Post a picture of your titration setup, and a photo of your analyte at the equivalence point. Write a short summary of your procedure. Calculate the percent ionization of vinegar and describe why it is such a low number.
Following the directions on the lab sheet, we filled up the burette to the zero point with the 0.25 M NaOH base. We added vinegar to the flask along with distilled water and four drops of phenolphthalein. After securing the burette to the stand and placing the flask on the hot place, we started the magnetic stir of the mixture. Slowly, we opened the valve of the burette to release the NaOH base. Once the drops started to make more noticeably pink streaks in the mixture and it took longer to return to the clear color, we knew the equivalence point was approaching. At that point, we switched to a drop by drop method so that the mixture would not pass the equivalence point and become bright pink. After the drop that caused the mixture to turn light pink, we took the tip of the burette out of the opening of the flask and took the photos below. We also repeated this procedure for a second trial, knowing the relative amount of NaOH base that would be needed.
Trial one:
Volume of NaOH used = 25.0 mL
pH of vinegar = 2.4
Molarity of acid = 0.86 M
Volume of acid = 0.00725 L
Molarity of base = 0.25 M
Volume of base = 0.0250 L
Trial two:
Volume of NaOH used = 25.5 mL
pH of vinegar = 2.4
Molarity of acid = 0.98 M
Volume of acid = 0.00720 L
Molarity of base = 0.25 M
Volume of base = 0.0255 L
Average concentration of vinegar = 0.875 M
[H3O+] = 10^-2.4 = 0.0040
Percent ionization = 0.46%
The percent ionization is such a low number because it does not have the properties that would allow it to break into ions. Strong bases have a 100% ionization because the acid and base completely ionize. Since vinegar is a weak acid, it does not completely break apart into ions.
Setup:
Following the directions on the lab sheet, we filled up the burette to the zero point with the 0.25 M NaOH base. We added vinegar to the flask along with distilled water and four drops of phenolphthalein. After securing the burette to the stand and placing the flask on the hot place, we started the magnetic stir of the mixture. Slowly, we opened the valve of the burette to release the NaOH base. Once the drops started to make more noticeably pink streaks in the mixture and it took longer to return to the clear color, we knew the equivalence point was approaching. At that point, we switched to a drop by drop method so that the mixture would not pass the equivalence point and become bright pink. After the drop that caused the mixture to turn light pink, we took the tip of the burette out of the opening of the flask and took the photos below. We also repeated this procedure for a second trial, knowing the relative amount of NaOH base that would be needed.
Trial one:
Ms. Kapinos looking pleased with our titration success:
Trial two:
Volume of NaOH used = 25.0 mL
pH of vinegar = 2.4
Molarity of acid = 0.86 M
Volume of acid = 0.00725 L
Molarity of base = 0.25 M
Volume of base = 0.0250 L
Trial two:
Volume of NaOH used = 25.5 mL
pH of vinegar = 2.4
Molarity of acid = 0.98 M
Volume of acid = 0.00720 L
Molarity of base = 0.25 M
Volume of base = 0.0255 L
Average concentration of vinegar = 0.875 M
[H3O+] = 10^-2.4 = 0.0040
Percent ionization = 0.46%
The percent ionization is such a low number because it does not have the properties that would allow it to break into ions. Strong bases have a 100% ionization because the acid and base completely ionize. Since vinegar is a weak acid, it does not completely break apart into ions.
pic creds to Ms. Kapinos #candid:
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