Chemistry 156 - 2022
D-4 Questions
Answer the following questions in the spaces provided. Your answers to these questions
are due by the end of day (11:59 p.m.) on the day of your Discussion Meeting. Do not
answer these questions in your laboratory notebook.
Please make your answers to these questions brief (a few sentences, maximum, in most
cases, will suffice!)
I. Ester Extraction
1. Write a stepwise plan for the extraction of your ester. (You may choose to attach a photo of
your lab notebook here, instead of directly writing this in)
2. (a) Complete the table below and determine the percentage yield of the
4-Amino-3-nitrobenzoic acid methyl ester in the experiment. Show your calculations below the
table.
Reagents/ Product
Molecular mass/ g mol-1
Quantity
4-amino-3-nitrobenzoic acid
(C7H6N2O4)
Methanol, MeOH
182.03
0.150 g
----
10 mL
Concentrated sulfuric acid,
H2SO4
4-Amino-3-nitrobenzoic acid
methyl ester
---
3 drops
0.077 g
# of moles
---
(b) (i) Tabulate the major IR peaks (stretches) for your carboxylic acid.
Assigned Carboxylic acid Name :
Observed Frequency
(cm-1)
Expected Frequency*
(cm-1)
Functional
group
Intensity of peaks
Intensity: weak, w; strong, s; medium, m; br, broad
(ii)Identify at least two peaks in your table above that would help you distinguish your product
ester from the carboxylic acid and briefly explain how you expect the two spectra to differ.
II. Extraction Technique Development
3. (a) Complete the table below with the densities of the solvents. Designate as polar or
non-polar.
Solvent
Water
Ethyl acetate
(b)
Density at room temp. (g mL-1)
Polar or non-polar
In what solvent(s) is carotene soluble:
_____________________________________________________________________
List your observations from this extraction (consider color of layers, polarity, location of
aqueous and organic layers).
(c) In what solvent(s) is Coomassie Brilliant Blue soluble?
List your observations from this extraction (consider color of layers/intensity, polarity, location
of aqueous and organic layers)
(d) In what solvent(s) is the iodine (I2) soluble? (consider whether iodine is polar or non-polar)
___________________________________________________________________________
List your observations from this extraction (consider color of layers, polarity, location of
aqueous and organic layers, partitioning between phases)
(e) Is the glass of your separatory funnel hydrophobic (nonpolar) or hydrophilic (polar)? Provide
a reason to support your answer.
(f) Identify at least one lesson you’ve learned about correctly carrying out a liquid-liquid
extraction.