Instructor: Dr. Emrani
Class: Organic Chemistry II Laboratory
Experiment/Lab: Infrared Spectroscopy
Date: 7-9-14 Introduction: IR spectroscopy deals with the infrared region of the electromagnetic spectrum, which is the light with a longer wavelength and lower frequency than visible light. A basic IR spectrum is essentially a graph of infrared light absorbance on the vertical axis vs. the frequency or wavelength on the horizontal axis. The electromagnetic spectrum usually divide the IR spectrum into three regions; the near, mid, and far. The near excites overtone or harmonic vibration (~14000-4000 cm^-1). The mid studies the fundamental vibration and the rotational vibration structure (~4000-400 cm^-1). The far studies the lying adjacent to the microwave region (400-10 cm^-1). The purpose of this lab is to learn various functional groups, to learn the important role of infrared spectroscopy in the study of the structure of organic compounds, to recognize the characteristics of absorption bands, and to be able to identify a compound by looking at the IR spectrum.
Chemicals and Reagents Used:
Potassium Bromide Salicylic Acid
Table of Physical Constant:
Molecular Weight (g/mol)
Melting Point (C)
Boiling Point (C)
Table of Data:
Equipment and Apparatus Used:
No reaction occurred.
1. Turn on the IRprestige-2 (Figure 1.a and 1.b). Click on the IR solution icon on the desktop (Figure 1.c) Once it’s on then let it load up so you can click on the background run button which is abbreviated BKG (Figure 2). Once BKG is click a spectrum should appear (Figure 3).
2. When that is done, then place the polystyrene film in the IRprestige-21 as shown in (Figure 4) and (Figure 5). Once it’s placed into the IRprestige-21 then click on calculate and a graph should appear as shown in (Figure 6). After that leave everything in the IRprestige-21 as shown in (Figure 5) and click on calculate again and a spectrum should appear as shown in (Figure 7). Then take everything out of the IRprestige-21 and start to prepare your sample.
3. Weight out 0.028g of salicylic acid and 0.150g of potassium bromide as shown in (Figure 8). Mix the salicylic acid and potassium bromide in the dry press as shown in (Figure 9). Make sure you dry press it as good as you can. Once it’s pressed good enough then place it inside the bolt but also make sure a screw is screwed to one end of the bolt as shown in (Figure 10) and (Figure 11).
4. After the mixture is inside the bolt then screw the screws into the other end of the bolt as shown in (Figure 12). Then try to tighten it as tight as you can so your disk looks like a transparent disk inside your bolt as shown in (Figure 13). If it isn’t transparent then you won’t get a good spectrum.
5. Place the bolt in the IRprestige-21 on the holder as shown in (Figure 14). Once that is set up, then obtain a spectrum of the sample by pressing measurement first then click on “sample” on the screen as shown in (Figure 15).
6. A spectrum should appear and that’s the end of the experiment, so then clean up your mess and leave.
Figure 1.c Figure 2
Figure 4 Figure 4
Figure 6: calculate is on the right side of the screen at the bottom.
Figure 8 Figure 8
Figure 8 Figure 9 Figure 9 Figure 10
Figure 11Figure 12Figure 13Figure 14 Figure 15
This is showing of the unknown that was performed during this lab experiment. If you look at Figure 15 you can see between 3520 cm^-1 and 3070 cm^-1 there is a…