁿ of CH₃COOH and NaOH pH will be seven
• C. pH of dilute and hot H₂SO₄ is more than concentrate and cold H₂SO₄
• D. Mixing solution of CH₃COOH and HCl, pH will be less than 7

Answer 1

The Correct Option is B

To determine which statement is incorrect about pH and H^+, let us evaluate each option:

1. pH of neutral water does not zero: This statement is true. The pH of neutral water at 25°C is typically 7, not zero. A pH of zero indicates a highly acidic solution.

2. Adding 1N,1N solⁿ of CH₃COOH and NaOH pH will be seven: This statement is incorrect for the following reasons:

   • When equal concentrations of a weak acid (CH₃COOH) and a strong base (NaOH) are mixed, the resulting solution may not have a pH of exactly 7. Due to the presence of acetate ions (from CH₃COO^-) which are basic, the solution is usually slightly basic, with a pH slightly greater than 7.
   • The complete neutralization of the acetic acid does not guarantee a neutral pH because of the salt hydrolysis effect.

3. pH of dilute and hot H₂SO₄ is more than concentrate and cold H₂SO₄: This statement is true. The concentration and temperature affect acid strength and dissociation. A concentrated solution of H₂SO₄ will have a lower pH (more acidic) compared to a diluted one. Moreover, heating usually increases dissociation to some extent but isn't enough to make dilute solutions more acidic than concentrated ones.

4. Mixing solution of CH₃COOH and HCl, pH will be less than 7: This statement is true. Both CH₃COOH (acetic acid) and HCl (hydrochloric acid) are acids, and their combination results in an acidic solution with a pH less than 7.

Conclusion: The incorrect statement about pH and H^+ is: Adding 1N,1N solⁿ of CH₃COOH and NaOH pH will be seven.