Chemistry Notebook 6

docx

School

Portage Learning *

*We aren’t endorsed by this school

Course

103

Subject

Chemistry

Date

Feb 20, 2024

Type

docx

Pages

Uploaded by kieriabrewer

Chemistry Notebook Name: Kieria Brewer Date: 07/24/2023 Experiment #: 6 Title: Bonding & Properties Purpose: To study the infrared spectra and bonds between and within molecules Procedure: Solubility Experiment Starting with 7 test tubes that are filled about a quarter of the way with water. A small amount of potassium chloride is added to the first test tube with water. The test tube is agitated to mix the water with the potassium chloride. Record whether potassium chloride was dissolved in water. This process is repeated for the substance pentane. Since this is a liquid there is an obvious layer between the water and the substance that does not go away. n-propyl chloride is added to a test with water like pentane. These steps are repeated for the remaining 4 substances, Ethyl alcohol, Acetic acid, n-Butyl, and t-Butyl alcohol. Record the solubility for each. Pentane is added in a test tube instead of water. n-Propyl chloride is added to the same test tube and mixed. Record if substances mix or are insoluble. Boiling Point Experiment A distillation apparatus is used to determine the boiling point of each of the seven substances except for potassium chloride. A small sample of each substance is added to the flask on the distillation apparatus. Once heat begins to boil the liquid, the vapor will rise to meet the temperature probe and the temperature will begin to climb. The temperature is recorded once the temperature is constant. This process is repeated for the remaining substances using clean equipment for each except for potassium chloride. Infrared Spectroscopy Using a provided infrared spectroscopy, add a small amount of one of the seven substances. Adjust the instrument settings begin the scan and record the results of each substance. Repeat until all 7 substances have been analyzed. Data/Results/Calculations: Solubility Experiment

Chemistry Notebook Potassium Chloride is soluble in water and is an ionic compound. Ethyl alcohol, t-butyl alcohol, and acetic acid were all soluble in the water. These 3 substances are hydrogen bonding compounds. N-butyl alcohol was partially soluble in the water. This substance does have hydrogen bonding characteristic, but the nonpolar 4 carbon chain makes it partially soluble. Pentane and n-propyl chloride were both insoluble in water, likely due to the longer carbon chains these molecules contain. These two compounds are soluble within each other. This is due to the rule of "like dissolves like’. Boiling Point Experiment In this experiment, the highest boiling point was potassium chloride, which was too high to obtain in the lab. Acetic acid and n-butyl alcohol had the second highest boiling points. The third highest boiling points were t-butyl alcohol and ethyl alcohol. n-Propyl chloride and pentane had the lowest boiling points. Infrared Spectroscopy The potassium chloride's scan was transparent throughout meaning that the K-Cl bonds do not absorb radiation. Pentane saw peaks between 3000-2800 cm-1, at 1460, and 1380. Pentane only has intramolecular C-H and C-C bonds. N-propyl chloride had several peaks at 3000-2800 and saw additional peaks at 1380, 730, and 650 indicating the presence of C-H, C-C, and C-Cl bonds. Ethyl alcohol peaked at 3400-3200, 3000-2800, 1500-1300, and1050 indicating the presence of C-H, O-H, C-C, and C-O bonds. N-butyl alcohol peaked at 3700-3600, 3400-3300, 3000-2800, 1500-1300, and 1050 indicating the presence of C-H, C-C, O-H, and C-O bonds. T-butyl alcohol peaked at 3500-3200, 3000-2800,1500-1300, and 1200 indicating the presence of C-H, C-C, O- H, and C-O bonds. Acetic acid peaked at 3400-2500, 1700, 1500-1400, and 1300-1200 indicating the presence of C-H, C-C, C=O, O-H, and C-O. Substance Molecular weight Dipole Movement Water soluble? Boiling point ( C) Types of bonds Potassium Chloride 74.5 10.2D yes 1420 K-Cl Ethyl alcohol 46 1.7D Yes 76.4 C-H O-H C-C C-O Acetic Acid 60 1.5D Yes 116.2 C-H C-C C=O O-H C-O n- Butyl alcohol 74 1.7D Partially 115.3 C-H C-C O-H C-O

Chemistry Notebook t-Butyl alcohol 74 1.7D yes 81.5 C-H C-C O-H n-Propyl Chloride 78.5 2.1D no 46.3 C-H C-C C=Cl n-pentane 72 0D no 34.8 C-H C-C Conclusions: In general, Ionic bonds and H-bonds are more likely to be soluble in water while compounds with fewer or no polar bonds will likely be insoluble. The high boiling point for potassium chloride is due to the strong intermolecular forces since the compound is ionic. Acetic acid and n-butyl alcohol are Hydrogen bonded which causes a higher boiling point. A molecule that is nonpolar has weaker intermolecular forces which is why n-Propyl chloride and pentane had the lowest boiling points. The results of the infrared spectroscopy can be compared with predictions from the solubility experiment and the boiling point experiment to determine what bonds are present, they are listed in the chart above. Notes:  Solubility Study o Inter-molecular bonding can be indicated by studying the solubility of substances in water which is a hydrogen bonding polar solvent. o Ionic, polar or hydrogen-bonding substances will be soluble in water. o Compounds which have few or no polar bonds or much hydrocarbon content will be insoluble in water.  Molecular bonding can often be determined from studying the physical properties of the molecule  The stronger the inter-molecular forces, the more energy required to separate them.  Higher molecular weight molecules will have higher boiling points.  Molecules with a greater degree of branching will have lower boiling points.  Ionic bonds have the strongest inter-molecular forces  Hydrogen bonding second strongest molecular force  A infrared spectrometer is an instrument that passes a beam of infrared light through a sample causing the bonds of the sample molecules to bend or stretch as IR energy of certain wavelengths are absorbed.  A graph (spectrum) of the transmitted light is generated which contains inverted peaks corresponding to the absorption of energy by the bonds.  Analysis of the position of peaks in this spectrum reveals what bonds are present and how these bonds are arranged

Your preview ends here

Eager to read complete document? Join bartleby learn and gain access to the full version