Experiment-1
Object – To determine the melting point of given organic compound.
References:
- Vogel Arthere, Elementary practical organic chemistry, 2nd edition, 1966, published by CBS publisher, page No. 3-12.
- Agarwal O.P., Practical Organic chemistry, published by Krishna educational publisher, Edition 2014, page no. 60-64.
Requirements – Given Solid Substance, Capillary Tube, Melting Point apparatus.
Theory-
The change from solid to liquid state of a compound in heating is called melting and the temperature at which a solid in its pure form melts is called the melting point. Every pure solid has a characteristics melting point therefore determination of melting point helps in identification of the compound.
Presence of impurities lowers the melting point of the solid. Thus Melting point also serves as a criterion of purity of a compound.
Procedure-
- Take a fine capillary of length 5-6cm.
- seal its one end by inserting the end of the capillary tube horizontally into the extreme edge of a small steady Bunsen flame for a few seconds, rotating the capillary mean while.
- Take a small quantity of the compound whose melting point is to be determined in mortar pestle and powder it.
- Introduce the powdered compound in the capillary tube.
- Gently tap the capillary tube so that the compound sinks into the closed end.
- Repeat the procedure of introducing and tapping three to four times.
- Put the capillary in digital melting point apparatus.
- observe the temp. at which it start to melt.
- Finally note the temp. at which it completely melt.
Observations–
Melting point
1 ……………………0C
2 ……………………0C
3……………………0C
Mean Melting point = (t1+t2+t3)/3 0C
Result: The melting point of the given organic compound is…………………………………….
Precaution-
1. The capillary tube is filled one third of its length.
2. The rate of heating should be controlled.
3. It should be very slow near the melting point so that the melting point can be recorded accurately.
Melting point of some common organic compounds
Phenol : 42
α-Naphthylamine: 50
α-Naphthol : 96
Acetamide: 82
β-Naphthol: 123
Benzamide: 128
Oxalic Acid: 101
Urea : 132
Benzoic Acid : 122
Fructose : 103
Cinnamic Acid : 133
Glucose : 146
p-Toludine: 43
Sucrose: 186
Naththalene : 80
Acetanilide : 114.3