Melting Point Determination
Chris Diaz and Jay Lee
January 26, 2015
Organic Chemistry

Purpose: The purpose of the experiment was to use a Mel-temp apparatus in order to determine the melting point of several compounds. The melting point was used to identify several known compounds and utilize those results in order to determine the identify of specific unknown compounds. Also, mixtures of compounds were also used in identifying unknown compounds and they were also analyzed to gain an understanding on how impurities may affect the melting point of these compounds.

Procedure: The experiment was divided into 3 parts with their own respective goals involving melting point. For part 1, 9 samples were provided and the objective was to record the melting point/range of all of the individual samples using a Mel-temp apparatus. Individual capillary tubes were used to collect a sufficient amount of sample (the particles are visible at the closed end of capillary tube) and placed into the 3 slots of the Mel-temp apparatus. The Mel-temp was set to a power level of 2-3 in order to keep a steady rate of 2 degrees per minute. Each capillary tube was then analyzed until 2 measurements were collected. The first measurement was known as “T1” which was the starting melting point where the first crystal begins to melt and the second measurement known as “T2” was when all of the crystals became one uniform liquid. One observation that was noted in the experiment involved the compound 2-Nitrobenzaldehyde’s crystallized state being a clear color, but then melting into a light-green liquid. This compound was unique in comparison to the other compounds that liquified into a clear color. After all of the compounds were tested, the apparatus was cooled using an air ventilation system that was available in the lab.

For part 2 of the experiment, a sample of a mixture was heated and its melting point was determined. The mixture that was randomly selected consisted of 60% Trans-cinnamic acid and 40% Nitrobenzaldehyde.

In part 3, an assigned unknown compound was placed in a capillary tube and placed into the Mel-temp to find its melting point. The melting point of the unknown seemed to be higher than what was expected as the crystals remained solid for approximately 2 minutes so the rate of mel-temp was slightly