# CHEMISTRY FOR DR. BOB or anyone else

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A hypothetical weak acid HA, was combined with NaOH in the following proportions: 0.20 mol HA, 0.08 mol NaOH. The mixture was then diluted to a total volume of 1L, and the pH measured.

(a) If pH=4.80, what is the pKa of the acid

(b) how many additional moles of NaOH should be added to the solution to increase the pH to 5.00

Sorry bout that. I didn't notice part b.
Assuming not all of the HA is neutralized and that you still have a buffered solution,
Use the Henderson-Hasselbalch equation.
pH = pKa + log [(base)/(acid)].
OR just use the simple Ka expression you used for part a, plug in (H^+) equivalent to pH = 5.00.

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