Question

The \[pH\] of a solution which is \[0.1M\] sodium acetate and \[0.01M\] acetic acid (\[p{K_a} = 4.74\]) would be:
A. \[4.2\]
B. \[5.1\]
C. \[5.74\]
D. None of these

Answer 1

Hint: This inquiry is tackled by utilizing the condition of \[pH\] for buffer solutions and for example known as the Henderson-Hasselbalch condition. This condition is utilized for the figuring of \[pH\] of the buffer solutions. Here we can utilize the equation of pH for the acidic buffer.
\[pH\; = p{K_a} + log\dfrac{{\left[ {salt} \right]}}{{\left[ {acid} \right]}}\] (Henderson-Hasselbalch equation)

Complete step by step answer:
Here, we can begin with the Henderson-Hasselbalch condition. As we have known from the question that salt is acetate acid and acid is acetic acid.
This is an acidic buffer solution, as per this we can utilize the condition.
\[pH\; = p{K_a} + log\dfrac{{\left[ {salt} \right]}}{{\left[ {acid} \right]}}\]
Presently, we have the estimations of \[p{K_a}{\text{ }} = {\text{ }}4.74\]and concentration of sodium acetate and acetic acid is \[0.1M\] and \[0.01M\] respectively. At that point by utilizing these values we can find out the \[pH\] of the given question.
Consequently, placing the above values in our condition we will get;
\[pH = p{K_a} + log\dfrac{{\left[ {C{H_3}COONa} \right]}}{{\left[ {C{H_3}COOH} \right]}}\]
\[pH = 4.74 + log\dfrac{{0.1}}{{0.01}}\]
\[pH = 4.74 + 1\]
\[pH = 5.74\]
Subsequently, the \[pH\] of the buffer solution is \[5.74\].

So, the correct answer is Option C.

Note: Buffer: The buffer solution is the solution which keeps up its pH even at the expansion of the acid or base. The buffers are of two kinds\[1\]) Acidic buffer and\[2\]) Basic buffer. A combination of acidic acid and sodium acetic acid derivation go about as a buffer solution and since in this response sodium hydroxide is responding with acidic acid delivering sodium acetic acid derivation. In this manner, the general solution is going about as a buffer solution as when acidic acid and sodium acetic acid derivation are available in a similar medium, they go about as buffers in one another's essence.
In the above issue the combination is going about as a buffer solution. Buffer solution contains weak acid and its form base or powerless base and its form acid. In the above inquiry sodium acetic acid derivation is a feeble fundamental salt while acidic acid is a form acid of it. So, it goes about as a decent buffer for feeble acidic solutions. This can be tackled by the Henderson HasselBalch condition which is \[pH = p{K_a} + log\dfrac{{salt}}{{acid}}\].
we have given the acid buffer with its \[p{K_a}\] and its focus esteems. When settling this kind of inquiry bring one thing into mind: what sort of buffer is given to us acid or essential. Since as per that we need to utilize the formula.