Objectives
After completing this lab activity, you should be able to,
- Carry out a research-based experiments and identify unknown organic compounds.
- Identify the common organic compounds’ functional groups and determine the structure of an unknown compound using UV/Vis, IR, Mass, and NMR spectroscopes.
- Use Material Safety Data Sheets (MSDS) to obtain information such as molecular formula, physical properties, hazards, and disposal procedures for chemicals used in each experiment.
- Prepare and maintain a laboratory notebook, including a write-up of each experiment that details the purpose, chemical equations, calculation of theoretical yield, percent yield, and record of experimental observations.
- Write clear, concise, scientific laboratory reports using American Chemical Society style for each experiment.
- Use critical analysis skills to interpret data and draw conclusions.
DETAILED INSTRUCTIONS FOR LAB ACTIVITY COMPLETION:
This is a research-based lab. This means that you conduct research online or using the library to identify the unknown compound or missing values from the given information, and then produce a lab report. The lab report should describe how you arrived at your conclusions. Therefore, this lab report may look as follows:
Title: Title of this experiment – There should only be one title for the experiment (“Interpretation of UV, NMR, IR, and Mass Spec. Data – Part 1”).
Method: In this section, you explain the given physical or chemical data for each question (you may number them according to the question number), the instruments used, and their purpose. If the same instrument has been used twice, you need to explain that instrument only once. Then, explain the method you would follow to answer each question.
Analysis: In this section, you show your analysis of the given information for each question.
Results: In this section, you will show your results for each question.
Discussion: In this section, you may discuss the rationale for your solution and what other information would have made your findings easier.
Conclusion: In this section, you detail your results and explain with what percentage of certainty you could confirm your results.
Remember to add any relevant references following the APA format.
You should upload the lab report to the relevant assignment box.
LAB ACTIVITY
Answer all the questions and produce a lab report.
Q.1 The UV spectrum of acetone shows peaks at 280 nm (15) and 190 nm (100).
(i) Identify the electronic transition for each.
(ii) Which is more intense?
Q.2 How could you distinguish between ethanol and acetone using IR spectroscopy?
Q.3 While running a new reaction, a chemist notices the evolution of a gas. A sample of this gas gave a mass spectrum in which the molecular ion (m/z = 44) was the largest ion peak. The only other significant peaks were observed at m/z = 28 & m/z = 16. What is this gas?
Q.4 A liquid compound gave a mass spectrum showing a strong molecular ion at m/z = 156. The only fragment ions are seen at m/z = 127 & 29. Suggest a structure for this compound.
Q.5 The following is a list of solvents used in TLC. Please arrange them in the order of decreasing polarity.
Diethyl Ether
Water
Acetic Acid
Ethyl Acetate
Chloroform
Petroleum Ether
Toluene
Methanol
Methylene Chloride
Cyclohexane
Acetone
ANSWER
Question 1: The UV spectrum of acetone shows peaks at 280 nm (15) and 190 nm (100).
- Identify the electronic transition for each.
The energy gap from π (bonding) to π* (anti-bonding) is higher than the energy gap from n (non-bonding) to π* (anti-bonding). Notably, when the energy gap increases, the wavelength decreases (Okuyama & Maskill, 2013). Energy gap and wavelength……..
- Which is more intense?
The UV spectrum and the energy gap could show the intensity of the transition. Usually, when the energy gap is minimal, there is a more frequent transition that increases the intensity (Okuyama & Maskill, 2013). In the UV spectrum …..To access full answer, click the purchase button below.