Ka of acetic acid

background [prelab (15 points) due at the beginning of lab]

describe how to determine Ka using data from the titration curve based on the

pH of the acetic acid solution prior to titration using the definition of Ka

pH at 1/2 equilivalence point using the Henderson - Hasselbalch equation

sketch a data table for this lab containing entries for all required experimental measurements (i.e. review purpose & content of lab report)

purpose

assess the accuracy of the determination of Ka of acetic acid using the above methods

identify the "buffer region" in the titration curve

compare the pH at the equivalence point: calculated value versus experimental value

materials

vinegar (i.e. acetic acid; ~30 mL); NaOH (~ 0.5 M)

beaker; buret; ring stand with buret clamp; pH meter

methods / data analysis [delegate lab work]

student design, includes student preparation of a known [NaOH] solution

refer to prior lab in the calibration of the pH probe [before lab !]

 

Content of the lab report [35 points]

data analysis   (25 points)

titration curve & a plot of its first derivative

determination of the Ka of acetic acid using the above 2 methods - based on your group's data (show your work)

calculate the pH at equivalence point based on the concentration & volume of the acetic acid solution

statistical analysis (include interpretation of p-value; use appropriate statistical test(s); see purpose; there's more than one method to analyze the data)

discussion (10 points)

based on the statistical analysis, discuss the accuracy in each method to determine the Ka of acetic acid

referring to the titration curve, define the term "buffer capacity" & "buffer region"

 

resources:

lab activity source (examples):  site 1  & site 2 [access 4 / 2009]