Reference no: EM131924340
Lab - The Titration of Vinegar
PRE-LAB QUESTIONS
1. Why are you using phenolphthalein as an indicator?
2. Estimate the volume reading for the burette depicted in Figure 10.1.
3. Distinguish between the endpoint and equivalence point.
4. If 12.66 mL of 0.250 M NaOH solution is used in a titration how many moles of OH- were added? How many moles of H+ could be neutralized with this amount of hydroxide?
POST-LAB QUESTIONS -
1. Discuss the main sources of error in this experiment.
2. Sally Chemist is attempting to determine the mass % of acetic acid in vinegar using the experimental procedure described above. Below is an excerpt from her lab book:
a. Prepared vinegar analyte
25.0 mL vinegar
Mass of vinegar = 25.20 g
Added 75.0 mL H2O
Added 2 drops phenolphthalein
Temperature: 27.0oC
Manufacturer's mass % acetic acid = 3.5%
b. Prepared burette
Cleaned and dried burette
Filled with standardized NaOH solution 0.201 M
c. Titration
Initial burette reading: 5.12 mL
Final burette reading: 78.67 mL
Solution is light pink
Room temp unchanged.
i. What is the density of her vinegar sample?
ii. Use the manufacturers reported mass % acetic acid to estimate how many moles of acetic acid are present in her analyte.
iii. Use your result from ii to estimate how many mL of standardized NaOH solution she will need to reach the equivalence point.
iv. Use Sally's data to calculate the molarity of acetic acid in her vinegar sample.
v. Use the results from iv to calculate the mass % of acetic acid in Sally's vinegar sample.
vi. How would the following experimental errors affect Sally's experimental result?
DATA ANALYSIS -
1. Calculate the following for each trial and average the values:
a. Moles of NaOH used
b. Moles of acetic acid reacted
c. Mass in grams of acetic acid reacted
d. Molar concentration of acetic acid
e. Mass % of acetic acid
2. Calculate the percent error between your average experimental value of the mass % of acetic acid in vinegar and the manufacturer's reported mass % of acetic acid in vinegar.
Attachment:- Assignment Files.rar