Phenylacetic acid (HC8H7O2) is one of the substances that accumulates in the blood of persons with phenylketonuria, an inherited disorder that can cause mental retardation and even death. A 0.033 M solution of HC8H7O2 is found to have a pH of 2.9. ?

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What is the pKa of HC8H7O2?

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Answer 1 · 2018-03-27T21:19:39

4.3

$sf(pH=1/2[pK_a-loga])$

Where $sf(a)$ is the concentration of the weak acid.

$:.$ $sf(2.9=1/2[pK_a-log(0.033)])$

$sf(2.9=1/2 pK_a-1/2(-1.481))$

$sf(2.9=1/2pK_a+0.7407)$

$sf(1/2pK_a=2.159)$

$sf(pK_a=4.32)$