Titration. by

First! Make sure you know you strong acids and bases.

daalvarezlabrada001 — 2022-07-25 16:59:27 UTC

daalvarezlabrada001 — 2022-07-25 17:01:10 UTC

Now let's get to the problem!

daalvarezlabrada001 — 2022-07-25 17:04:36 UTC

Remember to not get scared! sometimes short is not better!

daalvarezlabrada001 — 2022-07-25 17:06:36 UTC

Calculate the Ph in the titration of 40 ml of 0.150M acetic acid by sodium hydroxide after the addition to the acid solution of:
A) 15 ml of 0.150M NaOH
B) 40 ml of 0.150M NaOH
C) 60 ml of 0.150M NaOH

Determine what you are working with.

daalvarezlabrada001 — 2022-07-25 17:09:02 UTC

Determine with what you are working

CH3COOH <-> H^+ +CH3COO^- = weak acid
NaOH -> Na^+ + OH^- = second group (Strong Base)
@ 150 M
a) 15ml < 40ml = before (buffer)
b) 40ml = 40ml = at (salt)
c) 60 ml > 40 ml = after (excess)

A) 15 ml

daalvarezlabrada001 — 2022-07-25 17:10:14 UTC

Step 1) Find moles for acid and bases
NaOH= 15ml x 0.150M = 2.25 mmol
CH3COOH= 40ml x 0.150m = 6 mmol
* Decide whether it's easier to work with ml and mmol or L and Mol.
Print or have in hand your Ka table

Remember to choose the correct pH formula.

daalvarezlabrada001 — 2022-07-25 17:15:18 UTC

daalvarezlabrada001 — 2022-07-25 17:18:34 UTC

daalvarezlabrada001 — 2022-07-25 17:25:26 UTC

Before equivalence.

daalvarezlabrada001 — 2022-07-25 17:31:38 UTC

Treat like a buffer.
- Calculate moles of both acid and base.
- Treat problem just like a buffer problem.
- Use Henderson- Hasselbalch to calculate pH.

At equivalence.

daalvarezlabrada001 — 2022-07-25 17:35:34 UTC

Treat like a salt problem.
- Calculate moles of acid/base in the flask.
- Calculate [M] using total volume now in flask.
- Salt with go trough hydrolysis.
- Use ion that controls pH to set up the ice table.
- Calculate [M].
- Calculate the conjugate Ka or Kb.
- Calculate pH.

After equivalence.

daalvarezlabrada001 — 2022-07-25 17:38:15 UTC

Treat like an excess problem.
- Calculate moles of acid/base.
- Subtract moles.
- Calculate [M] of excess moles using total volume in L.
- Calculate pH.

daalvarezlabrada001 — 2022-07-25 18:12:16 UTC

The trick to master titrations!

daalvarezlabrada001 — 2022-07-25 18:20:33 UTC

daalvarezlabrada001 — 2022-07-25 22:11:42 UTC

Choosing the wrong pH formula will take you all the way back so be really careful and determine what you have and label it!

daalvarezlabrada001 — 2022-07-25 22:23:21 UTC

Overall:

daalvarezlabrada001 — 2022-07-25 22:26:47 UTC

1- You will always need to determine the moles of acid and base.
From there it will much easier to determine the kind of problem and you will know how to treat it.