De Ocampo, Yves Aaron Julian, Dela Vega, Roderick R. Jr., Elguira, Cedric Tristan D.
Enriquez, Joanne B., Gabat, John Elliot
Group 5, 2D Medical Technology, Faculty of Pharmacy, UST
Sublimation is a change directly from the solid to the gaseous state without becoming liquid. In this experiment, we used the process of sublimation to purify the impure benzoic acid. We obtained from 5.00 g to 2.30 g of the sublimate compound. After we purify the acid we collected the pure and sublimate benzoic acid into two different capillary tubes. The two was then subjected to melting point through oil bath. Melting point is the temperature at which a given solid will melt. The oil bath was ...view middle of the document...
 To calculate the percentage recovery of benzoic acid after sublimation.  To identify the melting points of pure and sublimate benzoic acid through oil bath.
A. Compounds tested (or Samples used)
The sample used in the experiment was a 5.00g of impure benzoic acid, its 2.30g of sublimate and pure. Oil used for determining the melting point temperatures of the compound.
Sublimation was used to purify impure benzoic acid. We used a 5.00 g of impure benzoic acid and put it into a evaporating dish covered in filter paper with holes in it which is sealed with a masking tape. Before putting the evaporating dish on the hot plate we placed a tissue paper in top of it and continuously moistened 10-15 until most of the sample has vaporized. After the sample has been completely vaporized we collected the sublimate in the fume hood and weighed the sublimate for the percentage recovery.
2. Melting Point Determination
The 2.30g of sublimate collected was ground with mortar and pestle. The sublimate’s powder was packed into 3-5 mm capillary tube and the pure benzoic powder in a separate tube. We prepared a iron stand and oil in a beaker for the oil bath. The capillary tubes were attached to the thermometer with a thread, rubber band, or copper wire. It was dipped into the heating oil bath. It was stirred constantly by a copper wire and until the compounds are completely method at a specific temperature.
RESULTS AND DISCUSSION
Sublimation was the process used in the experiment. Impure benzoic acid in the evaporating dish was heated in the hot plate until the compound is form like a crystal like needle which is called sublimate. It is noticed that the benzoic acid did not pass through the liquid phase and went directly into the vapour phase. The sublimate was pre-weighed in a watch glass using a triple-beam balance. The sublimate was grounded using mortal and pestle. The powder was packed in a capillary tube and pure benzoic acid in a separate tube. The collected compound was used in determining the melting point of its temperature using oil bath.
Figure 1. Sublimation set-up
The melting point determination in this...