20 ml of CH\(_3\)COOH solution is neutralised by 28.08 ml of NaOH. In the 20 ml of same solution 14.04 ml of same NaOH solution is poured, then pH of resultant solution will be: (pKa of CH\(_3\)COOH = 4.75)

Question

Consider the following compounds:
(i) CH₃CH₂Br
(ii) CH₃CH₂CH₂Br
(iii) CH₃CH₂CH₂CH₂Br
Arrange the compounds in the increasing order of their boiling points.

Answer 1

Step 1: Understanding the Concept:
When a weak acid is partially neutralized by a strong base, it forms a buffer solution consisting of the weak acid and its conjugate base (salt). The pH is determined by the ratio of salt to acid concentrations.

Step 2: Key Formula or Approach:
Henderson-Hasselbalch Equation: \[ \text{pH} = pK_a + \log \frac{[\text{Salt}]}{[\text{Acid}]} \]

Step 3: Detailed Explanation:
The volume of \( \text{NaOH} \) required for complete neutralization is \( 28.08 \) ml.
When \( 14.04 \) ml of \( \text{NaOH} \) is added, exactly half of the weak acid has been converted to its salt.
\[ \text{Moles of salt formed} = \text{Moles of acid remaining} \] Therefore, the ratio \( \frac{[\text{Salt}]}{[\text{Acid}]} = 1 \).
Substituting into the equation: \[ \text{pH} = 4.75 + \log(1) \] Since \( \log(1) = 0 \): \[ \text{pH} = 4.75 \]

Step 4: Final Answer:
The pH of the resultant solution is 4.75.

20 ml of CH\(_3\)COOH solution is neutralised by 28.08 ml of NaOH. In the 20 ml of same solution 14.04 ml of same NaOH solution is poured, then pH of resultant solution will be: (pKa of CH\(_3\)COOH = 4.75)

The Correct Option is A

Solution and Explanation

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