During this experiment you mo asked to dissolve a small amount of your purified
ID: 1003233 • Letter: D
Question
During this experiment you mo asked to dissolve a small amount of your purified crystals. In ethyl acetate to create a spotting solution for TLC analysis What would the effect be on the Rf value in you accidently used ethanol instead of ethyl acetate during this step? the Rf value would be zero Decrease the R_f value No effect on the Rt value Increase the Rf value Benzydrol will be recrystallized from hexane during tins experiment. Please identify the following statements about recrystallization as true or false. Select nil that are true Start heating the flack with just enough solvent In the flask to cover the sample. If everything In the sample dissolves m the hot solvent, it is still necessary to carry out s hot gravity filtration to ensure a pure final crystal If you are short on time. It Is okay to place the hot recrystallization solution directly into an ice water bath At room temperature, slowly add solvent until all of the sample dissolves When you collect your crystals you can wash them with a small amount of the recrystallization solvent, but you should cool the solvent down in an ice both before using it. A bolling aid is not required. During a hot gravity filtration you must use a flute filter paper and a stemless funnel.Explanation / Answer
3.
(a) If accidentally the student has used ethanol instead of ethylacetate, the effect of the resulting Rf would be,
Increase the Rf value.
Ethanol is more polar and thus compounds on the tlc plate would move higher.
(b) Benzydrol recrystallization from hexane.
Flask is heated with sufficient solvent to cover sample : True
If everything dissolved in hot condition, we still must do a gravity filtration : True
If in hurry it is ok to cool the hot flask in ice bath : False
At room temperature solvent is added to dissolve sample : False
When filtering crystals, washing with cold recrystallization solvent is done : True
A boiling aid is not required : False
Filtration is done using flutted filter paper : True
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