Question

The name of the experiment is Preparation of Synthetic Banana oil. The name of the author of the book is John Lehma. chapter 5.

(incase needed, we used 20.o mmol of isopentyl and 40 mmol of glacial acetic acid)

In the ''understanding experiment'' section, it was stated that the reaction of an equimolar mixture of isopentyl alcohol and acetic acid will produce, at most, 67% of the theoretical amount of isopentyl acetate. verify this with an equilibrium constant calculation, using K = 4.2 . b) compare this with the corresponding percentage for the conditions used in this experiment (see exercise 1 ) Please explain well.

Exercise 1 is also found in the book, however the ammount of chemicals used in the experiment are stated above. Thank you.

Answer 1

The problem I have with this setup is that it doesn't account for water. Water doesn't normally go in an ICE table, but in this case it is a product. Also, the lab book (Lehman, exp 5) says the theoretical yield should be 67% with equimolar concentrations. I can't get 67% unless I put water in the ICE table. Here's how I'd change your math:

Isopentyl Alcohol + Acetic Acid   Isopentyl Acetate

starting moles starting moles 0
-x -x +x
starting moles - x starting moles - x +x


So we have

4.2 = x²/((moles_{isopentyl alcohol} - x)*(moles_{acetic acid} - x))

4.2 = x² - 1.87614x + 0.186921
x² - 1.87614x + 0.186921 = 0

x = 0.1272
x = 0.4590

Theoretical yield = 84.8%

(not having much idea) but to get you started, use acid + alcohol <--> ester + water reaction

you'll need isobutyl alcohol and propinoic acid also conc sulfuric to get equilibrium to go to the right.

Product distils at 66.5C so select your range from that.