Recrystallization and melting point experiment

Extract

[...] Recrystallization and melting point experiment A. Introduction: In this experiment, we purified an unknown substance by recrystallizing it. Then, we determined the unknown substance's melting point and then confirm its identity by mixing with o-Toluic acid, Acetanilide, Benzoic acid, Toluene sulfonamide and Salicylic acid. B. Chemical Responsibility: There are certain dangers and hazards that are associated with this experiment. First, we have to wear safety glasses at all times during the experiment. Then, we have to be careful with the handling of the unknown substance, because either of the substances, Acetanilide, Benzoic Acid, Toluene sulfonamide, o-Toluic acid, and Salicylic acid is irritant, toxic by ingestion or both. [...]

[...] Sample Calculations: Mass of Unknown = Mass of Unknown and Paper Mass of Paper = 3.161 g - 0.942 g = 2.219 g Mass of Crystals Recovered = Mass of Watch Glass and Crystals Mass of Empty Watch Glass = 48.384 g 46.752 g = 1.632 g Percent Recovery for Recrystallization = (Mass of Purified Substance) x 100 (Mass of impure Substance) = 1.632 g X g = Difference in degree Celsius between Mixed Melting Point and Unknown Melting Point: Mixed Melting Point Unknown Melting Point = 140 degree Celsius 139 degree Celsius = 1 degree Celsius Percent Difference between Mixed Melting Point and Unknown Melting Point: (140-139) X 100 = ( 0.5 )(140+139) E. [...]