Organic Chemistry Lab Report

Name:Exp #
Date:
Lab Partner
Title: Acid- base extraction
1. Abstract and Purpose: (2 point).
In this laboratory experiment, a mixture of three compounds, benzoic acid, 4-nitroaniline, and
naphthalene will be separated using the liquid-liquid acid-base extraction technique. In subsequent
steps, an organic solvent is used to dissolve the mixture, and then the base was extracted using an
acid aqueous solution. Then, the acid was extracted using an aqueous basic solution and the
remaining neutral compound was isolated by evaporating the organic solvent.
2. Balanced equation: (2 point)
The only chemical reactions involved are acid-base reactions. However, no new compounds will
be formed.
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Exp #
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3. Reagent Table (Add more rows when needed) (3 points)
Name
M.W.
(g/mol)
Density
*
(g/mL)
M.P.*
(°C)
B.P.*
(°C)
Benzoic acid
Naphthalene
4-nitroaniline
122.12
128.17
138.12
84.93
1.325
146-149
80-82
146-149
–
–
Dichloromethane
39.840
Amount
(grams
or mL)
1.5 g
mixture
–
Moles
Hazards/Precautions
–
Irritant
Irritant, volatile
Irritant
Carcinogen, irritant,
flammable, volatile
4. Calculations: Shown each calculation for moles of reagents, limiting reagent, theoretical yield
and percent yield. (4 points)
There is no theoretical yield given that there are no chemical reactions leading to new products.
The mixture of 1.5 g contains all three of the compounds in roughly equal masses, no calculations
of moles are needed.
The theoretical yield of the sum of the masses of the three recovered compounds should be 1.5 g.
5. Procedure, Observations and Data
Procedure (4 point)
•
Dissolve 1.5 g of the mixture sample in 40
mL of dichloromethane in a separatory
funnel
•
Add 15 mL 3M HCl, shake and vent and
decant the bottom organic layer to a beaker
•
Pour the top aqueous layer in a separated
beaker
Observations and Lab Data (4 point)
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•
The organic layer is put again in the funnel
and the extraction repeated two more times.
•
The organic layer is extracted two times with
a similar procedure with aqueous 3M NaOH
and the solution put in a separated beaker.
•
The acid aqueous solution is neutralized until
the solid appears, filtered and recrystallized
to obtained pure base.
•
The basic aqueous solution is neutralized
until the solid appears, filtered and
recrystallized to obtained the pure acid.
•
The organic layer form the funnel is dried in
a beaker with sodium sulfate, filtered and the
solvent evaporated to obtained the pure
neutral compound.
6. Conclusions and discussions (4 points)
8. Answers to Post-lab questions (2 points)
I. Benzoic acid is soluble in diethyl ether but not water; however, benzoic acid
is extracted from diethyl ether with aqueous sodium hydroxide.
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1. Complete the acid-base reaction below by writing the products of the reaction and
label the acid, the base, conjugate acid, and conjugate base.
2. Indicate the solubility of benzoic acid and its conjugate base in diethyl ether and in
water.
II. Aniline, an amine, is soluble in diethyl ether but not water; however, aniline is
extracted from diethyl ether with aqueous hydrochloric acid.
1. Complete the acid-base reaction below by writing the products of the reaction and
label the acid, the base, conjugate acid, and conjugate base.
2. Indicate the solubility of aniline and its conjugate acid in diethyl ether and in water.
9. References: (1 point)
10. Image of your lab notebook. (3 point)
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I reserve the right to modify points on this template at any time.
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