Can you do IR spectroscopy on a) lemon peel; b) Na gas; c) CO gas? Explain why i

Question

Can you do IR spectroscopy on a) lemon peel; b) Na gas; c) CO gas? Explain why in all cases (3 points) A. How many independent vibrations are there for methane? Show your work. (1 point) B. Are these all going to be IR active? If yes, explain why. If not, provide one example of a vibration that is not going to be IR active. (2 points) 1. 2. . Which transitions are excited by IR radiation? (1 point) 4. What does it mean that a transition is "IR active"? (1 point) 5. Which transitions are IR active? (1 point) 6. A) How many (1 point) and which (1 point) peaks do you expect to see when you look at the IR spectrum of CO2? Explain why. B) Consider one of the peaks that you mentioned in A. Will you actually see the peak corresponding to the pure vibration? Why? (2 points) What is a typical source used to do IR spectroscopy and what kind of radiation does it emit? (2 points) 7.

Explanation / Answer

1) Infrared Spectroscopy technique works on all compounds with covalent bonds (organic compounds) in any state solid,liquid or gas.The technique of introducing the sample ,however, varies for different physical states of the sample.

Liquid samples are pressed between transparent salt plates with salts like sodium chloride ,and beam of IR is passed Solids are generally crushed,a and applied as a thin film in combination with a spreading agent or mulled into a pellet ,while gases can be introduced directly in a lengthy sample cell.

1) Lemon peel has several volatile organic compounds (terpenes) in it .so it can be analysed by IR using specific technique for solid samples

2) Na gas cannot be analysed by IR as it has only sodium atoms but no covalent bonds

3)CO gas has covalent bonds so it can be analysed by IR using specific technique for gas samples

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