A weak acid with an initial pH of 3.2 was titrated with a strong base. 15 mL of 0.1 M NaOH was added to the acid to reach the equivalence point at a pH of 8.6. What would you expect the approximate pH of the analyte to be after the first 5 mL of 0.1 M NaOH was added?

A. 5.1
B. 7.2
C. 3.4
D. 8.6

Question

A weak acid with an initial pH of 3.2 was titrated with a strong base. 15 mL of 0.1 M NaOH was added to the acid to reach the equivalence point at a pH of 8.6. What would you expect the approximate pH of the analyte to be after the first 5 mL of 0.1 M NaOH was added?

 		A.	5.1
 		B.	7.2
 		C.	3.4
 		D.	8.6

photon336 · Answer

definitely not 8.6.. would be <8.6 for sure.

cuanchi · Answer

I will said between 3.2 and 8.6

photon336 · Answer

@cuanchi is there a formula for this, because we don't know anything about the pKa. i would guess it's either 5.1 or 7.2

cuanchi · Answer

I am trying to figure out

photon336 · Answer

pH = pKA so at that point half the acid is gone.

cuanchi · Answer

we can not calculate the Ka because we don't have the initial volume of the acid, neither the final volume after the titration.
We can calculate the moles but not the concentrations

cuanchi · Answer

what is your logical thinking about the problem?

cuanchi · Answer

did you read the book?

cuanchi · Answer

why do you think is B?

photon336 · Answer

I'm curious to know how to get the answer for this

cuanchi · Answer

@vera_ewing did you find the correct answer yet?