Introduction to melting point determination experiment





Tear off rough determination edges.
The mixture will be heated in a determination hot sand bath until the determination solvent begins to determination boil.
An unknown sample labelled 4 was obtained and its melting determination point was determined using the Mel-Temp.
You should be able to obtain melting point ranges of four degrees or less with the upper temperature of the range within two degrees of the literature values given above.In the first part, you will determine the melting point range of three known compounds.Insert the capillary tube, closed end down, into the slot between the observation port and the thermometer chimney point on the Mel-Temp.Define or explain: melting point, melting point range, phase transitions, and eutectics.If the mixture of acetanilide, water, and decolorizing pellets was not boiled long enough, there would still be left over impurities and some portion experiment of acetanilide would still be impure and would not yield the expected amount of crystals.And also to analyze the effects of impurities in the melting point range /p p of a substance.p p Melting points are often used to distinguish and differentiate organic and inorganic /p p compounds and to measure their purity.Place melting a tiny sample of the compound whose melting point is to be determined on a piece of weighing paper or a watch glass.During the first trial, which was the fast trial, the temperature of the Mel-Temp was raised about 10-20 C per minute and the unknown had a melting point of 104.Benzoic Acid /p.There were many sources of potential error, so again it is highly unlikely to recover that original amount of trans -1,2-dibenzoylethylene present in the impure sample.The will calibrate the machine, and then an unknown compound will be identified by discovering its melting range using the technique of mixture-melting points.The results from the second part of the experiment seemed accurate. Rank the following compounds in decreasing melting point: benzoic acid, manager naphthalene, /p p salicylic acid, and urea.
Experimental Procedure The first part of the experiment is the recrystallization of impure acetanilide.
This takes standing some simulator organization, but saves much of time.
p p In this second experiment, there is an unknown substance and determined expand its melting /p p point.The sample will then be transferred to a Craig tube.Next,.5 mL of 95 ethanol will be added using a pipet pump and 2 mL graduated pipet along with a wood boiling internet stick.The group was /p p hesitant of the results because there was still acrobat a little amount of sample that was not melted and /p p because the hot plate was defectivethe electric cord is loose, interrupting the heating process.Do not place any into mouth.After the acetanilide standing dissolved, the Erlenmeyer flask was removed from the heat and 25 mL of cold water and about.5 g of decolorizing carbon pellets were added to the flask.The temperature at which all the /p p crystals liquefied was 132C which is closest to Urea.An additional.5 grams of decolorizing carbon pellets can be added if the blue color has not been completely removed.The crystals are to then air dry, and the starting and ending weights are to be measured.Do not heat it beyond the capacity of the thermometer (210 o C).The filtrate could not have been allowed to cool long enough and some crystals might not have formed.The amount should be enough to fill the tube to a depth of about one millimeters.1 Determination of Melting Points This experiment consists of three simulator parts.





The initial melting point obtained /p p was 115C and the temperature introduction to melting point determination experiment in which all of the sample melted was 120C.
Mixed Melting Point Determination Select the three compounds closest in temperature to your unknown.
The sample should fall to the closed end.

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