Pre Lab Melting Point 1 List six physical properties of orga

Pre Lab Melting Point

1 List six physical properties of organic compounds that are often measured by organic chemists in attempting to identify a compound. 2. Melting point determination can be used for several purposes. What are those purposes? 3. Define the following terms: a) melting point b) sublimation c sintering d) eutectic mixture- 4. What is the effect of a small amount of impurity on the melting point of an organic compound? 5. What is the difference between the capillary melting point and true melting point?

Solution

Solution(1):

1) To check if a pure enantiomer, specific rotation

2) ultraviolet-visible absorption spectrum

3) infrared absorption spectrum

4) Melting and boiling point

5) Refrective index

6) Elemental analysis ( To find out % composition of C, H, N, ...)

Soluution(2):

the purpose for finding out Melting point are given below..

1) It gives an idea of elements

2) To help determines it\'s general purity. (smaller the melting point range means more purity)

Solution(3):

a) Melting Point: The melting point of solid is defined as the temperature at which the solid exists in equilibrium with its liquid under an external pressure of one atmosphere.

b) Sublimation: Sublimation is the phase transition of a substance directly from the solid to the gas phase without passing through the intermediate liquid phase.

c) Sintering: Sintering is the process of compacting and forming a solid mass of material by heat or pressure without melting it to the point of liquefaction.

d) Eutectic Mixture: A eutectic mixture is defined as a mixture of two or more components which usually do not interact to form a new chemical compound but, which at certain ratios, inhibit the crystallization process of one another resulting in a system having a lower melting point than either of the components.

Solution(4): The melting points of compounds may be lower than the reported values because it may contain small amounts of the impurities or solvents. Impurities in a solid cause a melting point depression because the impurity disrupts the crystal lattice energies. This is called a freezing point depression.