A physician wishes to prepare a buffer solution at pH= 3.58 that efficiently resist changes in pH yet contains only small concentration of the buffering agents. Which one of the following weak acid together with its sodium salt would be best to use?

Question

A physician wishes to prepare a buffer solution at pH= 3.58 that efficiently resist changes in pH yet contains only small concentration of the buffering agents. Which one of the following weak acid together with its sodium salt would be best to use? (A) m-chlorobenzoic acid (pKa = 3.98 )  (B) p-chlorocinnamic acid ( pKa = 4.41)  (C) 2, 5-dihydroxy benzoic acid (pKa = 2.97 )  (D) Acetoacetic acid (pKa = 3.58 )

Tardigrade Admin · Accepted Answer

By the use of Henderson's equation pH=p Ka+ log 10 ([ text salt ]/[ textacid]) When, [ salt ]=[ acid ] ∴ p H=p Ka ∵ p Ka=3.58, thus at this state p H=3.58 So, acetoacetic acid (p Ka=3.58) is best to use

Q. A physician wishes to prepare a buffer solution at $p H = 3.58$ that efficiently resist changes in $p H$ yet contains only small concentration of the buffering agents.
Which one of the following weak acid together with its sodium salt would be best to use?

m-chlorobenzoic acid $(p K_{a} = 3.98)$

p-chlorocinnamic acid $(p K_{a} = 4.41)$

2, 5-dihydroxy benzoic acid $(p K_{a} = 2.97)$

Acetoacetic acid $(p K_{a} = 3.58)$

By the use of Henderson's equation
$p H = p K_{a} + lo g_{10} \frac{[ salt ]}{[ acid]}$
When, $[$ salt $] = [$ acid $]$
$∴ p H = p K_{a}$
$∵ p K_{a} = 3.58,$ thus at this state
$p H = 3.58$
So, acetoacetic acid $(p K_{a} = 3.58)$ is best to use

Q. A physician wishes to prepare a buffer solution at pH=3.58 that efficiently resist changes in pH yet contains only small concentration of the buffering agents. Which one of the following weak acid together with its sodium salt would be best to use?

m-chlorobenzoic acid (pKa​=3.98)

p-chlorocinnamic acid (pKa​=4.41)

2, 5-dihydroxy benzoic acid (pKa​=2.97)

Acetoacetic acid (pKa​=3.58)