Matt Perry
Thomas Anderson
CHEM 1146 Lab
29 February 2018
“The Project” Lab Report
Introduction
This report discusses an experiment that a group of individuals carried out to potentially
save their environment. The experiment was inevitably sparked whenever the group of
individuals discovered an unknown solid ionic compound in their local landfill. Because of the
possible hazardous effects that the unknown compound could have on their environment, it
was urgent that they discover its identity. They were given a list of fifteen possible unknown
compounds, and ultimately proceeded to run tests on their unknown compound in order to
limit the number of possibilities down until they determined its identity. They ran four tests in
all to determine the identity of the unknown compound, which consisted of a cation and anion
analysis, a pH test, and a solubility test. This report presents the procedures for the
experiment, the experiment’s results, and an analysis of those results in regards to the effects
that the unknown had on its environment.
Experimental
In order to get a jump start on the discovery of the unknown compound’s identity that
they were working with, the lab group decided to begin their experiment with a cation analysis
procedure to determine the identity of the cation that was present in their compound. They
inevitably felt like this would potentially speed up the identification process, as the cation of a
compound essentially makes up one half of the compound by itself. They began to run a flame
test to determine the cation because they knew that many elements give off a specific color
whenever their electrons are excited to a higher energy state, which would be enacted by the
flame. They essentially knew that they would be able to determine the identity of the cation
that was present in the unknown by looking at the color of the flame produced. They began the
flame test by obtaining a nichrome loop and heated it in the flame of a Bunsen burner. They
then dipped the nichrome loop into the unknown solution and placed it into the flame. Once
doing this, they observed the color of the flame and recorded their observations accordingly.
After carrying out the cation analysis procedure, they decided to carry out an anion
analysis procedure in order to determine the identity of the anion present in their unknown.
They knew that once they discovered the anion that was present in the unknown compound,
they would have ultimately discovered the identity of the unknown compound as a whole, since
the anion makes up the second half of a compound. They tested for the presence of the
carbonate ion in the unknown compound as they placed 1 mL of the unknown solution in a test
tube, and added 6 M HCl one drop at a time into the unknown solution. The formation of
bubbles in the solution as the 6 M HCl was dropped into it would indicate the presence of the
carbonate ion being present in the unknown solution. The lab group looked for the formation
of bubbles in the solution and recorded their observations accordingly. The chemical reaction
equation for this reaction would be as follows: CO32- (aq) + 2 HCl (aq)  CO2 (g) + H2O + 2 Cl(aq).
After finishing up the cation and anion analysis procedures and ultimately discovering
the identity of the unknown compound, they proceeded to run a test to measure the pH of the
unknown compound in order to further prove its identity. They did this by measuring out 2 g of
the unknown and added it to 20 mL of distilled water to create a solution. They then used a pH
probe that was connected to a LabQuest device to determine what the pH of the solution was.
The pH value of the solution that was shown on the LabQuest was ultimately the pH value of
the unknown compound since it was made into a solution with distilled water. The lab group
proceeded to document the pH that was displayed on the LabQuest for the unknown
compound.
After the pH test, the lab group decided to conduct one final test to solidify the identity
of the unknown compound. For their final test, they decided to conduct a solubility
determination. They began to conduct this test by adding 2 g of the unknown compound into
one beaker, and adding 2 g of the stock compound that they believed was the same as the
unknown compound into a separate beaker. They proceeded to add distilled water to each of
the beakers until both mixtures were unsaturated. Once the solutions were unsaturated, they
began to add small amounts of each compound to its assigned beaker until the mixtures
became saturated again. After doing this, they determined the solubility of the unknown
compound as well as the stock compound and recorded their values accordingly. Finally, they
measured the temperature of the two mixtures and recorded that data as well.
Results and Discussion
Whenever the lab group carried out its first procedure to determine the unknown
compound, the cation analysis flame test, they ultimately were able to determine the cation
that was present in the unknown compound through it. Whenever they dipped the nichrome
loop into the unknown solution and placed it into the Bunsen burner flame, the flame’s color
inevitably turned from blue to an intense, bright yellow color. This intense, bright yellow color
that the flame gave off indicated that sodium was the cation that was present in the unknown
compound. Once they determined that sodium was the cation that was present in the
unknown compound, this allowed them to limit the number of possible unknown compounds
that they had down to just four compounds: NaCl, Na2SO4, Na2CO3, and NaC2H3O2.
Because they were able to do this, they decided to run the anion analysis procedure to
determine what the identity of the anion was in the unknown compound, which would
essentially allow them to determine the complete identity of it as a whole. Whenever they ran
the test and added the 6 M HCl one drop at a time into their unknown solution in the test tube,
bubbles began to form in the test tube. Because of the reaction that took place, the lab group
was able to confirm the presence of the carbonate ion in the unknown compound. Upon
learning this information, the lab group was then able to narrow down the number of possible
unknown compounds from four down to one, which was sodium carbonate.
After the carrying out the anion analysis test, the lab group conducted the pH test in
order to further confirm that the identity of the unknown compound was sodium carbonate.
Whenever they placed the pH probe into the unknown solution that they created, they sat back
and observed the value that was displayed on the LabQuest. They soon observed that the pH
value of the unknown solution was 10.52, which inevitably meant that the pH value of the
unknown compound was also 10.52. By finding this value, they were able to compare it to the
average pH value of the sodium carbonate compound to check for similarity. As the average pH
value for sodium carbonate is 11.26, the relatively similar pH value of 10.52 that they
determined for the unknown compound allowed for them to further accept sodium carbonate
as the identity of the unknown compound.
pH value of Unknown Compound
Average pH value of Sodium Carbonate
10.52
11.26
For their last test to ultimately finalize the discovery of the identity of the unknown
compound, they ran a solubility test to determine whether the unknown compound had the
same solubility characteristics as the stock sodium carbonate compound. They wanted to test
this because they knew that if the two compounds did have similar solubility characteristics,
they could ultimately confirm that the unknown compound was, in fact, sodium carbonate. As
they conducted the procedure by weighing out 2 g of both the unknown and the stock sodium
carbonate compounds and placed them in separate beakers, it took 25 mL of distilled water for
the unknown compound to become saturated and 19 mL of distilled water for the stock sodium
carbonate to become so. After this, it took the addition of 1.5 g of the unknown compound and
1 g of stock sodium carbonate compound for the solutions to become saturated. With the
unknown solution being saturated with 3.5 g of compound and 25 mL of distilled water and the
stock solution being saturated at 3.0 g of compound and 19 mL of distilled water, the
solubilities of the two compounds were similar. After observing this, the lab group concluded
that the unknown compound was sodium carbonate once and for all.
Unsaturated Unknown Solution:
2.0 g of compound w/ 25 mL of distilled
water
Unsaturated Stock Solution:
2.0 g of compound w/ 19 mL of distilled
water
Saturated Unknown Solution:
3.5 g of compound w/ 25 mL of distilled
water
Saturated Stock Solution:
3.0 g of compound w/ 19 mL of distilled
water
The experiments that the lab group conducted related to the goals of the lab in an wellfashioned manner. They were ultimately able to identify the unknown compound as being
sodium carbonate, as well as discover different chemical and physical properties of the
compound through them. They used very good experimental techniques throughout the
experiment as well, which allows for the experiments to be replicated by other individuals for
reliability purposes. Also, they were able to relate their findings to chemical literature during
the pH test, as they knew that sodium carbonate has an average pH value of 11.26. However,
they did manage to run into a bit of a problem with the pH probe as it was not reading at first,
but they eventually managed to fix it and use it to determine the pH value for the unknown
compound.
The fact that the lab group knew that cation and anions made up a compound was a
prime example of how the principles of chemistry were involved in the experiment. They knew
that by running the cation and anion analyses, they would ultimately be able to determine the
identity of the unknown compound because of this. A cation is essentially an “ion with a net
positive charge” and an anion is an “ion with a net negative charge” (Helmenstine). Since
compounds are “the result of two or more elements becoming chemically combined together,”
the sodium cation and the carbonate anion that the unknown compound consisted of allowed
the lab group to conclude its identity (IvyRoses.com).
As far environmental hazards are concerned, sodium carbonate really doesn’t portray
any. Sodium carbonate is essentially used as a builder in detergent powders, laundry additives,
and other cleaning products. Because of this, it could be thought that sodium carbonate may
cause harm on aquatic ecosystems whenever it seeps down the drain. This, however, is not the
case because waste water treatment plants will neutralize the carbonate and not allow it to be
discharged to the aquatic ecosystems. Also, sodium has a low toxicity so it will not inflict harm
on the aquatic ecosystems either.
Conclusion
Overall, the lab group did a great job of conducting the experiment. They managed to
meet all of the goals that were set out for them in the lab, and did this in an almost flawless
manner. They successfully concluded that sodium carbonate was the unknown compound by
running the four tests, and managed to save their environment of potential hazards through
doing so. Since the unknown compound ended up being sodium carbonate, the environment
was not in danger in the first place, but it was smart of the individuals to find this out for
themselves. As the saying goes, it is better to be safe than to be sorry.
References
HERA, Human and Environmental Risk Assessment on Ingredients of Household Cleaning
Products, 2005, vol. 2, pg. 2.
http://www.ivyroses.com/Chemistry/GCSE/What-is-a-compound.php, IvyRose Holistic, 7 March
2018.
https://www.thoughtco.com/cation-and-an-anion-differences-606111, Thought Co., 7 March
2018.