Report – Effect of Temperature on Substances: Change of State – Boiling and Melting Points.
July 3, 2008
Han – Chun, Hou (July 3, 2008)
Partner: Yi, Jiang
The normal boiling point of a liquid can be defined as the temperature at which the vapor pressure of the liquid equals the atmospheric pressure. And the melting point of a compound is defined as the temperature at which both the solid and liquid are at equilibrium. Today we are trying to record the boiling point and melting point by using the materials from the professor, which is one type of unknown crystal and unknown liquid.
The materials were used was including crystal, tap water, test tube, capillary tube, thermometer, rubber band, beaker, weighing paper, and the melting point apparatus. First, we were testing the Melting Point, we got a # 3 unknown crystal from the professor and put it onto the weighing paper. And then we tried to insert some of the sample into the capillary tube by pushing the open end against the compound on the paper. Then we inverted the tube gently tap it on the bench top until it falls to the bottom of the tube. And the we placed it into the melting point apparatus and wait until it reached the melting point, and wait for a minute or two when it cool down, which we recorded 72 degrees. As we compared to the chart from the exercise book, we identified that the unknown crystal was Biphenyl. The next part of this experiment is to test the Boiling Point, we first obtained an unknown liquid from the professor, which is # 24. We then place about 1mL of the unknown liquid into the test tube. And then we set up the capillary tube with the sealed end up inside the test tube. In this procedure, we placed the capillary inside the test tube containing the unknown liquid with a rubber band is wrapped around the thermometer and the test tube. Then we placed it in the beaker which contained of boiling water. And the following step is to wait and slowly heat the water bath. Once the...