Pre-Lab: Experiment

Pre-Lab: Experiment three allowed us to use scientific methods to identify the unknown component in the drug Panacetin. According to our lab book, diagram 3.1, indicates that phenacetin and acetaminophen soluble in boiling water, and insoluble in cold water. Which tells that recrystallization can be used to determine the unknown component in Panacetin. This method requires you to boil you substance, and then it will crystallize as its overall temperature cools to lower levels. Keep in mind we measure our substances in Celsius. One key feature that is needed to understand this operation. Solubilities for a majority of substances decrease, as the temperature drops in degrees Celsius. Which means that the freezing or crystallization point, is the temperature at which a substance forms back into a solid after its been melted. We use this method to purify our substances to make sure there is no incorrect residue that can cause errors. A key thing to remember is that impurities lower the melting points of substances. Thus, allowing us to use the given M.P.'s to determine what our unknown substance is. Now, no separation is perfect so, we need to allow an approximate room (~2 Celsius) for non controllable errors. The formula used to determine the amounts of mL required to crystallize our components will be shown in the calculations section. For your convenience, this table below is the lab book's 3.1 table. The structural drawings for our two components are attached to the drawings page.

Substance

M.P.

C.W. Solubility

B.W. Solubility

Acetanilide

114.0 Celsius

0.54g/100mL

5.0g/100mL

Phenacetin

135.0 Celsius

.076g/100mL

1.22g/100mL

Problem: The problem for Experiment three is at stated; "What is the identity of the unknown component of Panacetin?"

Hypothesis: Our purification step showed us that the boiling point of the the purified unknowns boiling point was 1320C. Which is very close to the desired temperature of Phenacetin 135oC. Therefore, I believe our unknown substance is not Acetanilide, and is Phenacetin.

Observations: During the purification step, the unknown started to pop, at a 1220C and completely melted at 1390C. After the compound was crystallized the unknown compound was separated into three different groups to measure boiling points. Since the boiling points of Phenacetin and Acetanilide are different we then added the two compounds to two different groups of the crystallized unknown and left the third group

...