Observed Melting Point Range(°C) Literature Melting Point (°C) Compound Acetanil
ID: 553772 • Letter: O
Question
Observed Melting Point Range(°C) Literature Melting Point (°C) Compound Acetanilide Recrystallization Acetanilide ( Extraction Benzoic acid Extraction p-Chloroaniline Extraction Begins to liquefy Completely liquefied (use any reference material) 114.3 116 114 115 114.3 112 122.41 65 68 72.5 Series 1 Trendline 1 1) Compare the melting points of your samples with the literature melting points. Comment on purity of the samples. (1 point) 2) Comment on the discrepancy (if exists) in melting points for the two acetanilide samples. (1 point)Explanation / Answer
1. In case of Acetanilide obtained from recrystallization, melting point is observed in 116-117°C range which is more than the literature melting point is 114.3°C. This increased melting point is observed because of the presence of salt traces as impurity in the crystal of Acetanilide.
In case of acetanilide obtained from extraction, the melting point is observed same as literature melting point. The melting point shows that acetanilide obtained by extraction is pure and have no traces of salt trapped in the crystals.
The melting points of benzoic acid and p-Chloroaniline are lower than that of the literature Melting points, this is because these compounds are obtained by extraction process and the traces of the solvents are trapped in the crystals.
2. Acetanilide obtained from recrystallization showed higher melting range (116-117°C ) than the literature melting point is 114.3°C because it has salt traces as impurity trapped between crystals and while Acetanilide obtained from extraction showed the melting point as reported in the literature. This is because inorganic salts are not soluble and can not be extracted in organic solvent. Thus the traces of salts as impurity are not found in the crystals and pure crystals are obtained.
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