Project 1 Lab Report PDF

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Dencie Devora 2045L-027

Inorganic Contaminants Present in a Sample of Water INTRODUCTION: Determining the identity of an unknown compound or substance often appears behind the scenes of our daily lives—drug tests, forensic analysis, or even the recent lead poisoning issue that continues to plague the levels of Flint, Michigan. In situations such as these, the finding the type, as well as the amount of chemical involved can be very crucial in order to take action towards these issues. My group and I were assigned the chemicals A, B, and D. The tests that we conducted helped us identify the quantitative and qualitative characteristics of each chemical, which led us to find the identity if the chemicals that we were assigned. Theory: The main key scientific concepts that we needed to understand and utilize in this project are quantitative and qualitative analysis. Quantitative analysis deals with measurements and values —the pH test and the conductivity tests are quantitative measurements. Qualitative analysis involves looking at the physical attributes—the flame test and the solubility tests are qualitative measurements. The theory is that by conducting these tests we can use the information that we got to find the identity of the unknown. Hypothesis/Objectives: Our hypothesis as to the identities of the compounds we were assigned is as follows: A is ammonium chloride, B is calcium nitrate, and D is sodium chloride. We predicted these results after using our findings mainly from the conductivity, pH tests, and flame test. The objectives of week 1 was to determine the identities of the assigned chemical compounds through qualitative and quantitative analysis and create a hypothesis about the identities based on our findings. The objectives of week 2 was to conduct a solubility test using solutions of the chemical compounds (such as sodium hydroxide, hydrogen chloride, sodium carbonate, etc.) with the solutions of our assigned chemicals, as well as with our findings from week 1, to determine the identity of our assigned compounds. METHODS:

Dencie Devora 2045L-027

Safety: Students should: always wear their PPE, wash their hand thoroughly after conducting the experiment(s), use proper waste containers when disposing of their chemicals. Most of the chemicals may present hazards in the case of skin and eye contact, and ingestion. Part 1 Methods: Conductivity test: The purpose of the conductivity tests is to measure the resistivity of the compound to chemicals. To conduct this test, made a solution of our chemicals using 50 ml of water. Then we used a conductivity meter and placed it inside the solution we made with each of the chemical compound we were assigned, and we recorded the conductivity on the meter. pH test: The purpose of the pH test is to determine how acidic or how basic the compound is. To conduct this test, we placed a pH meter in the solutions of our chemicals and recorded the number that was listed on the meter. The pH of the water that we used was 7.4. Flame test: The purpose of the flame test is to find the color of the chemical when burned and use the findings to determine which cations are in our compounds based on the color emitted. To conduct this test, we used a nichrome wire and dipped in it HCl before using it to pick up our solid chemical and holding it up to the burner. We repeated this step for each of the chemicals, making sure to clean the nichrome wire time by dipping it in HCl and holding it up to the burner to ensure that no chemical is left on the wire. Solubility test: Precipitation reactions observed from solubility tests can be used to determine whether an element is present in a solution or not. The purpose of the solubility test is to see which chemicals precipitates in water, ethanol, or acetone—if the chemical precipitates, it could indicate what chemicals are in our compounds. We used a plastic precipitate tray and put each of the solutions of our assigned chemicals into the tray. Using a dropper, we dropped ethanol in each of the solutions to see if it precipitates. We used a watch glass for acetone. We put each of the solutions of our assigned chemicals on the watch glass and dropped acetone in each of the solutions to see if it precipitates.

Dencie Devora 2045L-027

Part 2 Methods: Solubility test: The purpose of the solubility test is to use the available chemical compound solutions and conduct a solubility test with our assigned chemical solutions to see which chemicals precipitate and therefore which chemicals are in our compounds. To conduct this experiment, we dissolved our each of our solid compounds in 40 ml of water and dropped each of the solutions into a plastic solubility tray. The chemical solutions we used to precipitate with our assigned chemicals are: sodium hydroxide (NaOH), hydrogen chloride (HCl), sodium carbonate (Na2CO3), magnesium sulfate (MgSO4), sodium oxalate (Na2C2O4), and barium chloride (BaCl2). RESULTS: Part 1 Results: Chemical

pH test

Conductivity test

Flame test (color)

A B D

6.7 6.4 7.3

(ms) 11.95 7.6 3.95

Colorless Colorless Yellow

Solubility: Ethano

Aceton

Predicted chemical compounds:

l Soluble Soluble

e Soluble

A: ammonium chloride (NH4Cl)

Soluble Soluble

Soluble

Soluble Soluble

Soluble

Water

B: calcium nitrate (Ca(NO3)2) D: sodium chloride (NaCl)

Dencie Devora 2045L-027

Part 2 Results: Solubility: Chemica

NaO

HC

Na2CO3 MgSO4 Na2C2O4 BaCl2

l

H

S

--

--

--

Key:

A

--

l --

B

S

--

S

--

--

S

D

S

--

S

--

--

S

--- = no precipitate, soluble S = precipitate, solid

Final Results: A: NH4Cl B: MgSO4 D: C2H3NaO2 (CH3COONa) DISCUSSION: Part 1 Discussion: We predicted that A is ammonium chloride (NH4Cl), B is calcium nitrate (Ca(NO3)2), and D is sodium chloride (NaCl) using results mostly from the conductivity test and the flame test. The solubility table was not referenced as all our chemicals produced no precipitates in water, ethanol, or acetone. We predicted that the cation for D is sodium because sodium emits a bright yellow color when it is burned and during the flame test, chemical D burned yellow. As for chemicals A and B, we compared results we found for the conductivity test and compared them with known conductivity values of chemical compounds and found that the conductivity values that we found for A and B were similar to the conductivity values of ammonium chloride (NH4Cl) and calcium nitrate (Ca(NO3)2) respectively.

Dencie Devora 2045L-027

Part 2 Discussion: According to our predictions in week one, chemical compound D contains the cation sodium and hydrogen, so we decided to use the NaOH and HCl solutions first to see if there would be precipitates. We found that chemical compound A is NH4Cl. Then we chose to use the Na2CO3 to see if any of our chemicals had calcium, barium, or hydrogen as cations because carbonate precipitates with calcium, barium, and hydrogen. Our results showed that all three of our chemical precipitates with Na2CO3. To further narrow results, we decided to use the MgSO4 and Na2C2O4 solutions to specify if our chemical compounds had barium or silver, because sulfate precipitates with barium and silver and acetate precipitates with silver only. Lastly, we chose to use BaCl2 because in the flame test during week 1, we found that B is colorless, and BaCl2 is used to find colorless chemical compounds. We concluded that B is MgSO4 and D is C2H3NaO2. Sources of Error: Some sources of error include inaccurate measuring tools, such as the conductivity meter and the pH meter which often fluctuated between two numbers, inaccurate preparation of solutions required for the tests, mistakes in calculations, and not using the right chemical solutions in the solubility tests. These possible sources of error could have messed up our results and prevented us from finding the identities of our chemical compounds. CONCLUSION: The objectives of this project are to determine the identities of the assigned chemical compounds through qualitative and quantitative analysis and to conduct a solubility test using solutions of the known chemical compounds with the solutions of our assigned unknown chemicals to determine the identity of our assigned compounds. Our hypothesis was that chemical compound A is ammonium chloride, B is calcium nitrate, and D is sodium chloride. Our hypothesis for chemical compound A was correct, but our predictions for chemical compounds B and D were incorrect. To reduce errors, particularly involving the solubility test, I would take care to be more accurate when creating the chemical compound solution used for the solubility test as the inaccurate preparation of solutions gave our group trouble during the solubility test.

Dencie Devora 2045L-027

RESEARCH CONNECTION: Hindawi - Journal of Chemistry In a study to the determine the presence of inorganic elements and compounds in the water supply of Tunceli, Turkey, samples of drinking water were taken from 28 sites. There has been no major industrial or agricultural development in this area and there is ample water supply due as the area receives a lot of rainfall and snowfall in the mountains. The purpose of the study is to determine if the quality of the drinking water. The study found that in all the 28 sites, the concentrations of the chemicals were below the maximum permissible amount set by local as well as international agencies. Five liters of water sample was taken from each site and analyzed in the laboratory using chromatography, where mixtures are separated. In conclusion, although there were traces of inorganic as well as some organic chemicals found in the water supply of Tunceli, Turkey, the traces of chemicals did not exceed the maximum permissible amounts. REFERENCES: Campbell, Carla, Rachael Greenberg, Deepa Mankikar, and Ronald D. Ross “A Case Study of Environmental Injustice: The Failure in Flint.” International Journal of Environmental Research and Public Health vol. 2016, 13 (951), p. 11, MDPI. https://www.mdpi.com/1660-4601/13/10/951/pdf. Accessed 2018 October 3. Demir, Veysel, and Sezai Ergin. “Occurrence and Assessment of Chemical Contaminants in Drinking Water in Tunceli, Turkey.” Journal of Chemistry, vol. 2013, no. 238374, 2013, p. 6. Hindawi, https://www.hindawi.com/journals/jchem/2013/238374/. Accessed 2018 October 4. Schaffer, Julie, and Corinne Herman. “Precipitation Reactions.” Chemistry LibreTexts Library, 2017, National Science Foundation, https://chem.libretexts.org/Textbook_Maps/Inorganic_Chemistry/Supplemental_Modul es_(Inorganic_Chemistry)/Descriptive_Chemistry/Main_Group_Reactions/Reactions_in_ Aqueous_Solutions/Precipitation_Reactions. Accessed 2018 October 4.

Dencie Devora 2045L-027...