Acid base extraction

NURHUDA DZULKERNIAN
Experiment One
Title
Acid base extraction.
Objectives
To determine the melting point and percentage of an acid and an unknown.
Introduction
The experiment was conducted to determine the melting point of an acid and an unknown. The extraction are the process of transferring solute from one solvent to another as it usually used to separate one or more components from a mixture.

If two solutes are both soluble in organic solvent for example, a mixture of benzoic acid and naphthalene dissolved in small amount of ether. Add a small amount of dilute NaHCO3 and it will reacts with benzoic acid to form a water soluble salt. The naphthalene remains in the ether.















Apparatus and materials
Test tubes, Buchner funnel, separatory funnel, Erlenmeyer flask, beaker, filter flask, Benzoic acid, Diethyl ether,1M of NaOH, saturated sodium chloride, anhydrous sodium sulphate.
Procedure
First extraction.
1)0.12g Benzoic acid and 0.24g unknown sample was weigh and then they are transferred into a test tube.
2)The mixture was added with 10 ml of diethyl ether.It was shaken until the mixture dissolves completely. 5 ml of 1 M NaOH was added into the solution. The solution was transferred into a separatory funnel.
3)The funnel is then cap tightly and the layer was mixed by swirling the separatory funnel for 30 seconds.
4)The mixture was lefted to allow the layers of the solution to separate.
5)The bottom layer was drained into an Erlenmeyer flask labeled as The First Extraction of NaOH.
Second Extraction.
1)A small dry beaker was obtained.
2)The dried ether layer wasthen transferred into a beaker by using a filter pipet.
3)The ether was carefully evaporated inside the fumehood.
4)The beaker was dried and reweighs after it was cooled at room temperature when all the ether had evaporated.
5)The small amount of dried ether and the melting point was obtained for the chemicals given.






Data
Weight of filter paper = 0.5174g
Actual weight of benzoic acid = 0.1421g
Weight of benzoic acid recorded = 0.0848g
Melting point of benzoic acid = 433.15 K
Percentage recovery of benzoic acid = 59.7 %
Actual weight of unknown sample = 0.3542g
Mass of unknown sample required = 0.3521g
Percentage recovery of unknown sample = 99.4%
Melting point of unknown sample = 387.95 K


Calculation
Benzoic acid
Actual mass of Benzoic acid = 0.1421g
Mass of filter paper = 0.5174g
Mass of original mixture = 0.2187g
Percentage of recovery =( 0.0848g / 0.1421g) x 100% = 59.7%

Unknown neutral recovery
Mass of flask = 45.0634g
Mass of flask + unknown sample = 45.4155g
Mass of unknown sample = 0.3521g
Percentage unknown sample recovery = (0.3521g / 0.3542g) x100% = 99.41%



Conclusion
The melting point of benzoic acid is 433.15 K and the melting point of unknown sample is 387.95 K.
The Percentage of recovery of benzoic acid is 59.7% while the
percentage unknown sample recovery is 99.41%.

References
1)www.nvcc.edu/alexandria/stb/chm/245/45_ex.pdf (22/3/2015, 11.45 am)
2)www.chem.ucla.edu/bacher/special topics/extraction.html (22/3/2015, 11.50am)
3) https://www.google.com.my/search?q=isolating+a+neutral+compound+from+a+mixture+containing+a+basic+impurity&biw=1366&bih=643&noj=1&source=lnms&tbm=isch&sa=X&ei=-GYRVZStBceuuQT4u4CgBA&ved=0CAcQ_AUoAQ#imgdii=_&imgrc=-ByxBZPtSxGQ5M%253A%3BQK2ova04KZJtuM%3Bhttps%253A%252F%252Fwww.thevespiary.org%252Frhodium%252FRhodium%252Fchemistry%252Fextraction_theory_files%252Fextraction8.gif%3Bhttps%253A%252F%252Fwww.thevespiary.org%252Frhodium%252FRhodium%252Fchemistry%252Fextraction_theory.html%3B473%3B509 (23/3/2015, 9.48pm)












Questions
1)Four immiscible liquid other than ether that can be used to extract organic compounds from aqueous solution are toluene, chloride, benzene and hexane.

2)It is wrong to leave a bottle of anhydrous sodium sulphate or calcium chloride open because they are hydrosgopic, the moisture of surrounding will be easily absorbed by them.

3)

Benzoic acid Sodium hydroxide Sodium Benzoate water

The product are easily extracted into water while the original benzoic acid are not so easily extracted into water as they are stable and insoluble in water while the sodium benzoate are ionic. It is very hydrophilic as they are soluble in water.

4)Benzoic acid precipitate out when the aqueous layer was acidified with HCl. Benzoic acid has the hydrogen bonding as it is relatively insoluble in water. The benzoic acid precipitate out as protonated or deprotonated benzoic acid existed. As the acid stronger than benzoic acid is added to the solution, the hydroxyl group is protonated.







5)