PHYSICAL PARAMETERS
1.9.1: Melting point- A pure crystalline organic compound has a definite and sharp melting point, that is, the melting point range (the difference between the temperature at which the sample collapse or at which the sample becomes completely liquid) does not exceed above 0.5oC. If any miscible or partially miscible impurities are present in small quantity it will increase the melting point range and cause the initiation of melting to occur at a temperature lower than the melting point of the pure substance. The melting point of a solid is the temperature at which it changes state from solid to liquid at atmospheric pressure. At the melting point the solid and liquid phase exists in equilibrium. The melting point of substance depends on pressure and is usually specified at standard pressure. But when temperature is reverse changes from liquid to solid, it is referred to as the freezing point or crystallization point.4
1.9.2. pH - pH is a measure of the acidity or alkalinity of a water solution. The acidity or alkalinity of a water solution is determined by the relative number of hydrogen ions (H+) or hydroxyl ions (OH-) present. Acidic solutions have a higher relative number of hydrogen ions, while alkaline (also called basic) solutions have a higher relative number of hydroxyl ions. Acids are substances which either dissociates (split apart) to release hydrogen ions or react with water to form hydrogen ions. Bases are substances that dissociate to