1. In this experiment we injected the sample to be analyzed by Gas Chromatograph
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Question
1. In this experiment we injected the sample to be analyzed by Gas Chromatograph equipped with an FID (Flame Ionization Detector). The detector ionizes the sample as it reaches it, and the peak is proportional to the number of ions with a live flame. A chemist performed a distillation of methanol and water and wanted to analyze the results using the same GC instrument with FID. Could he use a similar procedure to analyze the results of his experiment? Explain why yes or no?
2. Ethylbenzene and o-xylene can be separated and analyzed using GC without injecting anequimolar standard to a high accuracy. Explain why that is the case for these two compounds while we had to inject an equimolar solution for our experiment.
3. The separation of two liquids on the GC is very similar to the distillation process.Compare the two methods describing the process while pointing out to the similarities and differences between the two methods
Explanation / Answer
1. A chemist may use the same method for the analysis of methanol and water by GC. Both water and methanol vaproizes and then ionizes in the FID. The peak intensity would be proportional to th number of ions. Both giving 2 ions each can be quantified easily.
2. Ethylbenzene and o-xylene both have the same molar mass. So any mixture weight would have an equal amount of both in it. Also they both would ionise in the same fashion. thus analysis of them would be easily possible even when the mixture injected is not equimolar. On the other hand in the experiment cyclohexane and toluene are two very different compounds. Both with different molar masses and ionisation of it to form ions would also be very different. One being aromatic and the other being the non-aromatic species. Thus. to have an accurate analysis we have to know how much we injected in the GC and must be close to equimolar mixture.
3. The separation of two liquids is very similar on the GC as like distillation. In both the cases the more volatile fraction would come off first followed by the less volatile fraction. the main difference between the normal distillation method and the GC is the limitation of the amount of sample and recovery. In distillation we can have any amount of liquid separation possible whereas, in GC only small amounts of liquid can be separated. The liquid injected is not recoverable whereas distillation main purpose is to separate and use the the liquid further for reactions.
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