Measurement of Physical Properties
Autor: tsmith12893 • October 2, 2016 • Lab Report • 937 Words (4 Pages) • 981 Views
Experiment 1: Measurement of Physical Properties
PURPOSE:
All organic substances contain certain classic physical properties, which can be used to differentiate them. Specific experimental techniques are used to measure these properties, which include density, refractive index, and boiling points for liquids, and melting points for solids. Although these values can be found through sampling techniques, the literature values can be located using online resources and chemical handbooks such as the CRC Handbook of Chemistry and Physics and the Aldrich Catalog online.
For this experiment, the melting points of pure acetanilide, pure caffeine, and mixtures containing both substances will be found using a melting point apparatus. The densities of dichloromethane and ethyl acetate will be determined using the syringe method of measuring densities. Lastly, the refractive index of methanol will be determined using a refractometer. All values found will be compared to the literature values.
TABLE OF CHEMICALS:
Table 1: Chemicals and their Properties
Chemicals | Boiling Point | Melting Point | Density (@20°C) | Refractive Index |
Acetanilide | 304°C | 114.3°C | 1.22 g/cm3 | 1.576 |
Caffeine | 178°C | 238°C | 1.23g/cm3 | 1.49 |
Dichloromethane | 39.75°C | -96.7°C | 1.326g/mL | 1.4241 |
Ethyl Acetate | 77.1°C | -83.6°C | 897kg/m3 | 1.372 |
Methanol | 64.7°C | -97.6°C | 792kg/m3 | 1.3284 |
PROCEDURE:
Melting Point
Using melting point tubes, small samples of pure acetanilide and pure caffeine were collected and put into two separate tubes. Then combinations of 75% caffeine-25% acetanilide, 25% caffeine-75% acetanilide, and 50% caffeine-50% acetanilide were collected and placed into three separate tubes. The melting point apparatus was set up and usually contains three slots for the tubes to be inserted, however, one of the slots on the particular apparatus used was broken, so only two tubes could be inserted. First, the pure samples were inserted and their melting points were determined and recorded after the apparatus was heated to the perspective melting points. Secondly, the temperature on the apparatus was lowered, allowing the samples to cool and crystalize again. Once crystallization occurred, a second melting point was observed. Lastly, the melting points of the three mixtures were observes and recorded.
...