A piece of filter paper in the beaker during TLC elution is necessary to provide

Question

A piece of filter paper in the beaker during TLC elution is necessary to provide the saturated vapors of eluant in the beaker. The following scanned TLC plates were made at exactly identical conditions (the same set of substances, same eluant, same brand of TLC plates and so on) except that the left one was eluted with no filter paper in the beaker:

Conte, × GApiec × Be My Bla ::: Apps × Course × Organ × Meet Recen × Kent S × Home >x https:/ learn.kent.edu/bbcswebdav/pid-5966309-dt-content-rid-54057783-1/courses/1 1743.20 1680/30475%20Fall%20201 6%20sec%20001%2C%20002%2C%2001 Dell Imported From 1E Results Q Exam 2; Ch 15: Nervo Other bookmarks Organic Chemistry Laboratory 35 38 The front of the solvent This plate was eluted in a beaker with no filter paper inserted. This plate was eluted in a beaker with a piece of filter paper Elution time 20 min Elution time 5 min (this is a colorless substance. The spot was visualized under UV and marked with a pencil) The starting line the mixture was applied there) Explain (3-5 full sentences) what happened. ENG 2) Your were using pencils to mark TLC plates. Why it is usually not wise to use any kind of ink filled "writing devices" such as ball pens, capillary pens, markers, etc.? Explain (2-4 complete sentences) what would happen in this case 12:00 AM

Explanation / Answer

Filter paper placed in the solvent provides more surface area for faster solvent evaporation. This creates more solvent vapour in the TLC chamber, which is widely desired. Here, the mobile phase moving over the stationary phase doesn’t dry quickly during the process, resulting in a less elution time. This is the reason for the higher elution time in TLC plate 1, where no filter paper is used

The ink form ball pen or ink filled devices may also dissolve in the solvent and move along with the compound on the TLC plate. This will produce false results. However, the pencil graphite won't dissolve in the solvent and hence it can be used to safely mark on the TLC plate

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