A1) Wich compound had a longer retention time? A2) Why did this compound have a

Question

A1) Wich compound had a longer retention time?

A2) Why did this compound have a longer retention time? (Explain your answer considering the STRUCTURES of the two compounds)

A3) How well did the mixture separate? Could you tell the difference between the two compounds? Were they completely separate or did the second one start coming out of the column while the first one was still finishing?

Part A: (Demonstration) A rudimentary GC can be constructed by filling a glas laundry detergent. One end of this tube is connected to the gas line in the lab, and the other end is connected to a Bunsen burner fitted with a piece of copper wire. The laundry detergent acts as the stationary phase, while the methane gas acts as the mobile phase. A syringe is used to inject a small quantity of various chlorine-containing liquids into one end of the tube. The Bunsen burner acts as a detector- the chlorine containing liquid is burned as it exits the tube, and reacts with the copper wire in the flame. This causes the flame to change to a green color. s tube with For this part of the experiment, you will record the time that it takes for dichloromethane (CH2Cl2) and for chloroform (CHCls) to travel through the gas chromatograph (this is called the retention time). Then, a sample containing both liquids will be injected into the GC. Answer the following questions using complete sentence(s) on a separate sheet of paper

Explanation / Answer

A1) Dichloromethane (CH2Cl2) has longer retention time than (Chloroform) CHCl3.

A2) More polar compounds stay in the staionary phase for longer time and hence more polar compound has longer retention time.

CH2Cl2 is more polar than CHCl3. Hence CH2Cl2 has longer retention time.

A3) They have very less difference in their polarity. Ch2Cl2 is slightly more polar than CHCl3. Hence they will not completely separate. Rather a mixture is obtained.

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