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Finding an Unknown White
Compound Using Physical and
Chemical Property Tests
Chemistry 1065 Spring 2023
Alex Wu
Lucas Harrison
Anna Dittrich
Katie Reimer
Abstract
The purpose of this experiment was to identify an unknown white compound(UWC)
through a battery of physical and chemical tests. These tests included a flame test, a PH test, a
conductivity test, and an ion test. The PH test confirmed that the UWC was basic. The flame test
confirmed the presence of Sodium by eliciting a bright orange-yellow flame. Using ion tests, any
compounds that contained Ca
2+
, Cl
-
, SO
4
2-
, and CO
3
2-
were ruled out. This meant that through
deduction, the UWC was sodium acetate, NaC
2
H
3
O
2
. After discovering the UWC was NaC
2
H
3
O
2
through physical and chemical tests,
NaC
2
H
3
O
2
was successfully synthesized and confirmed by
running the newly synthesized compound through an ion test.
1.
Introduction
This type of experiment relates to real-world applications as unknown compounds can
often be found in various places, such as commercial products, hospital wards, and research
facilities. The presence of these compounds is a major cause of concern as they can pose a major
and immediate risk to the safety and efficiency of anyone or anything in contact with these
contacts. In a report by Paul Waller, a chemist at SOCOTEC, a chemical management group,
Waller described the process of discovering the identity of a deposit on engines that reduced
vehicle power availability. Waller conducted Fourier Transformed Infrared Spectroscopy on the
deposit to test for adhesives, polymers, fabrics or inorganic salts. (Waller) Next, Waller used Gas
Chromatography-Mass Spectroscopy to find any organic compounds in the compound. (Waller)
Finally, Scanning Electron Microscopy was used to find the elemental composition of the
element. (Waller) Although Waller's techniques were much more advanced and unavailable for
use in this experiment, the purpose and process were the same.
Unknown compound identification research is particularly useful and interesting for
researchers interested in human development. Human milk contains many bioactive nutrients,
fats, and proteins that are crucial for babies’ development(“NIST Expands Database That Helps
Identify Unknown Compounds in Milk | NIST”); researchers use chemistry to find these specific
“miracle” compounds in human milk so that they can be added to baby formulas. (“NIST
Expands Database That Helps Identify Unknown Compounds in Milk | NIST”) In a 2023 paper
published in the journal Nutrition, scientists used
ultra-performance liquid chromatography–Q
Exactive–HF hybrid quadrupole–Orbitrap–mass spectrometry to detect the presence of specific
human milk oligosaccharides(HMOs) in babies' feces. (Li et al.) Understanding the presence of
these HMOs in feces can allow for a better understanding of the development of the human
digestive system in early life. (Li et al.) Once again, the techniques used were far beyond the
ones used in this experiment, but the process and purpose remained the same.
This experiment aimed to discover the identity of a provided unknown white
compound(UWC) through a comprehensive battery of physical and chemical tests. Due to the
nature of this experiment, hypotheses cannot be provided as the chemical could be any of the 15
compounds provided. However, if the tests are properly performed, then the compound will be
identified and synthesized within the parameters of the experiment.
2.
Experimental
A variety of tests were performed to identify the UWC. To shrink down the possible
number of compounds, the first test performed was a PH test, this test is not specific, so it will
shrink down the list substantially. Using a few PH strips, a beaker, distilled water, and the UWC,
prepare a solution using the UWC with the distilled water in the solution. Dip the PH strip into
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the solution and examine the color.
To continue narrowing down the number of possible compounds, a flame test was then
performed. Gather a Bunsen burner, matches, rubber tubing, neochrome wire, 6M HCL, distilled
water, the UWC, and 2 beakers. Make a slurry of the UWC by mixing 1.55g of UWC with a few
drops of distilled water. Set up the bunsen burner by attaching the rubber tubing to the gas and
lighting the bunsen burner with matches. Adjust the flame of the Bunsen burner until it turns
blue, ensuring accurate results. Clean the neochrome wire by dipping it into the 6M HCL
solution and rinsing it with distilled water. Run the cleaned and dry nichrome wire through the
flame. If the fire does not change color, the wire is clean. Let the wire cool, scoop out a small
amount of the UWC slurry with the wire and move the wire into the flame. Record any color
changes. Clean the wire between each trial.
Ion tests for Ca
2+
, Cl
-
, CO
3
2-
, SO
4
2-
were then performed. Prepare a dense solution of the
UWC and distilled water. Add 1 ml of the solution to 4 different test tubes. Test for Ca
2+
by
adding a few drops of NaOH to the UWC solution. Observe for any precipitate formations. Test
for CO
3
2-
by adding a few drops of HCl to the UWC solution. Observe for any fizzing or
effervescence. Test for Cl
-
by adding 1mL of 6M HNO
3
, and 1mL of 0.1M AgNO
3
to 1mL of
UWC solution. Observe for any precipitate formations. Test for SO
4
2-
by adding 1mL of 6M HCl,
1mL of 0.1M BaCl
2
to 1mL of UWC solution. Observe for any precipitate formations. For
increased certainty, a conductivity test was performed. After cleaning the probe, it was connected
to the computer and GoLink! Interfaces. Solutions of NaCl, the UWC, Na
2
SO
4
, and CaCO
3
were
created. Dip the probe into each solution and record the graphs, cleaning the probes after each
solution. Compare the graphs of each compound with the graph of the UWC.
The UWC was synthesized using 12.2 ml of 6M acetic acid with 1.025g of sodium
bicarbonate. This solution was then boiled down on a hotplate and weighed. To confirm the
presence of the UWC in the synthesized compound, repeat the above procedure for a CO
3
2-
ion,
PH, and flame test.
After testing, all solutions were neutralized and disposed of per MSDS
guidelines.
3.
Results
Data Table 1:PH test (UWC)
Trial
Observation
Trial 1
Neutral
Trial 2
Neutral
Trial 3
Neutral
Trial 4
Basic
Trial 5
Basic
Trial 6
Basic
As shown in Data Table 2, the PH test was neutral and basic.
Data Table 2: Color Observed From Flame Test (UWC)
Trial
Color Observed
Trial 1
Yellow
Trial 2
Yellow
Trial 3
Yellow
As shown in Data Table 2, the flame test was consistently yellow.
Data Table 3: Observations From Ion Tests (UWC)
Ion Tested
Observations
Ca
2+
No precipitate formation
Cl
-
No precipitate formation
SO
4
2-
No precipitate formation
CO
3
2-
No fizzing or effervescence
As shown in Data Table 3, no precipitate formation, fizzing or effervescence was observed.
Data Table 4: Measurements for the synthesis of Sodium Acetate(
NaC
2
H
3
O
2
)
Volume
of acetic
acid
Moles
of acetic
acid
Volume of
sodium
bicarbonate
Moles of
sodium
bicarbonate
Mass of
synthesized
compound
Theoretical
mass of the
synthesized
compound
Percent Yield
12mL
0.150
1.025g
0.171
0.92g
1g
92%
Equation 1: Balanced chemical equation for the synthesis of sodium acetate(
NaC
2
H
3
O
2
)
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NaHCO3 + C2H4O2 = CO2 + NaC2H3O2 + H2O
Acetic acid(NaHCO
3
) and sodium bicarbonate(C
2
H
4
O
2
), shown in data table 4, were reacted in
proportional volumes following Equation 1.
Data Table 5: Observations From Ion Tests (synthesized compound)
Ion Tested
Observations
CO
3
2-
No fizzing or effervescence
As seen in Data Table 5, no fizzing or effervescence was observed in the synthesized compound.
Data Table 6 Observations From Flame Tests (synthesized compound)
Trial
Color Observed
Trial 1
Yellow
Trial 2
Yellow
Trial 3
Yellow
As seen in Data Table 6, a yellow flame was consistently observed in the synthesized compound.
Data Table 7: PH test (Synthesized Compound)
Trial
Observations
Trial 1
Basic
Trial 2
Basic
Trial 3
Basic
As seen in Data Table 7, the synthesized compound was consistently basic.
6. Discussion
The first test performed was a PH test. The consistent basic measurement allowed the list
of possible compounds to be narrowed down to exclusively basic ones.
Due to the consistent observation of a yellow-colored flame during the flame test,
indicating the presence of a sodium cation in the UWC. This is due to sodium’s relatively low
electron energy levels. Sodium’s electrons absorb the energy from the flame, so when they drop
down from their excited state, they release a relatively low energy wavelength, causing the
yellow flame.
After testing for the sodium cation, specific ion tests were performed. Based on the
provided list, the remaining chemicals had ions that were Ca
2+
, Cl
-
, CO
3
2-
, SO
4
2-
. The
observations from this test were used to eliminate all of these ions. Ca
2+
was eliminated because
calcium carbonate was not formed when NaOH was added to the UWC. Cl
-
was eliminated
because silver chloride was not formed when HNO and AgNO
3
were added to the UWC. CO
3
2-
was eliminated because fizzing due to CO2 formation was not observed when HCl was added to
the UWC. SO
4
2-
was eliminated because BaSO4 formation was not observed when HCl and
BaCl
2
were added to the UWC.
An experimental error occurred in this step. After observing negative test values for each
of the possible ions, the entire list of possible ions was eliminated. After retesting the ions and
performing an extra conductivity test, it was found that the PH strips used were faulty. After
retesting the UWC solution with new PH strips, along with a discussion with the lab instructor,
the compound was found to be basic. This, combined with the previously performed ion, flame,
and conductivity tests, concluded that the UWC was sodium acetate.
As shown in Data Table 4, the percent yield of the UWC was 92%. The lower percent
yield could be attributed to rounding errors within the calculation or undesired side reactions that
could have occurred. The synthesized compound was retested by performing a CO
3
2-
ion test,
flame, and PH test. With the CO
3
2-
showing no CO2 precipitate formation, the flame test turning
yellow, showing the presence of a sodium cation, and the PH test reading basic, the UWC was
adequately verified to be sodium acetate.
7. Conclusion
The objective of this experiment was to identify, verify, and synthesize the UWC. This
was accomplished using a comprehensive battery of physical and chemical tests consisting of
flame, PH, conductivity, and ion tests. The PH test narrowed the list down to exclusively basic
compounds. The flame test was used to determine the presence of a sodium cation. The ion tests
were used to eliminate the possibilities of Ca
2+
(no precipitate formation), Cl
-
(no precipitate
formation), CO
3
2-
(no bubbling) and SO
4
2-
(no precipitate formation). A conductivity test was
conducted for further verification. After performing these tests, it follows trivially that the
compound would be sodium acetate.
The UWC was synthesized using 12.2ml of 6M acetic acid with 1.025g of sodium
bicarbonate, yielding 0.92g of sodium acetate. After removing all water, an elementary
calculation shows that the percent yield was 92%. The synthesized compound was confirmed by
repeating the flame(yellow), PH(basic), and CO
3
2-
(negative)
ion test.
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The work done in this experiment can be expanded on by using more advanced and
efficient techniques on the UWC, such as
Scanning Electron Microscopy, to find the elemental
makeup of the compound. This extension would be meaningful as it would lead to a more
efficient pathway to the UWC and strengthen the claim of identifying the UWC.
A use case for this experiment would be utilized by individuals who need to safely
identify, use, and dispose of sodium acetate.
8. Works Cited
Li, Rui, et al. “Comparative Analysis of Oligosaccharides in Breast Milk and Feces of
Breast-Fed Infants by Using LC-QE-HF-MS: A Communication.”
MDPI
, Nutrition, 9
February 2023, https://www.mdpi.com/2072-6643/15/4/888. Accessed 18 October 2023.
“NIST Expands Database That Helps Identify Unknown Compounds in Milk | NIST.”
National Institute of Standards and Technology
, 27 July 2020,
https://www.nist.gov/news-events/news/2020/07/nist-expands-database-helps-identify-
unknown-compounds-milk. Accessed 18 October 2023.
Waller, Paul. “The Secret Behind the Characterisation of Unknown Materials| SOCOTEC
UK.”
Socotec
, 24 March 2017, https://www.socotec.co.uk/media/blog/characterising-
unknowns-behind-the-scenes-of-chemical-investigation. Accessed 18 October 2023.
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