1.

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

Answer»

m - chlorobenzoic acid `(pK_(a) = 3.98)`
p - chlorocinnamic acid `(pK_(a) = 4.41)`
2, 5-dihydroxy benzoic acid `(pK_(a) = 2.97)`
Acetoacetic acid `(pK_(a) = 3.58)`

Solution :`pH = pK_(a) + log.(["SALT"])/(["Acid"])`. For HIGHEST buffer CAPACITY `(["Salt"])/(["Acid"]) ~~ 1`
`pH = pK_(a) + log_(10)1`
`pH = pK_(a)`
So, `pK_(a)` should be 3.58.


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