to determine the melting point of a solid substance. The melting point of a substance is defined as the temperature at which the substance changes from solid to liquid state. At this temperature, both the phases solid and liquid are in equilibrium. Does the melting point is same for all types of substances? No, it does not. A pure substance has a sharp melting point and it melts at a definite temperature, whereas an impure substance has a lower melting point. It means the termination of melting point is a convenient method to check the purity of the solid substance. How can we determine the melting point? Let us do an experiment to determine the melting point so that you can understand it easily. Aim to determine the melting point of a solid substance. Materials required. Thermometer. 100 ml beaker. Tri-pod stand. Stutter. Thin-volt capillary tube. Stating medium, water or paraffin, wire gauze, etc. Procedure. Poundering the compound and filling of capillary tube. A. The thin-volt capillary tube is sealed from one end by heating it on gas burner for a few seconds. B. The given compound is crushed and it is pushed in the capillary tube in powdered form. The tube is repeatedly tapped and filled by the compound. Fix the tube with thermometer. A. The capillary tube is attached to the thermometer. B. The whole apparatus is arranged as shown in the figure. C. The beaker in which the tube has to be placed is filled with paraffin or water. Heating the liquid bath. A. The liquid bath is heated gently with continuous stirring so that the constant temperature is maintained throughout the liquid using a glass loop stutter moving up and down. As the temperature reaches near the melting point of solid, the flame is reduced and the temperature is allowed to rise gradually. Note the melting point. A. Note the temperature when substance starts melting. The temperature is noted again when the solid melts completely. The average or mean of two values gives correct melting point of the substance. Observations. C-Roll number. Temperature when solid starts melting. T1. Temperature when solidification starts. T2. Average is equal to T1 plus T2 upon 2. Result. The melting point of given solid is X. Degree Celsius. Precautions. The sample solid must be dry. No air gaps must be present in the filled capillary tube. The level of the capillary tube and thermometer must be same. Maintain uniform temperature of the liquid bath. Thank you, Mom. We have understood the experiment very well.