The mixture is dissolved in ethyl ether (common name is ether). Both components are soluble in this solvent. Then a 1 M Noah solution is used to extract the benzene acid in the form of its water-soluble salt, sodium beneath (three extractions to ensure complete removal), leaving the neutral compound in the ether layer. The three aqueous extracts are combined and the two components are recovered as follow: 1 . The neutral compound by washing, drying and evaporating the ether layer. 2. Benzene acid by acidifying the aqueous layer to form benzene acid, which precipitates.
The benzene acid is then recovered by filtration, washed and dried. PROCEDURE: 1 . . 24 grams of unknown sample and 0. 12 grams of benzene acid are weighed and was placed in a test tube. 2. 10 ml ether (very flammable, toxic) was added to the mixture and the test tube was shaded to dissolve the mixture. 3. Then the solution was transferred to the separators funnel and 5 ml of MM Noah was added. It was cap tightly. The layers was mixed by swirling and shaking gently for 30 seconds. 4. Any pressure was vented by tilting the funnel and opening the stop cork. 5.
The stop cork was closed, shaded and again vented. The mixture was held stand to allow the layers to separate. . The top layer was the ether layer and the bottom layer was the aqueous layer. 7. The aqueous layer was drained into an Erlenmeyer flask and it was labeled as first extraction Noah. This is the first extraction step. 8. Another 5 ml of the MM Noah solution was added to the ether layer in the funnel and the procedure was repeated for the second extraction step. The aqueous solution was transferred to another the Erlenmeyer flask and it was labeled as second extraction Noah. 9. Ml HCI was added into each Erlenmeyer flask until the solution is acidic by using blue litmus paper. 10. The solution was to be cooled for about 15 minutes or until it was chilled. 11 . The solid benzene was collected using a Boucher funnel and filter flask. 12. It was washed with some chilled water and the suction was allowed to continue for five minutes to get the solid as dry as possible. 13. Gently a watch glass was scraped and was dried in oven. 14. The solid was weighed and the melting point was obtained. 15. 5 ml of saturated solution of sodium chloride was added to the ether layer in separators funnel. 6. It was caped, mixed, vented and let the layers separate as before. 17. The aqueous layer was discarded. 8. The ether layer was transferred into an Erlenmeyer flask and 1 Goff anhydrous sodium sulfate (drying agent) was added to remove the moisture. 19. The flask was closed, swirled, and stand for 10 minutes. 20. A small dry beaker was weighed while the ether layer is drying. 21 . The dried ether layer was transferred to the beaker with a clean Pasteur filter pipette. 22. The beaker was cooled at room temperature to determine yield of unknown sample. 3. A small amount was scraped and a melting point of the unknown compound was obtained. 24. The melting point obtained of two chemicals given are compared. 25. The unknown auteur compound was determined. 26. The percent recovery by assuming that exactly half of your original mixture was the unknown neutral compound was calculated. 27. The sample was turned in a vial labeled. DATA: Mass Mass of unknown sample: 0. 2403 g Mass of benzene acid : 0. 1202 g Mass of anhydrous sodium sulfate: 1. 0031 g Mass of empty beaker for unknown sample: 66. 976 g Mass of 2 empty filter papers for benzene acid : 0. 6301 g Mass of beaker + unknown sample : 66. 2863 g Mass of 2 empty filter papers + benzene acid : 0. 7503 g Melting point temperature 1st melting point for benzene acid: 125 co Fully melting point for benzene acid: 137 co 1st melting point for unknown sample: 210 co Fully melting point for unknown sample: 245 co DISCUSSION Based on this experiment, the melting point of benzene acid is in range between 125 co- 137 co, while the standard melting point of benzene acid is in range between 121 co – 123 co.
The benzene acid which is in solid form is late to be melt because there are some impurities that still present in the benzene acid. This impurities will react first to be melt before the benzene acid. Although the extraction is known as ‘Washed” a solution of an organic solute in an organic eleven, free of inorganic impurities, the impurities still present. This impurities might not deformed during the process of extraction. This will disturb the reading of melting point of benzene acid.
Maybe some of the apparatus got some impurities and not washed properly, this lead of impurities to the sample. The boiling point of unknown sample is 210 co – 245 co. The other major problems that may happen during this experiment is occur during the degases method. Some of gas not fully released to the atmosphere and still present inside the flask. The swirling and shaking method is not fully handle and lead to the trap of he gas inside the flask. This gas will disturb the next reaction of sample.