Analysis of hydrocarbons

Analysis of Hydrocarbons De Guzman, Ciara Nicole Gagan, Katrina Lee* Galvez, Camila Denise Gamboa, Jeriz Marie

2Bio7 College of Science, University of Santo Tomas, España Blvd., Manila.

Abstract: In this experiment, unknown samples were randomly given to us. To be able to identify the unknown reagents, we observed first the given organic samples named Toluene, Naphtalene, Hexane, and Hexene. After observing the said samples, we matched the unknown with the organic reagents given.

Introduction: Hydrocarbons are generally characterized by utilizing chemical reactions that are classified as addition or bond rupture reactions. In this experiment, we were able to differentiate various types of hydrocarbons, to distinguish hydrocarbon from each type, and characterize an unknown hydrocarbon through parallel chemical tests. The standards we used were Hexane, Hexene, Naphthalene, Toluene; the reagents we used were Nitrating agents which are highly corrosive, Bromine in DCM which is a suspect carcinogen, 2% KMnO4, 10% NaOH; and the laboratory tools we used were test tubes, test tube rack, droppers, beaker

Procedure/ Methodology: This procedure was for the Analysis of Hydrocarbons. In the nitration test, first we added 5 drops of Hexane, Hexene, Naphthalene and Toluene in each empty test tube. Then, we added 8 drops of sulfuric acid, shaked and added 20 drops of distilled water. In the bromine test, we added 3 drops Bromine reagent in each test tube. Then, we added 5 drops of Hexane, hexene, naphthalene and toluene in each of it. As well as 5 drops of unknown in U1, U2, U3 and U4 test tubes. In the basic oxidation test, we added 5 drops of hexane, hexene, naphthalene and toluene in an empty test tubes. Then, we

TEST/SOLUTIO N:

NITRATION TEST:

HEXANE HEXENE

No yellow oil No yellow oil

BROMINE TEST:

BASIC OXIDATION TEST: Dark green Dark brown

Red-orange soln. Immediate discoloration NAPHTHALENE Yellow ppt. Light yellow soln. Dark blue-green TOLUENE No yellow oil Carnation yellow Dark green soln. U1 No yellow oil Carnation yellow Violet soln. U2 Yellow ppt. Light yellow soln. Dark blue-green U3 No yellow oil Immediate brown discoloration U4 No yellow oil Red-orange soln. Dark blue added 3 drops of 2% KmnO4, 2 drops of 10% NaOH, shaked for 2 mins. And heated in a boiling water for 5 mins. Data & Results: The table of result is as follows:

As seen on the table above, in the nitration test only the test tube of naphthalene and unknown test tube #2 formed a yellow precipitate which means it showed a positive result. While, in the bromine test only the test tube of hexene and unknown test tube #3 had an immediate discoloration which means it showed a positive result.On the other hand, in the basic oxidation test only the hexene and unknown test tube #3 changed to brown color which means it showed a positive result. Based on the results from the table, it shows that the the unknown test tube # 1 is toluene, #2 is naphthalene,#3 is hexene and the unknown test tube #4 is hexane.

Conclusion Hydrocarbons are chemical compounds that are formed from only hydrogen atoms and carbon atoms. Alkanes contain single bonds. They are called saturated hydrocarbon. Their general molecular formula is CnH2n+2. Alkenes contain at least one double bond. They are called unsaturated hydrocarbon. Their general molecular formula is CnH2n. Alkynes contain one least one triple bond. Their general molecular formula is CnH2n-2. Aromatic Hydrocarbons (Arenes) are planar, ring structures with alternating single and

double bondsThe Aromatic Hydrocarbons which contains benzene ring are called benzoids (cyclic) and the compounds which do not contain benzene rings are called non benzoids (acyclic). It is important to understand which hydrocarbon compounds are saturated and which are unsaturated it determines and explains key chemical properties including the reactions of chemicals. Schematic diagram of hydrocarbons:

Hydrocarbo ns

Aliphatic

Saturated

Unsaturated

Aromatic

Alkylated

Nonalkylated

All standards that were used have parallel results with their corresponding unknown mentioned. Because of nitration test, bromine test and basic oxidation test, Unknown no. 13 is identified as toluene, unknown no. 14 is naphthalene, unknown no. 15 is hexene and unknown no. 16 is hexane. References: 1. Gagan,K.Laboratory Experiments in Organic Chemistry: Experiment 7, UST Publishing House,2015, pp. 41-42. 2. Allsbubjectsforyou. http://www.allsubjects4you.com/Hydrocarbons.htm. Retrieved on April 6, 2015.