CHM260 lab 3 - lab report PDF

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CHM260 BASIC INSTRUMENTAL ANALYSIS LABORATORY SUMMARY WRITTEN REPORT Name : MUHAMAD ATIFF BIN MAZLAN ID No. :2018232038 Programm :AS120 e Instructor : DR YUSWANIE BT MD YUSOF EXPERIMENT 3 FOURIER TRANSFORM INFRARED SPECTROSCOPY A. questions a) Write the molecular formula and draw the molecular struc...

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CHM260 BASIC INSTRUMENTAL ANALYSIS LABORATORY SUMMARY WRITTEN REPORT Name

: MUHAMAD ATIFF BIN MAZLAN

ID No.

:2018232038

Programme :AS120 Instructor

: DR YUSWANIE BT MD YUSOF

EXPERIMENT 3 FOURIER TRANSFORM INFRARED SPECTROSCOPY A. Pre-laboratory questions a) Write the molecular formula and draw the molecular structure of cinnamic acid. C6H5CH=CHCOOH

b) Using the IR table, answer the following questions. i. Predict the location of three peaks you might expect from its spectrum 1700-1725 cm−3 2400-3500 cm−3 1150-1380 cm−3 ii. Indicates bonds were responsible for all the peaks you identified in (i). C=O bond O-H bond

B. Post-laboratory questions a) Explain why a background spectrum must conduct before obtaining the sample spectrum. -The first thing that you need to do is run a background system. This is to ensure that you only get the data from your sample, and not a spectrum containing the other chemicals which are always present. b) Why ‘neat’ liquids, not an aqueous solution, used on salt plates? -First of all, water is a bad solvent because it will dissolve the salt plates. Next, water exhibits a broad -OH peak that will cover up a lot of other peaks that you are interested in. These reasons are strong enough to never use water when taking an IR. C. Answer the following

1. Briefly explain the observation during the preparation of the KBr pellet. It looks homogenous, shiny and fine 2. Name of compound analyzed Benzoic acid 3. The molecular formula of the compound was analyzed. C7H6O2 4. The molecular formula of an unknown compound C8H10N4O2 D. Report summary (1-2 pages) a)

Brief Introduction of the experiment

FTIR spectroscopy is a measurement technique for the collection of infrared spectra. It records the amount of energy absorbed when the frequency of infrared light passes through the monochromator, and the IR light passes through the interferometer. The IR spectra of polyatomic covalent compounds are often more complex, consisting of many absorption bands. The IR spectroscopy was used for both qualitative and quantitative analysis. The IR spectrum of an organic compound provides a unique fingerprint and is distinguished from the spectrum of other compounds. b)

State the experiment methodology

A(i) The KBr metod. 1. A solid sample of benzoic acid and KBr was obtained from the desiccator. The samples were weighed about 1g each and dried in the oven at 110 °C for about 2-3 hours. 2. Agate mortar and pestle were separated from the desiccator so that benzoic acid and KBr were crushed. 3. Approximately 1 mg of benzoic acid was taken and grinded with agate mortar and pestle until it became very small and shiny. 4. Approximately 80 mg of KBr was taken and ground with agate mortar until it became powdered. 5. The two were combined in 1:80 ratio agate mortar and grinded until it became homogeneous. 6. Spatula was used to scrape the mixture in the middle and grinded again for 15 seconds to mix thoroughly. 7. The benzoic acid and KBr reported to be finely grounded because if not, the mixture would disperse the infrared radiation excessively. 8. Spatula was used as a mixture heap in the middle of the agate mortar. (ii) The development of the KBr pellet 1. The die set was removed from the storage container and washed with ethanol. 2. The mixture of benzoic acid and KBr was applied to the die package. The mixture was made to fill the surface of the die set.

3. The die set was tightly closed and placed into the Hydraulic Press gauge and tightened. 4. The Hydraulic Press gauge was pressed until the pressure had risen to 7000 psi. The air had been released and had been left to rest for 2 minutes. 5. The Hydraulic Press gauge was pressed again until the pressure had risen to 8500 psi and the pressure had been released for 1 minute. 6. The die set was opened and the KBr pellet, which was collected, appeared as clear as a piece of glass or a transparent disc. 7. The KBr pellet was placed in the pellet holder for analysis.

A. Preparing of liquid samples ('neat liquids') using the Salt Plate. 1. A 'neat liquid' sample was used. Next, some of the liquid sample was mounted on the plate 2 drops) and covered with another plate. The liquid was designed to cover the entire pan. 2. The sandwich was put in the IR salt plate holder and covered with a holding plate. 3. At least 2 nuts were placed on the holder's posts and gently rotated to hold the plates under even pressure. 4. The holder and the plate were slid into the bracket of the instrument in the sample beam and the spectrum was applied. 5. The salt plates were removed and washed from the instrument using acetone, accompanied by Kim Wipes. The salt plates were then kept in a clean and dry spot. B. Sample Preparation for FTIR (Reflectance) (Reflectance) 1. Solid samples were made to ensure that they were finely ground before use. 2. The spectrum of benzoic acid was based on the Reflectance method. 3. Then an unknown was received from the instructor, and the spectrum was run again.

C. Operation of the FTIR (I) Instrument: Thermo/Nicole 380 FTIR 1. The 'EZOMNIC' programme was being chosen. The 'COLLECT' icon was then selected. 2. 'EXPERIMENT SET UP' was selected to analyse the pellet. 3. The data that appeared in the window has been reviewed. a. No scan: 32 b. Resolutions: 4 c. Final format: Transmittance, Absorbance d. Manage file: Save interferograms e. Context handling: Collect the background of each sample. 4. 'SAVE' and 'OK' have been clicked. The 'COLLECT' button has been picked. 5. 'COLLECT SAMPLE' has been clicked. 6. The title of the experiment was typed and 'Yes' was clicked on it. 7. The OK' button has been pressed to collect the context spectrum.

8. After scanning, the pellet was placed in the sample compartment. 9. Clicked the OK' button to obtain the sample spectrum. 10. 10. 'Find the peaks,' and 'Replace' was clicked after the scan was done. 11.-11. Select 'process,' 'Advanced ATR correction' was selected, 'GE' was clicked and 'OK' was selected. 12. 'Analyze,' 'Install Library,' 'Scan' has been clicked. 13. The result was saved and printed. (ii) Instrument: Perkin-Elmer Spectrum-RX 1. The object was scanned and shifted. 2. The silica gel was removed from the FT-IR. 3. The energy was checked >70% then the stop button was pressed. 4. The scan button was pressed again. 5. The background button was pressed and 3 times scanning was chosen. 6. Execute button then the scan button was pressed. 7. The background button was pressed, then the sample holder was put. 8. The axis was chosen whether X, Y or Z and the background spectrum showed on the screen. 9. The arrows were used to modify the graph: ^˅˃˂ 10. The peaks were marked and the shift V cursor or Shift H cursor were used. 11. Then, the mark was shifted. 12. The plot button was pressed to printout the results. c)

State your finding (spectrum/ functional group) and briefly discuss the finding

From this experiment, two separate samples were used which are benzoic acid and an unknown compound. All were analysed using the KBr pellet and reflectance process. From all the spectra we've used, we've got the functional group from the spectrum seen. Benzoic acid, d)

State the advantages and limitation (if any) of the instrument used as a conclusion.

In this experiment, we can conclude that by using FTIR, we can carry out qualitative analysis of an organic compound such as benzoic acid and ‘neat liquids’. Beside that we can prepare the KBr pellet of an organic compound using solid sample such as benzoic acid into the Hydraulic press gauge for 7000 psi then up until 8500 psi. We can also identify IR absorption peaks and the corresponding functional group of an unknown solid or liquid or powder which the unknown compound was cyclohexane which was C8H10N4O2. e)

Cited

1. BRUKER. O, Accessed on 8th DISEMBER 2020 https://www.azom.com/article.aspx?ArticleID=5958 2. RIZAL. T, Accessed on 7th DISEMBER 2020< https://www.prezi.com/ -f96_3pqwfl_/experiment-3-fourier-transformed-infrared/>...