CHEM 6AL Experiment #1: Solubility and Melting Point Lab Report
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CHEM 6al
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CHEM 6al
CHEM 6AL Experiment #1: Solubility and Melting Point
Introduction
In this experiment, the solubility of organic compounds in various
solvents and the melting point of organic compounds were experimentally tested.
This experiment was conducted to familiarize the experimenters with basic
techniq...
chem 6al experiment 1 solubility and melting point lab report
chem 6al experiment 1 solubility and melting point introduction in this experiment
the solubility of organic compounds in various solve
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CHEM 6AL Experiment #1: Solubility and Melting Point
Introduction
In this experiment, the solubility of organic compounds in various
solvents and the melting point of organic compounds were experimentally tested.
This experiment was conducted to familiarize the experimenters with basic
techniques used in the organic chemistry laboratory, as well as to cement an
understanding of the effect intermolecular forces have on the physical
properties of organic compounds. More specifically, the interplay between non-
polar carbon-chain elements of organic compounds and polar functional groups on
the compounds were tested. Both polar and non-polar solvents were used in
combination with these compounds.
Discussion
In the first part of this experiment, the solubility of Benzophenone,
malonic acid, and biphenyl were tested for solubility in water, methanol, and
hexane. Benzophenone was predicted to be soluble in water, partially soluble in
methanol, and insoluble in hexane, but was found to be insoluble in water and
hexane, and soluble in methanol. Its insolubility in hexane was likely an error.
Malonic acid, being extremely polar, was predicted to be soluble in water and
methanol, and insoluble in hexane, which was confirmed experimentally. Biphenyl
was predicted to be insoluble in all three solvents, and the experiment
confirmed these except for methanol, in which is was soluble. The results for
hexane and methanol are likely erroneous.
In the second part of the experiment, the solubility of three alcohols (1-
octanol, 1-butanol, and methanol) were tested in water and hexane. The results
1-octanol and methanol lined up with the predictions, with the former being
insoluble in water and soluble in hexane, and the latter being soluble in water
and insoluble in hexane. 1-butanol was predicted to be partially soluble in both
solvents, but was found to be insoluble in water and soluble in hexane.
In the third part of the experiment, the miscibility of various compounds
were tested together in five trials. Water and ethanol, as well as hexane and
methylene chloride were predicted to be miscible (respectively), and these
predictions were confirmed experimentally. However, water and diethyl ether, as
well as water and methylene chloride were predicted to be miscible, but were
found to be immiscible. Water and hexane, being very polar and very non-polar
(respectively), were predicted to be immiscible and confirmed experimentally.
In the fourth part of the experiment, the solubility of benzoic acid and
ethyl-4-aminobenzoate was tested in water, 1.0M NaOH, and 1.0M HCl. Benzoic acid
was predicted to be insoluble in HCL, soluble in NaOH, and partially soluble in
water. These findings were confirmed, except for a partial solubility in
hydrochloric acid, which was likely erroneous. Ethyl-4-aminobenzoate was
predicted to be insoluble in NaOH and soluble in HCl, and these predictions were
confirmed, but was found to be insoluble in water contrary to the prediction of
partial solubility. When 6.0M HCL was added to the solution of benzoic acid and
NaOH, the benzoic acid re-precipitated due to its re-protonation. When 6.0M NaOH
was added to the solution of ethyl-4-aminobenzoate and HCl, the same occurred.
In general, the results obtained during the first four parts of the
experiment (barring a couple likely erroneous results) are consistent with the
notion that “like dissolves like.” In more technical terms, solutes with polar
functional groups were found to be more soluble in polar solvents, while solutes
with significant non-polar chains were found to be more soluble in non-polar
organic solvents. Erroneous predictions were due to an incorrect understanding
of the polarity of the compounds.
In the fifth part of the experiment, the melting point of pure cinnamic
acid and pure urea, as well as 75%-25% mixtures of each (by mass) were tested.
The literature values for the melting point of cinnamic acid and urea are 133°C,
and were found to be within the range of 134-138°C and 131-137°C, respectively.
The mixture of 75% cinnamic acid was measured at 98-118°C, while that of 75%
urea was measured at 94-109°C. The results of the melting point portion of the
experiment are consistent with the literature and theory, which predict that the
mixtures have lower melting points due to the disruption in the regularly
ordered form of a pure compound.
Conclusion
In general, this experiment was successful in its goals, in that it
cemented an understanding of the way polarity and intermolecular forces affect
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