Experiment L RESULTS Name and Mail Box Number: Sienna bsouto Lab Partner(s) Heat

Question

Experiment L RESULTS Name and Mail Box Number: Sienna bsouto Lab Partner(s) Heatha Malan Part A: Strong Acids Versus Weak Acids tual Theoretical Theoretical Measured Measured Measured Step inal H l Ionization Acid LacidL Step 1 HCl Step 2 HAc How do your theoretical pH values agree with your measured pH values? Our br eo ren cues are to inuu close to our measu (pH values wicnin .5 Complete the following before making the measurements in Step 3 and Step 4 of Part A. Calculated [HCl] after dilution Calculated [HAc] after dilution: Prediction: Dilution will cause the pH to do what? go towards Tulintinnt Which acid solution will be more greatly affected by dilution

Explanation / Answer

Note that...

The theoretical value for [H+] from HCl, will be 100% dissociation so 0.094 M of HCl = 0.094 M

pH = -log(0.094) = 1.026

For theoretical [H+] from Acetic acid, we need:

For HAc = Acetic acid, you will expect:

Ka = [H+][Ac-]/[HAc

1.8*109^-5 = x*x/(0.02-x)

x = [H+] = 5.91*10^-4

pH = -log( 5.91*10^-4) = 3.228

Note that the measured [H+] is the one you will MEASURE in the lab with either a pH-meter or a conductivity meter

this can't be calculated, by definition, it must be measured.

Typically, the "real" value is then compared with tthe "theoretical" value

Finally

the measured % ionization is obtained via

% ionization = [H+]/M*100%

for HCl:

% ionization = (0.094)/(0.094) *100% = 100% (as expected

for acetic acid:

x = [H+] = 5.91*10^-4

so

%ioniztion = (5.91*10^-4) / 0.02 * 100 = 2.955 %

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