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Charra [1.4K]
3 years ago
8

A buffer solution is made using a weak acid, HA. If the pH of the buffer is 9 and the ratio of A– to HA is 100, what is the pKa

of HA?
Chemistry
1 answer:
sdas [7]3 years ago
3 0
To calculate the pKa of the weak acid, we use the Henderson-Hasselbalch equation. It is expressed as pH = pKa - log [HA]/[A-]. This equation takes into account the concentration of the substance that does not dissociates into ions since it is a weak acid. We caculate as follows:

pH = pKa - log [HA]/[A-]
9 = pKa - log 1/100
pKa = 7
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