Unknown Mixtures Lab Report

Abstract: The purpose of this experiment was identifying two compounds in an unknown mixture via liquid-liquid extraction and acid-base reactions. The compounds in the unknown mixture isolated by using recrystallization, and then their identity was determined by comparing the experimental melting point values with actual melting points. Unknown mixture 5 contained a carboxylic acid, 4-methylbanzoic acid, and a non-ionizable organic compound, 1,2-diphenylethane-1,2-dione.

Purpose: The type of extraction used in this experiment was liquid-liquid extraction, a used technique to separate two liquids in a mixture. In order to do this, the liquids must be immiscible, form distinct layers when mixed. This separation is due to the difference in

Also, due to the fact that carboxyilic acids had a lower pKa than the phenols, means that the extraction using NaHCO3 will only ionize a carboxylic acid since they easily donate a proton. Similarly, when extracted using NaOH the aqueous phase will contain the deprotonated phenols as they are weaker acids and require a stronger base. However, if the mixture contains a non-ionizable organic compound, it will not be ionized and thus stay in the organic phase. This is extracted using NaCl and Na¬2SO4 to dry the solution and then using gravity filtration and the rotovap, the solute is

The solute in beaker 3 was isolated using gravity filtration and the rotovap and massed 0.283g. Due to the fact that there was originally 0.999g of the unknown mixture, it is assumed that half of the mass should have been in each beaker. However, that was not the case and the following percent recoveries were calculated: the percent recovery for 4-methylbenzoic acid was 55.8% and the percent recovery for 1,2-diphenylethane-1,2- dione was 56.6%. The calculated values for the percent recovery show that not all of the original mixture was recovered; reasons, as to why this may have occurred will be discussed