My question is found in the analysis section. Thanks to all who can help
Lab: Determining Ka of Acetic Acid
Purpose: The purpose of this experiment is to determine the molar concentration of a sample of acetic acid and to calculate its Ka.
Materials:
phenolphthalein
125 mL Erlenmeyer flask
25 mL pipet and bulb
pH metre
acetic acid solution
burette
sodium hydroxide solution
2x150 mL beaker
Procedure
1. Recorde the molar concentraiton of the NaOH solution
2.Produce a table to record your data. It should have one column for volume of NaOH added and one column for pH
3. Obtain 50 mL of acetic acid and place it into a beaker
4.Place 50.0 mL of NaOH into the burette.
5. Pipet 25.0 mL of acetic acid into the Erlenmeyer flask. Add 2 drops of phenolphthalien to the acid.
6. Record the initial pH of the solution
7. Add 1.00 mL of NaOH from the burette to the Erlynmeyer until the pH reaches 5.00. Record the volume of two decimal places. Measure the pH of the solution each time you add NaOH.
8. Above pH = 5.00, add NaOH in 0.10 or 0.20 mL portions. Record the volume at which the phenophthalein turns pink.
9. Continue to add NaOH until the pH reaches 11.00. Above pH = 11.00, add 0.10 mL portions until the pH reaches 12.00.
Here are my results:
NaOH (ml) pH
0.00 2.58
1.00 3.57
2.00 3.89
3.00 4.12
4.00 4.29
5.00 4.44
6.00 4.58
7.00 4.73
8.00 4.88
9.00 5.04
9.20 5.09
9.40 5.12
9.60 5.17
9.80 5.21
10.00 5.26
10.20 5.32
10.40 5.39
10.60 5.42
10.80 5.52
11.00 5.61
11.20 5.74
11.40 6.11
11.60 6.26
11.80 6.50
12.00 10.66
12.20 11.19
12.30 11.32
12.40 11.40
12.50 11.55
12.60 11.62
12.70 11.69
12.80 11.74
12.90 11.78
13.20 11.82
13.40 11.85
13.60 11.89
14.10 11.95
15.00 12.00
Analysis:
Write a chemical equation for the neutralization reaction you observed.
CH3COOH + NaOH --> NaCH3COO + H2O
How would I calculate the molar concentrtion of the acetic acid after plotting a graph of my data?
what is the x axis and y axis of your data?
The graph will have an S shaped curve somehting like this:
    &nsbp     &nsbp--------
&nsbp     &nsbp   /
        /
      /
----------------/
Determine the mid-point of the curve in the middle of the sharp vertical portion (around pH 8-10) and read the mL there.
Then mols NaOH = L x M
That will be the mols acetic acid.
mols acetic /volume used for the titration = molarity.
I hope the attempt at a titration curve turns out ok. After you have plotted the date perhaps what I have drawn will make more sense.
X axis - Volume of NaOH(mL)
Y axis - pH
Perhaps this one will look a little better.
      &nsbp &nsbp --------
          /
          |
          |
&mbs[         |
-----------------------------/
Perhaps this one will look a little better. I quit if this one isn't better.
          --------
         /
          | |
          | |
          |
-----------------------------/
I just can't make it look right. Sorry.
Don't worry about it :)
I think I got it right
Determine the mid-point of the curve in the middle of the sharp vertical portion (around pH 8-10) and read the mL there
Isnt the sharp vertical portion around pH 12?