Acid-Base Extraction. Essay

Topics: Solvent, Sodium hydroxide, Chemistry Pages: 4 (1295 words) Published: April 7, 2013
1. To separate a mixture of an acid and a neutral compound into its component by extraction. 2. To determine the melting point and the yield of the benzoic acid and the unknown sample. 3. To determine the unknown sample whether is is Trimethylmethanol or 1,2,4,5-Tetrachlorobenzene. Introduction

Extraction is a process of transferring a solute from one solvent to another. It is usually used to separate one or more components from a mixture. Diethyl ether, dichloromethane (methylene chloride), trichloromethane (chloroform), pentane, hexane, petroleum ether are some of the solvents commonly used for extracting aqueous solutions. Petroleum ether and ligroin are mixtures of hydrocarbons whereas the other liquids mentioned earlier are pure substances. The most excellent liquid for extracting organic solutes is diethyl ether. Ether is chemically very stable, has a low boiling point and is an excellent solvent for most organic compounds. In this experiment, a mixture of benzoic acid and a neutral compound ; triphenylmethanol or 1,2,4,5-tetrachlorobenzene is separated into its components by the process so called extraction. The mixture is dissolved in diethyl ether. 1 M of sodium hydroxide, NaOH solution is used to extract the benzoic acid in the form of its water soluble salt,sodium benzoate,leaving the neutral compound in the ether layer. The three aqueous extracts are combined and the neutral compound are recovered by washing, drying and evaporating the ether layer whereas the benzoic acid are recovered by acidifying the aqueous layer to form benzoic acid which precipitates. The benzoic acid is then recovered by filtration,washed and dried.

0.24 grams of unknown sample and 0.12 grams of benzoic acid were weighed and placed in a test tubes. 10 ml ether was added to the mixture and the test tube was shaken to ensure that the mixture was homogenous. The solution was then transferred to the separatory funnel and 5 ml of 1 M NaOH was...
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