Introduction:
Melting point is loosely defined as the temperature at which a solid becomes a liquid. In chemistry, melting point, also recognized as the liquefaction point, refers to the temperature at which the solid and liquid phases of a compound are equal. Melting points are used when deciding the purity of a substance. Purity of a compound is found by finding the melting point range and comparing it to the literature value and can only vary from 1 to 2 °C. If a substance is to be more than 1 to 2°C, then it is considered impure. An effective way to find a melting point of a compound is to grind the compound into a fine powder and placing it in a very small tube, a capillary tube, and then melting it in a Mel- Temp model. To ensure that the range is correct, once the temperature of the compound is close to the literature value, then heating process should be slowed down to 1 °C per minute for accurate results. The way to record the range is by using the temperature at which the first droplets are seen and then when the compound is fully melted. Not all substances behave the same way when melted, some have unusual occurrences. Some substances such as tartaric acid decompose while melting or before melting but not all. When a substance decomposes, there is a distinct color change to a brown or black and is recorded by placing a “d” or “dec” after the melting point range. Reaction: None Physical Data1,2: Compound MW (g/mol) MP °C BP °C Density (g/mL) Solubility Hazards Acetaminophen 151.16256 169-172 >500 1.26 Alc, meth, eth Toxic Tartaric Acid 150.08684 171-174 NA 1.49 NA Irritant Phenacetin 179.21572 134-136 242-245 1.10 Ace, Benz, Pyr Toxic Apparatus: Calculations: None Results and Observations: Compound Experimented Value MP°C Acetaminophen 154.2 – 155.8 Tartaric Acid 156.2 – 157.1 Phenacetin 123 – 124.7 9:1 Mixture 109.9 – 121.2 Unknown 153.3 – 154.2 Unknown + Suspect 154.3 – …show more content…
The small ranges of the acetaminophen, phenacetin, tartaric acid, and the unknown proves that they were pure while the mixture had a wide range which proves the effect of the impurity of a compound of temperature.
The overall results were not as expected due to the calibration of the apparatus being off. The apparatus was reading temperatures lower than what they actually were leading to our data having lower melting points. The experiment would have had a better outcome if the equipment worked properly as well as having lower amounts of the compounds into the capillary tubes. The procedure was a very good method for finding the purity and melting points of compounds due to the easy at which the melting is noticed as well as being able to control the temperature unlike using a Bunsen burner or a hot