Question

Experiment 1: Solids: Recrystallization and Melting Point Learning Outcomes: Upon completion of this lab, students will be able to perform the technique of recrystallization of an impure solid as well as be able to determine an appropriate solvent to use for recrystallization. Students will also be able to determine the approximate purity of a solid organic compound by performing melting point analysis as well as confirm the identity of an unknown solid compound by performing a mixed melting point with an available standard. Introduction In chemistry, recrystallization is a technique used to purify solid compounds. By dissolving both impurities and a desired compound in an appropriate solvent, either the desired compound or impurities can be coaxed out of solution, leaving the other behind. It is named for the crystals often formed when the compound precipitates out. Crystalline solids are typically a much more pure when compared with amorphous solids. This is because a crystal structure is a unique arrangement of atoms, ions or molecules that can be described as a highly ordered structure, occurring due to the intrinsic nature of its constituents to form symmetric patterns. Read more about Solvents and Recrystallization in your laboratory technique manual (page 121-129). In the lab it is often necessary to determine the identity and analyze the purity of a compound. One technique that can be used for this purpose is Melting Point Analy melting point analysis in your laboratory technique manual (page 49-52). sis. Read more about In Part A of this experiment, you will be learning the techniques of recrystallization and melting point analysis by purifying, and analyzing the resulting purity, of an initially impure sample of Benzoic Acid. In Part B of this experiment, you will be assigned an It will be necessary to test the solubility of this compound to determine an appropriate for recrystallization. In Part C of this experiment, you will purify your unknown b recrystallization and determine the identity by mixed Melting Point analysis with a series of possible knowns that will be made available to you. unknown organic compound solvent Procedure: Safety Concerns 1. Wear safety goggles while performing the experiments. ing in vapors and of your body that come in contact with 2. Perform experiments in a laboratory hood. Take care to avoid getting chemicals on your skin. Wash any areas any chemicals with soap and water Use a hot plate (no flames) to heat solutions as most solvents used for recrystallization are flammable. When using a hot plate, do not set it at its highest value. A 3. moderate Page 93

Please right an in depth discussion about part C. We we’re not able to get any recrystallization from our unknown. Talk about possible failures that could of happen that prevented us to not get any or our unknown to recrystallize. Thanks so much!

Answer 1

You have given an unknown sample to find its melting point and recrystallization the unknown sample is maybe impure you have to purify the compound and find its melting point of the pure and recrystallize the pure compound unknown compound is impure which contain some impurities some of these impurities will dissolve and some will not

Take your small amount of unknown compound in a test tube with a suitable solvent and shake this mixture at room temperature if this sample mixture of unknown compound is soluble to large extent at room temperature done the unknown sample is soluble in that solvent it is important for a sample to dissolve in that solvent to find the required result

For your experiment in the given unknown sample you have to take a solvent a suitable solvent and dissolve this unknown compound in that solvent if it's not completely soluble then heat it on a water bath pure compound and impurities in that unknown sample is dissolved in that solvent we have to heat this reaction mixture on water bath to a concentrated stage and than cool it on an ice bath the compound will recrystallized upto that concentrated solution or solution will recrystallized separate that recrystallized crystals and find the melting point

The problem occur in this experiment is either due to the solvent for which we are taking for the recrystallization we have to take a suitable solvent for that unknown sample so that it is either completely dissolved or springly dissolve to find the result .we have to take so many precautions because it is a sensitive process either very high temperature may not give recrystallization the precautions we kept in mind to give result

hope u get it