Chemical Families Characteristics and Similarities PDF

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Chemical Families Characteristics and Similarities Experiment 3...

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Chemical Families: Characteristics and Similarities Chemistry Lab Report

February 12, 2021 Spring 2021

Chemical Families: Characteristics and Similarities Introduction In this experiment, three main classes of elements will be studied, which are classified as metals, nonmetals, and metalloids which are across the periodic table. These elements are arranged in a very unique way, which is in horizontal rows that are also known as periods, and vertical columns that are also known as groups or family. These elements are also accommodated based on their similarities and their chemical properties, as well as their atomic mass. Metals as well as non-metals can form ions positive or negative depending on if they are metal or non-metals. In a chemical reaction, metal atoms tend to lose electrons so they can become positive charge ions also known as a cation, In the same way as non-metals, they have the tendency of losing electrons so they become negative charge ions (anions). The purpose of this experiment was to see the similarities and predict some of the reactivities trends that these families will have based on their groups also, this experiment was to observe some aqueous solutions of ionic compounds that can be made in the groups of the periodic table. In this experiment, the groups that will be studied are, alkali metals that are in group 1A, alkaline earth metals that are found in group 2A, and halogens that are in group 7A. However, some tests were made in order to get to know the properties and reactivities of these elements, the experiment was split into three different parts. The first part of the experiment was to get to know the physical of common periodic families while in the second part of the experiment, a flame test was performed which was used to identify some elements, some common elements include metallic elements in ionic compounds. This test was performed along with the formation of precipitation, and halide reaction. The main idea of doing this was to get some knowledge in evaluating some chemical trends to later identify an unknown compound. In chemical

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compounds, many precautions must be taken because a lot of chemicals are very harmful to yourself as well as to your skin. In this experiment, there were some chemical and procedural hazards and some of them are chemicals that are harmful to aquatic life some others are very toxic to aquatic life, some chemicals may cause respiratory irritation, some can cause serious eye damage, can cause skin irritation, some can be may be harmful if swallowed, some others are chemicals are harmful if they come in contact with skin, some may intensify the fire, some may cause skin burn, some are toxic to aquatic organisms, and may cause long-term adverse effects in the aquatic environment some others danger of serious damage to health by prolonged exposure and another possible risk of impaired fertility. To avoid any of these hazards, everything had to be handled with care and the flammable compounds had to be away from the heat and also when the flame was open Also the tubing had to be checked for any holes or cracks to avoid liquidating. Procedures and materials Part I Physical Properties and Ions of Common Periodic Families Materials Vials containing about 3 mL of 0.5 M solutions of LiCl, NaCl, KCl, CaCl2, SrCl2, BaCl2, CuCl2, FeCl3 1. 1 mL of each known solution was placed in a 100x13mm test tube. Then the test tube was labeled and placed in a test tube rack. And then the Bunsen burner was adjusted to get a blue flame. 2. The wire loop was then cleaned by rinsing it with a small amount of DI water from a squeeze bottle. A test tube of 6M HCl was obtained. 3. The wire loop was dipped in 6M HCl and placed in the blue flame until it turned red. 4. The wire loop was dipped in the test tube containing the 0.5M LiCl. Then it was quickly placed in the flame. The change of color was then recorded. 5. Steps 3 to 5 were repeated for the solutions of NaCl, KCl, CaCl2, SrCl2, and BaCl2.

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Part II Analysis of Known Solutions: Chemical Properties A. Flame test Materials 0.5 M solutions of LiCl, NaCl, KCl, CaCl2, SrCl2, BaCl2, wire loop, 6 M HCl, DI Water, 100 mL beaker, 100x13mm test tubes a. Six test tubes were leveled with the compound formula LiCl, NaCl, KCl, CaCl2, SrCl2, and BaCl2. Then they were placed into the rack. b. 5 drops of 0.5M (NH4)2CO3. Was added to each of the test tubes. c. To the test tube that was labeled LiCl, 5 drops of 0.5M LiCl were added and then mixed. B. Solution Reactions Materials 0.5 M solutions of LiCl, NaCl, KCl, CaCl2, SrCl2, BaCl2, and 0.5 M solutions of test reagents (NH4)2CO3 and (NH4)2HPO4, 100x13mm test tubes, test tube rack a.

six test tubes with the compound formula LiCl, NaCl, KCl, CaCl2, SrCl2, and BaCl2 were labeled and placed in a test tube rack.

b. 5 drops of 0.5M (NH4)2CO3. Was added to each of the test tubes. c.

To the test tube that was labeled LiCl, 5 drops of 0.5M LiCl were added, and then it was mixed

d. Step 3 was repeated using a different ionic compound solution. e. Steps 1 to 4 were repeated using 0.5M (NH4)2HPO4 test reagent C. Halide test Materials 0.5 M NaBr, 0.5 M NaCl, 0.1 M NaI, hexane in a dropper bottle, 6M HNO3 in a dropper bottle, chlorine water (bleach solution), 100x13mm test tubes, test tube rack, parafilm squares to cover the test tube a. 10 drops of 0.5 M NaBr solution was added in a test tube. The test tube was labeled and placed in a test tube rack. b. 10 drops of hexane were added, 1 drop of 6M HNO3, and 5 drops of chlorine water. Cover with a parafilm and shake well. The color of the hexane upper layer was then recorded c. The steps 1 to 2 were repeated for 0.5 M NaCl and then, 0.1 M NaI

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Part III Analysis of Unknown Solution Materials Unknown solution, 0.5 M (NH4)2CO3, wire loop, 6 M HCl, DI water, hexane in dropper bottle, 6M HNO3 in dropper bottle, chlorine water (bleach solution) 100x13mm test tubes, test tube rack a. The unknown number was obtained from the instructor. b. 40 drops of the unknown solution were added to a test tube and placed in a test tube rack. c.

Using the procedure in Part II, the precipitation test was conducted with (NH4)2CO3 and halide tests first, followed by the flame test.

d. The observations were recorded. By using the knowledge obtained from Part I and II to the cation and anion of the unknown were determined. e. The chemical formula and name of your unknown solution was then identified. Part 1 Physical Properties and Ions of Common Periodic Families

Solution

Physical Properties

Cation Name/Formula

Anion Name/Formula

LiCl (D.1)

Clear Liquid Solution

Lithium Cation

Chlorine Cl-

NaCl (D.2)

Clear Liquid Solution

KCl (D.3)

+

Li

Sodium Cation Na

Chlorine Cl-

Clear Liquid Solution

Potassium Cation + K

Chlorine Cl

SrCl2 (D.4)

Clear Liquid Solution

Strontium Cation 2+ Sr

Chlorine Cl

CaCl2 (D.5)

Clear Liquid Solution

Calcium Cation 2+ Ca

Chlorine Cl

BaCl2 (D.6)

Clear Liquid Solution

Barium Cation Ba2+

Chlorine Cl-

CuCl2

Blue-green Liquid

Copper II Cation

Chlorine

+

4

(D.7)

Solution

Cu2+

Cl-

FeCl3 (D.8)

Yellow liquid Solution

Iron III Cation Fe3+

Chlorine Cl-

Part II.A

Analysis of Known Solutions: Chemical Properties/ Flame Test

Lithium Chloride (D.9)

Sodium Chloride (D.10)

Potassium Chloride (D.11)

Strontium Chloride (D.12)

Calcium Chloride (D.13)

Solution

Observation (Flame color with the solution)

LiCl

(D.9)

The flame of the color with the solution was hot pick (red)

NaCl

(D.10)

The flame of the color with the solution was yellowish /orange

KCl

(D.11)

The flame of the color with the solution was lavender (blue)

SrCl2

(D.12)

The flame of the color with the solution red-orange

CaCl2

(D.13)

The flame of the color with the solution was orange

BaCl2

(D.14)

The flame of the color with the solution was green-yellow

Barium Chloride (D.14)

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Part II. B Solution Reactions Solution Reaction Observations Ammonium Carbonate (NH4)2CO3

Solutions

Ammonium Hydrogen Phosphate (NH4)2HPO4

LiCl

(D.15) Clear solution no precipitate

(D.21) Clear solution no precipitate

NaCl

(D.16) Slightly pinkish no precipitate

(D.22) Clear solution no precipitate

KCl

(D.17) Clear solution no precipitate

(D.23) Clear solution no precipitate

SrCl2

(D.18) Cloudy solution with white precipitation

(D.24) Cloudy solution with white precipitation

CaCl2

(D.19) Cloudy solution with white precipitation

(D.25) Cloudy solution with white precipitation

BaCl2

(D.20) Cloudy solution with white precipitation

(D.26) Cloudy solution with white precipitation

Part II C. Halide Test Hexane Upper Layer Results NaBr

NaCl

NaI

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Solution

Hexane Layer Observation (Upper Layer Color)

Bromide, Br-

(D.27)

Observation on halide test orange upper layer color

-

(D.28)

Observation on halide test clear liquid upper layer color

Chloride, Cl Iodide, I-

(D.29)

Observation on halide test purple upper layer color

Part III Test Results #9 Flame Test

Solution Reaction Test

Halide Test

Calcium Chloride

Belongs to group 2A element

Chloride, Cl-

Orange color

White precipitation

Clear Solution

Solution Reaction Test : Ammonium carbonate (NH4)2CO3 Cloudy solution with white precipitation Ammonium hydrogen phosphate (NH4)2HPO4 Cloudy solution with white precipitation Therefore, the name of my compound was Calcium Chloride, CaCl2 which has a cation of Ca2+ and an anion of Cl-

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Discussion Some of the similarities that were observed in part I from the experiment were the solutions of compounds made of elements in group 1A, all appeared to be clear solutions. Among the solutions of compounds made of elements in group 2A, all appeared to be clear solutions as well. However in the solution made of compounds from the Transition metals, they appeared different in color with CuCl2 appearing with a blue color, and FeCl3 displaying a yellow color. Now, for the ionic charges of the elements, it was depending on the group that they were in that they were containing the same amount of electron charge. In metallic atoms, in group 1A all elements tend to lose one electron and become positive charge (cation) as in group 2A they lose two electrons and they become 2+charge (cation). While in non-metal atoms, elements in group 7A tend to gain one electron and so they become negatively charged (anion). Now for the transitional metals that were used was depending on the charge that the compound had. Now, when the non-metals and metals react, they form ionic compounds because they have opposite charges. Part II Analysis of Known Solutions: Chemical Properties The flame test is mostly used to identify the possible identity of metals that could be found in ionic compounds. The way that is performed is by dipping the wire loop in the container containing the compound and then placing it in the flame, the flame will then change color for a few seconds, and then it will go back to its original color. The same procedure was performed for Lithium Chloride, Sodium Chloride, Potassium Chloride, Strontium Chloride, Calcium Chloride, and Barium Chloride. All the compounds demonstrated different colors, each had a specific and unique color and this was observed by placing a wire loop in the flame while the original flame changed into the color that the compound demonstrated. Sodium-ion makes the test misleading

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because it is common contamination. The way it was removed is by dipping the wire loop in HCl and placing it into the flame until it gets red. Once this was done, the wire loop was dipped into the tube containing the compound and the results of the characteristics were as follows for alkali metals were LiCl which gave a color of hot pink, NaCl a color of yellowish/orange, and the last one lavender/blue. Now, for the alkaline earth metals, the characteristics were as SrCl2 as red-orange, followed by CaCl2 orange, and lastly BaCl2 which was green-yellow. So by performing the flame test, it cannot be concluded that it can be identified between group 1A and 2A elements because they all gave different colors. For instance, in the compounds made of 1A elements, the flame of LiCl was pink and KCl was blue so there was no similarity in the flame colors of elements in the same group. Solution Reactions In this part of the experiment, two test reagents were used; Ammonium Carbonate and Ammonium Hydrogen Phosphate. When these reagents reacted with compounds from group 1A and 2A the results indicated that the elements that belong to 1A had no precipitation and these compounds included LiCl, NaCl as well as KCl, and it is important to consider that all the elements that belong to the group 1A had (1+) cation. Now, the elements that belong to 2A had positive precipitation test precipitation and these compounds included CaCl2, SrCl2, as well as BaCl2, and the elements that belong to group 2A have a (2+) cation. Overall, the family that showed white precipitation was group 2A. And the importance of this test is because it lets you differentiate between group 1A and group 2A and find out how many ions does the element contain. Halide Test

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In this part of the experiment, the reagent that was used was hexane, this was used to identify the type of element from group 7A. The positive characteristics that were expected of the color of the hexane layer were bromide, chloride, and iodine. If it was yellow or pale it contained it had Chloride ion, if it was orange it contained bromide, and if it was white purple it indicated iodine. Part III Analysis of Unknown Solution For this part of the experiment, the known number that was assigned was unknown solution number nine. The flame color of this particular number was orange. In the unknown solution, the present element that was present was Calcium with 2+ ion (cation) and it also contained Chlorine Cl- with a negative ion (anion) the compound formula was CaCl2. When the solution reaction test was performed, the results of the unknown reaction indicated white precipitation meaning that the element belongs to family 2A with 2+ cation. This test was useful in determining the cation of the unknown solution. Once the halide test was performed, the clear solution indicated that the unknown ion was Cl- (anion). Overall, after performing part I and part II of the experiment with the unknown solution, the results indicate that the unknown chemical solution is Calcium Chloride CaCl2, Ca2+ (cation), and Cl-.

III. Conclusions Based on the outcome of the experiment, it can be concluded that the families of elements share similar properties. The test that can be used to identify an ion of an element is the flame test. Since each of the elements shows a specific color when exposed to the flame test it would show what element is based on it. Now, the test that was used to identify the ions of the element the flame test is because the flame test is used to identify metallic elements in ionic compounds

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now the test that helped to differentiate if the elements belong to the same family was a solution reaction. After all, in group 1A no precipitation was observed while in 2A white precipitation was observed. Once the flame test and the solution reaction was performed, and the identity of the unknown metallic element was found, a halide test was later performed to find out the identity of the other unknown ion and element in the group 7A, this was accomplished by reacting with hexane. With this test, it was accomplished to obtain the identity of the unknown halogen element. The results indicated that the unknown solution of the unknown element is Calcium Chloride (CaCl2). Some of the similarities that were observed by performing this experiment were first the solutions. They all had something in communion except for the Copper II chloride and for Iron III chloride that the liquid had different colors also, the number of ions, group 1A tend to give away 1 electron and they become cation and group 2A tend to give away 2 electrons and they become cation as well. Another similarity that was observed was during part II in solution reactions. The elements that belong to group 1A had no precipitation and the elements that belonged to group 2A did have precipitation. For instance, a practical application of unknown ionic compound determination is that it can be used maybe when the water from the faucet turns into a different color and smells weird. You would apply the unknown compound determination to find out what is contaminating the water.

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Post Lab Questions 1. What physical similarities did you observe from the solutions of compounds made of elements from Group 1A, 2A, and Transition Metals in Part I? Among the solutions of compounds made of elements in group 1A, all appeared to be clear solutions. Among the solutions of compounds made of elements in group 2A, all appeared to be clear solutions as well. However in the solution made of compounds from the Transition metals, they appeared different in color with CuCl2 appearing with a blue color, and FeCl3 displaying a yellow color.

2. Why do metals form positively-charged ions (cations), while non-metal elements form negatively-charged ions (anions)? Briefly explain using sample elements studied in the experiment. Metals form cations and nonmetals form anions because ionic bonds form only between metals and nonmetals. Metals “want” to give up electrons, and nonmetals “want” to gain electrons. For example in Calcium chloride, the molecule for calcium chloride has one calcium ion (+2) and two chloride ions (-1), which means that the overall charge for the molecule is 0, or neutral. 3. Can you conclusively identify the Group 1A and 2A elements using the flame test? Why or Why not? By using the flame test, I would say that I wouldn’t be able to identify between-group 1A and 2A elements because they all gave different colors. For example, in the compounds made of 1A elements, the flame of LiCl was pink and KCl was blue so there was no similarity in the flame colors of elements in the same group.

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4. What periodic trend can you observe when solutions made of elements from Group 1A and 2A reacted with ammonium carbonate and ammonium hydrogen phosphate? Explain briefly using your observations. To effectively differentiate Group 1A from group 2A in both known and unknown solutions, the flame test would be better for differentiating the groups in known solutions. However, the solution reaction test would be better to effectively differentiate the two groups in unknown solutions. 5. Between the flame test and solution reaction test, which one can be effectively used to differentiate Group 1A from 2A in both known and ...