Molecular Bonding & Properties: Infrared Spectroscopy & Boiling Point Study, Assignments of Chemistry

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Name: Date: Experiment #: 5

Title: Bonding and Properties

Purpose: Study the infrared spectra and physical properties of molecules to determine what kinds of intra-molecular bonds are present within the molecules and what kinds of inter- molecular bonds are present between the molecules. Procedure:

1. Add potassium chloride (ionic) to water in a test tube. Shake tube so potassium chloride dissolves.
2. Add pentate to test tube of water. Shake to see if it dissolves in the water.
3. Add normal propyl chloride to test tube of water
4. Add ethyl alcohol to test tube of water. Shake and observe
5. Add butyl alcohol to test tube of water. Shake and observe.
6. Add tert-butyl alcohol to test tube of water. Shake and observe.
7. Add acetic acid to test tube of water. Shake and observe.
8. Combine Pentane and normal propyl chloride in the same test tube.
9. Add iodine crystal to a test tube with pentane Boiling Point Study 10.Place tertial butyl alcohol into boiling apparatus. Measure temperature of vapors as it passes into condenser using a temperature probe. When temperature stabilizes, note the temperature as the boiling point 11.Do the same steps with the following substances to measure boiling points, ethyl alcohol , n- butyl alcohol , acetic acid , pentane, n-propyl chloride Infrared Spectroscopy 12.Add sample to IR. 13.Set instrument settings 14.Grind substance 15.Run program on IR. 16.Note IR spectrum 17. Data/Results/Calculations: White solid is at the bottom of the test tube with water and potassium chloride Pentate made a liquid layer on top. Did not dissolve. Normal Propyl chloride is a layer on top when added, and does not dissolve Ethyl alcohol dissolved in water.

Butyl alcohol does not dissolve in water and sits as layer on top of water. After shaking, the layer on top got smaller, but did not fully disappear. Tert- butyl alcohol created a layer on top of water at first, but then dissolved after being shaken. Pentane and normal propyl chloride dissolved with eachother. Iodine crystal turned the pentane purple as it dissolved. Boiling point study: Tertial butyl alcohol started to boil and the vapor temperature went up to 81. degree celsius. The following boiling points were recorded ethyl alcohol (76.4 C), n- butyl alcohol (115.3 C), acetic acid (116.2 C), pentane (34.8 C), n-propyl chlorid (46.3 C)

Conclusions: Potassium chloride is soluble in water which indicates that it is either a ionic, polar or hydrogen bonding compound. Pentane must be nonpolar because it does not dissolve. Because it has a long hydrocarbon chain.Normal Propyl chloride must be nonpolar because it does not dissolve. Some polarity, but still not soluble because it has a hydrocarbon chain. Ethyl alcohol must be either ionic, polar or hydrogen bonding because it dissolved in water. Butyl alcohol must be partially soluble in water. Ter-butyl alcohol must be either ionic, polar or hydrogen bonding because it dissolved in water. Acetic acid must be either ionic, polar or hydrogen bonding because it dissolved in water.Entane and normal propyl chloride dissolve because they are both polar.Pentane and iodine are both nonpolar and so they dissolved with eachother. Like dissolves in like. The intermolecular forces that are stronger, more energy is required to separate so that it turns into gas so the higher the forces, the higher the boiling point. Ionic>hydrogen boding>dipole dipole> Van der Waals. Higher molecular weights have higher boiling points. Molecules with greater degree of branching have lower boiling points because there is more surface area. That means that there needs to be more energy to separate molecules. KCl has the highest boiling point because it has the strongest intermolecular forces. Nonpolar substance pentane has the lowest boiling point because it has the weakes forces. Polar substance propyl chloride is the second lowest because it has the second lowest intermolecular forces. KCl spectrum is transparent and ther eare no absorption peaks because the bond does not absorb radiation within this region. Pentane has peaks that show that the intramolecular bonds of CH and CC. n propyl chloride has only CH, CC and CCl bonds due to peaks. Ethyl alcohol has intramolecular bonds CH, CC, OH and CO due to peaks shown. N Butyl alcohol has the CH, CC , OH, and CO bonds indicated.

T-butyl alcohol contains intramolecular CH, CC< OH, and CO bonds indicated. Acetic acid contains CH, CC, C=O, OH, and CO bonds indicated.

Notes: Slightly lower boiling points because the atmosphere pressure is slightly lower at Geneva College.