super quiz 2 - IN LAB BEFORE THE ESTERIFICATION EXPERIMENT...

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IN LAB BEFORE THE ESTERIFICATION EXPERIMENT The quiz will be worth 30 points. There will be 6 questions (MANY of them multi part) 2 questions on TLC, 3 on extraction, 1 question combining TLC or extraction with melting point, recrystallization or distillation. Any items here that is not directly in the notes, make sure to look up in the textbook You will be tested on Esterification along with Aldol condensation on Quiz 6 TLC 1. Precautions to take when preparing for spotting, developing and visualizing impact on observations and results if precautions not followed and reasons for these flawed observations/results. (know what plates would look like) 1. avoid smearing - difficult to obtain Rf 2. Don’t flake of the adsorbent - solvent will not rise 3. Make sure the top is on so solvent wont evaporate 4. solvent below the spotting line so it won’t dissolve the sample Visualization is the process of converting colorless samples (spots) into visible spots. 2. Why pencil needed to mark and why ink is never used The inks from pens are soluble and may separate into their components when exposed to the solvent, and move up the chromatogram. The graphite in pencils is insoluble and will not be changed by the solvent 3. Capillary action definition and how it happens in TLC It is the rate at which each component in the sample moves and it depends on the component's distribution between the mobile and stationary phases It happens when Dipping the capillary into the solvent and when solvent moves up the thin layer chromatography by capillary force. 4. Sample preparation specifics and characteristics of solvents used for preparation and why (impact on spotting as well) 5. What are typical characteristics for solvents used as eluents and why https://www.coursehero.com/file/10826593/super-quiz-2/ This study resource was shared via CourseHero.com
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mixture to be separated must be soluble in solvent more polar means faster polar compound with polar and non polar with non polar mixing of solvents they must be miscible eluent- carrier that moves compounds through the column ○ mobile phase - liquid component of the column (the eluent) ○ stationary phase - tightly packed dry component of the column ○ adsorbent - substance that binds substances to its surface by intermolecular forces LIQUID mobile phase (eluent) A compound that is attracted more strongly to the eluent (mobile phase) will elute first and a compound that is attracted more strongly to the adsorbent (stationary phase) will elute last 6. Characteristics of solvents used with respect to samples use volatile solvent though not very soluble small amount sample is good enough 7. Characteristics of solvents that allow them to migrate rapidly
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