Answer to Question #288837 in Organic Chemistry for thomas

Question

1. A vial containing an unknown sample is suspected to be one of the following compounds (mp.): urea (~133 oC), 2,4-dimethylacetanilide (~133 oC), phenacetin (~134oC) or 3-chlorobenzamide (~134 oC). A list of melting points taken on a machine when the 50% of the unknown by volume has been mixed with 50% each of the possibilities is shown in the following table:

2.Three samples labelled R, S, and T possess identical melting points: ~99 oC. When a 75/25 mixture of S and T is prepared, its melting point is 90-95 oC. The melting point of a 50/50 mixture R and T is 79-91 oC. The mp. of a 25/75 mixture of R and S is 97-98 oC. What information does this does this tell you about identity of the 3 compounds? (ie. Which compounds are the same, and which compounds are different? Use only the information you have learned from the slides and your lab manual.) What would you expect as a melting range for a 75/25 mixture of R and T?

Answer 1

1.

Chemical Analysis A scientist wants to identify an unknown compound on the basis of its physical properties. The substance is a white solid at room temperature. Attempts to determine its boiling point were unsuccessful. Using Table 3.6, name the unknown compound.

2.

Here A=78oC,B=213oC,C=100oC,D=oC,154oC have melting points.As stronger the faces of attraction between the particles more will be melting point and vice-versa.Hence,Order of their inter-particle forces of attraction is B>D>C>A maximum melting point, so maximum inter particles forces of attraction.