Written-Laboratory-Report Group 7 Org Chem PDF

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Republic of the Philippines

Cebu Normal University College of Arts and Sciences Osmeña Boulevard, Cebu City 6000 Tel. No. : 253-0347

Name: Group 7: Cassandra Gayle Hera, Dan Raymond Russel Lajera, Kristine-Anne Limosnero, Francis Elrick Mendoza, Maria Daine Sabas Course and Year: BS Psychology - 2A

Date: Sep 15, 2021

Laboratory Report: Composition of Most Organic Compounds I.

Introduction

Organic compounds are chemical compounds that contain one or more carbon atoms covalently bonded to hydrogen atoms. It may also be bonded to a few other elements including oxygen and nitrogen. Organic compounds fundamentally consist of carbon which is noted for its ability to catenate or form long chains. Because life is based on carbon, it is considered the “backbone of life”. Therefore, it is abundantly present in our environment. In fact, the food we eat and the human body itself is largely composed of organic molecules such as carbohydrates, lipids, nucleic acids and protein. Given the natural abundance and essentiality of organic compounds, it is necessary to have a clear understanding of its nature including its makeup. This experiment aims to bridge the student’s theoretical knowledge with a practical understanding. In this experiment, inorganic compounds are made to react with organic compounds to test for the presence of carbon, hydrogen, nitrogen, sulfur, phosphorus, and halogens in the most common organic compounds. It seeks to provide a comprehensive knowledge of the elemental composition of organic compounds through experimental validation. This experiment should enable the students to identify and recognize these certain elements that compose the organic compounds people regularly come into contact with.

II.

Method A. Carbon and Hydrogen

Republic of the Philippines

Cebu Normal University College of Arts and Sciences Osmeña Boulevard, Cebu City 6000 Tel. No. : 253-0347

Materials Used: ·

Dry egg albumin

·

Test tube

·

Bunsen burner

Procedure: 1. Heat a small amount of egg albumin in a test tube. 2. Observe what is formed.

B. Nitrogen

Materials Used:

Procedure:

·

Dry egg albumin

·

Soda lime

1. Mix a small amount of dry egg albumin with an equal amount of soda lime in a dry test tube.

·

Red litmus paper

2. Heat the mixture in a test tube.

·

Test tube

·

Bunsen burner

3. Test the vapors by placing a moistened red litmus paper over the mouth of the test tube. 4. Observe the color of the litmus paper.

C. Sulfur

C.1 (with dry egg albumin) Materials Used: ·

Dry egg albumin

Procedure: 1. Mix a small amount of dry egg albumin with 5 ml of Sodium

Republic of the Philippines

Cebu Normal University College of Arts and Sciences Osmeña Boulevard, Cebu City 6000 Tel. No. : 253-0347

·

Sodium Hydroxide

Hydroxide.

·

Solution of lead (II) acetate

2. Heat the mixture for a few minutes.

·

Test tube

3. Cool the test tube in running water.

·

Bunsen burner

4. Add a few drops of lead (II) acetate solution. 5. Observe what happens.

C.1 (with hair) Materials Used: ·

Hair

·

Sodium Hydroxide

·

Solution of lead (II) acetate

·

Test tube

·

Bunsen burner

Procedure: 1. Mix a strand of hair with 5 ml of Sodium Hydroxide. 2. Heat the mixture for a few minutes. 3. Cool the test tube in running water. 4. Add a few drops of lead (II) acetate solution. 5. Observe what happens.

D. Phosphorus Materials Used: ·

Casein

·

Concentrated Nitric acid

·

Sulfuric acid

·

Ammonium molybdate

Procedure: 1. To a small amount of casein in a test tube, add 1 ml each of conc. Nitric acid and sulfuric acid. 2. Boil the mixture until the solution is clear.

Republic of the Philippines

Cebu Normal University College of Arts and Sciences Osmeña Boulevard, Cebu City 6000 Tel. No. : 253-0347

·

Test tube

·

Bunsen burner

3. Cool thoroughly and dilute the solution with an equal volume of water. 4. Add a small amount of ammonium molybdate solution and warm the tube in the water bath if no precipitate is found. 5. Observe what happens.

E. Halogens

Materials Used: ·

Nichrome wire

·

Watch glass

·

Vial

·

Bunsen burner

·

Concentrated Hydrochloric Acid

·

Chloroform

Procedure: 1. Clean a piece of nichrome wire by repeatedly dipping the end in a few drops of concentrated hydrochloric acid placed in a vial and heating it in the flame until the end of the wire imparts no color to the flame. It may be necessary to repeat the operation several times. 2. Place a few drops of chloroform by dipping the end of the wire on the watch glass and reheating it to the edge (oxidizing part) of the flame. 3. Observe the color imparted to the flame.

Republic of the Philippines

Cebu Normal University College of Arts and Sciences Osmeña Boulevard, Cebu City 6000 Tel. No. : 253-0347

III.

Results and Analysis

A. Carbon and Hydrogen When heated, the dry egg albumin turned black and moisture was formed at the walls and mouth of the tube. The charring of the albumin indicates the presence of carbon. When an organic compound was exposed to elevated temperature, it underwent thermal decomposition. Hydrogen and oxygen was removed during charring and what was mostly left was the carbon skeletal chains. Therefore, char, a carbonaceous material, was a product of an initial phase of combustion or carbonization. The stripped off hydrogen and oxygen were released into the atmosphere as water vapors which explained the moisture formation in the tube. B. Nitrogen When the soda lime and dry egg albumin was heated, a distinguishable pungent smell was noticed. Upon testing the vapors with the damp red litmus paper, the paper turned into blue which means that the gas was alkaline. The colorless gas with a distinct bad smell that was released was ammonia or NH3, thereby proving the presence of nitrogen in the organic compound albumin. The soda lime liberated the ammonia gas from the albumin.

C. Sulfur C.1 (with dry egg albumin) When the mixture of albumin and Sodium hydroxide (NaOH) was heated, the egg albumin dissolved and a clear yellow solution was formed. Sodium hydroxide acted as the converter or the ‘liberator’ for the sulfur in the dry egg albumin. Adding Lead (II) acetate Pb(CH3COO)2 turned the solution to brown and resulted in the formation of dark brown precipitates that settled at the bottom of the tube, which was Lead (II) sulfide. Thus, indicated the presence of Sulfur.

Republic of the Philippines

Cebu Normal University College of Arts and Sciences Osmeña Boulevard, Cebu City 6000 Tel. No. : 253-0347

C.2 (with hair) When the strand of hair in sodium hydroxide (NaOH) was heated, the hair dissolved and a clear brown solution was formed. When the lead (II) acetate was added, a dark brown precipitate was formed. This was the formation of Lead (II) sulfide. Thus, indicated that there was indeed the presence of Sulfur in hair, particularly in the protein keratin which is an organic compound.

D. Phosphorus When the mixture of casein, nitric acid and sulfuric acid was heated, the casein was dissolved. Thereby, forming a clear yellow solution. Yellow smoke was also observed. Steam and bubbles appeared when the solution was diluted with water and it turned into a brighter yellow. When ammonium molybdate was added, yellowish crystalline precipitate was formed. This layer of bright yellow was ammonium phosphomolybdate or (NH4)3PMo12O40 . The acid ammonium molybdate reacted with the phosphate ions therefore forming the ammonium phosphomolybdate. Thus, indicating the presence of phosphorus in the organic compound casein. E. Halogens When the nichrome wire dipped in chloroform was heated to the edge of the flame, it produced a bright green flame. This proved the presence of chlorine in the chloroform (CHCl₃) solution. Halogens like chlorine gave a bright green color to the flame.

IV.

Discussion A Charring test was used to determine whether a substance was organic or inorganic. Charring indicates that it was an organic substance. Char is a product of an initial phase of combustion and it is a carbonaceous material in nature. In the test for carbon and hydrogen, the charring of the egg albumin confirmed the presence of carbon. The moisture formed at the walls and mouth

Republic of the Philippines

Cebu Normal University College of Arts and Sciences Osmeña Boulevard, Cebu City 6000 Tel. No. : 253-0347

of the tube as well as water vapor confirmed the presence of hydrogen and oxygen. The test for some elements in organic compounds was quite a challenge since these compounds are in covalent bonds. Experimenting to detect the presence of elements would require a converter or a “liberator” first that would turn the organic element into an inorganic one. Reagents would then be added and these would confirm the presence of the element. In the test for nitrogen, the pungent smell was from the ammonia released upon heating the mixture of soda lime and albumin. Soda lime was the liberator of the ammonia gas in the egg albumin. This confirmed the presence of nitrogen. Soda lime was used to liberate nitrogen from nitrogen-containing compounds. Similarly, in the test for sulfur, sodium hydroxide liberated sulfur from the egg albumin. Sodium hydroxide was used to liberate sulfur from sulfur-containing compounds. In addition, the reagent which was lead (II) acetate was added to the solution, it reacted and resulted in dark brown precipitates or the lead (II) sulfide. Thus, confirmed that sulfur was indeed present in the organic compound. The hair which is made up of the protein keratin, an organic compound, also had sulfur content. The hair was dissolved in sodium hydroxide and when added with lead II acetate, lead (II) sulfide was formed, thereby confirming that there was sulfur content in protein keratin in the hair. In the test for Phosphorus, a mixture of nitric acid and sulfuric acid in equal amounts converted the organic phosphorus within the casein, into inorganic phosphorus. This formed a yellow solution and a yellow smoke. The mixture of nitric acid and sulfuric acid was the liberator of phosphorus from phosphorus-containing compounds. The mixture of casein, nitric acid, and sulfuric acid was diluted with water, turning it to bright yellow and bubbles had appeared. The reagent, ammonium molybdate added to the diluted mixture, reacted and formed a yellow precipitate which was ammonium phosphomolybdate. Thus, confirmed the presence of phosphorus. Testing the presence of Halogens such as Chlorine in organic compounds was difficult since ionic bonds are weaker than covalent bonds. A bright green flame was produced upon heating the nichrome wire dipped in chloroform,

Republic of the Philippines

Cebu Normal University College of Arts and Sciences Osmeña Boulevard, Cebu City 6000 Tel. No. : 253-0347

therefore indicating the presence of chlorine. The green flame was due to the decomposition of the halide.

V.

Conclusion Organic compounds are generally carbon-containing compounds that are in covalent bonds to hydrogen atoms. Carbon has the ability to form longer chains thus, it could bond to few other elements. Most organic compounds are composed not only of carbon, but also of a few other elements such as hydrogen, oxygen, nitrogen, sulfur, phosphorus and the halogens. The natural abundance of organic compounds in our everyday environment leads to the significance of understanding its composition and nature as well. Experiments were made to test the presence of such elements in organic compounds. Inorganic compounds were made to react with organic compounds to test the presence of the elements carbon, hydrogen, nitrogen, sulfur, phosphorus, and halogens in some of the most common organic compounds. Covalent bonds are hard to break thus, directly extracting the elements from the compounds are not doable without the help of the liberators and reagents. To break the covalent bonds, liberators were needed to be added beforehand, as used in the respective tests for nitrogen, sulfur, and phosphorus. And then, reagents were needed to be added in order to identify the presence of the element being tested. The soda lime, Sodium hydroxide, Lead (II) acetate, mixture of nitric acid and sulfuric acid, ammonium molybdate, and copper converted the organic chemicals to inorganic ones, and were indicators for the said compositions of the several organic compounds. Soda lime was used to liberate nitrogen from nitrogen-containing compounds. Sodium hydroxide was used to liberate sulfur from sulfur-containing compounds. Lead (II) acetate added to the solution reacted and formed lead (II) sulfide. Therefore, it could be used to determine the presence of sulfur in compounds. The mixture of nitric acid and sulfuric acid (1:1) was used to liberate phosphorus from phosphorus-containing compounds. Ammonium molybdate when added would react to a sulfur-containing compound, as it formed

Republic of the Philippines

Cebu Normal University College of Arts and Sciences Osmeña Boulevard, Cebu City 6000 Tel. No. : 253-0347

ammonium phosphomolybdate. When it reacted with a sulfur-containing compound, ammonium phosphomolybdate was formed. Thus, ammonium molybdate could be used to determine if there was phosphorus in a compound. We regularly come across and come in contact with organic compounds in an everyday life scenario. Understanding the basics and the makeup of these organic compounds would help us understand the compounds and also educate us how to make good use of them. It is also rather important to learn about these basic compounds before we can fully understand the makeup and the usage of the more complex ones.

VI.

Questions 1. Why is it more difficult to test for the presence of chlorine in organic compounds than in inorganic compounds like HCl? It is difficult to test for the presence of chlorine in organic compounds since chlorine is an inorganic compound. As the saying goes, like dissolves like therefore, organic compounds dissolve or mix with organic compounds. Chlorine can only be easily detected in inorganic compounds like HCl and water. 2. When a piece of hard-boiled egg is left in contact with a silver spoon, a black spot is formed on the spoon. Explain. The egg white or albumen contains more than half of the egg’s total sulfur. During the boiling of the egg, the bonds in its molecular structure that contain the sulfur or hydrogen sulfide group are broken through hydrolysis. This process releases the sulfur and hydrogen sulfide groups. When in contact with the silver spoon, these compounds lead to the formation of silver sulfide through oxidation. Silver sulfide is an inorganic compound with the formula Ag₂S and has a black color.

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Cebu Normal University College of Arts and Sciences Osmeña Boulevard, Cebu City 6000 Tel. No. : 253-0347

VII.

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Republic of the Philippines

Cebu Normal University College of Arts and Sciences Osmeña Boulevard, Cebu City 6000 Tel. No. : 253-0347

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