Experiment Melting Point

Melting Point

Introduction:

The first experiment we are doing is the melting point. The melting is very important part of chemistry because it helps identifies the physical properties and reactivity of a compound. Some important characteristics of melting points are that it should be reported as a melting range from lower to upper temperature of the compound. In this lab we will have determine the melting points of known compounds. With that knowledge we will also be given a unknown compound to find.

Purpose:

This experiment has two purposes. The first purpose is to identify the melting point of standard substances to get used to the procedure and the equipment.(learning how to use the mp apparatus). The second purpose is to determine the melting point of unknown substance over the temperature range of interest.

References:

Feiser L.F. Organic Experiments, 2nd ed.; D.C. Heath: Lexington, MA, 1968; 38-42

Equipment:

* The Mel-Temp melting point apparatus

* Capillary tube

Table of Reagents:

See Lab Note Book

Procedure:

See Lab Note Book

Data and Observations:

See Lab Note Book

Conclusion:

After completing the melting point experiment I felt confident about the concepts and hands on part. I felt like the first part of the lab was the most important because you learned how to work the The Mel-Temp point apparatus and thermometer. It gave us hands on experience and knowledge to complete the rest of the lab. My observed range was 79.5 - 81.5 C which a 2 Celsius range was. That was pretty close to the expected range and I continued to the next part.

The next part we had to determine the melting point of pure urea and Cinnamic acid. This part was very similar to the first part. Both pure substances melting points where in the range of what I needed to get. We expected for the urea to be little less than the expected range and in the other hand we expected to have a higher range for Cinnamic acid. I calculated it twice because I wanted to make sure I got used to the machine and see any discrepancy in my results. After we found that we had to make mixtures of the compounds with 4:1. 1:1, and 1:4. This was more difficult because we had to make sure we had divided the substances the right way. After mixing them thoroughly we put them in a capillary tube and inserted it in the machine. The results I got for the mixtures where different. That made sense because there is a different ratio of substance in each mixture. The only one had a question was the 1:1 ration because I expected it to be more in the expected range and it was off by 10 Celsius.

For the unknown we had to measure the melting point for the first time rapidly to get the range. After we got that we had to redo with the last 20 degrees less than 1 C a minute to get the most accurate numbers. I performed this task three times and each time my range was between 2 Celsius which concluded that my unknown was Sulfanilamide. For my last step we had to mix the unknown and the known substance that was given to us before to make sure my assumption was correct. After doing the mixture three times I got the same results concluding that my unknown was accurate.

Melting point is a very important part in chemistry and it is considered a micro technique. We will start with some key concepts of melting point. Melting