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# pH during titration prcoess

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Calculate Titration. See attached file for full problem description.

19. Calculate the pH at 0, 10.0, 25.0, 50.0, and 60.0 mL of titrant in the titration of 25.0 mL of 0.200 M HA with 0.100 M NaOH. Ka = 2.0 * 10^-5.

20. Calculate the pH at 0, 10.0, 25.0, 50.0, and 60.0 mL of titrant in the titration of 50.0 mL of 0.100 M NH3 with 0.100 M HCl.

https://brainmass.com/chemistry/titration/ph-during-titration-prcoess-105567

#### Solution Preview

Calculate the pH at 0, 10.0, 25.0, 50.0 and 60.0 mL titrant in the titration of 25.0 mL of 0.200M HA with 0.100M NaOH. (Ka for HA is 2 x 10^-5).

(a) Addition of 0.0 mL base NaOH.

Initial Concentration 0.200 0 0
Equilibrium, M 0.200-x x x
Assume at the equilibrium is x M.
Then
Since the concentration of HAis 0.300M ,which is much greater than 100Ka, then x at the denominator can be neglected.
So

Or
M.

(b) Addition of 10 mL of NaOH

Initial mmol 5.00 1.00 0 0
Final, 4.00 0 1.00 1.00
The initial moles of is
And NaOH is
So after reaching the equilibrium, there is still 4 mmol of left.
This is a buffer solution,
, where V is the final volume of the mixture in mL.

Or you can deduct it by yourself as followings
Assume at the equilibrium is x M.

Initial 4.00 ...

#### Solution Summary

The solution shows how to calculate the pH during the titration process when different amount of titrant added. The solution is detailed and well presented.

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