Saadi Wafae

Liquid-Liquid extraction:

Extraction is the drawing or pulling out off something from something else, Liquid-Liquid Extraction used to remove unwanted components from a mixture according to the two different solubilities of the two immiscible liquids to separate with the unwanted components. In this experiment we are going to purify a sample of benzoic acid contaminated with sodium chloride through liquid liquid extraction techniques.

Results:

The next step was to shake the funnel , then safely remove the gaz.
The mixture this time was completely colourless and they were no grains anymore , everything was dissolved. We couldn’t clearly see were the benzoic acid was the only thing that was remarkable is the two different phase the one on the top was an oil phase composed with ethyl acetate and salt, and the one on the bottom was a aqueous phase composed with water and benzoic acid.
The first extraction is the following step , we had to remove the aqueous part which was on the bottom. We collected the water in a beaker, the extraction part is easy thanks to the fact that we can clearly see the ending of the oily phase and the aqueous phase due to the immiscibility of the organic liquid and the water.
During this step the water collected was still colourless.
Then, a second mix and extract step had to be done. In fact after we re added 10 ml of water and 20 ml of ethyl acetate without adding any salt of benzoic acid .
Du ring this step we saw exactly the same thing as before, two different phases one oily the other aqueous , the water was the bottom phase and the ethyl acetate was the top phase bu this time according to the fact that we didn’t add any of benzoic acid or salt no grain was observable. The mixture was all clear.
All the water part had beed collected , we added slowly 10 ml of Hcl while striking and measured the ph of the solution with a ph paper
While adding the acid chloridric the solution was clear at the beginning but it started becoming white a kind of white precipitate appeared , as we were striking the precipitate faded in the solution. The ph measure equaled 2
The crystallization part was the next step, in fact we took an ice bath and put it in the beaker with all the water collected and waited for 15 mins while striking too. the water and the benzoic acid solution started getting called as I was striking a white film started appearing it was the benzoic acid that started solidifying.
The Next step was the Buchner and vacuum step , after the crystallization we took the water with the white solid we poured it in the Buchner funnel with a filtration paper as the filtration started a white solid , a kind of powder started showing
We collected all the white powder (benzoic acid) , measured the mass of the powder , but also the mass of the filtration paper and the mass of the beaker were we collected it
Mass of the beaker = 41,322g
Mass of the paper+beaker= 41,44g
Mass of the beaker + the benzoic acid relocated + the filtration paper = 44,002g
Mass of the powder (wet) = 44,002-41,44= 2,562g
We dried the collected benzoic acid by putting it for 15 min in the oven with the filtration paper and measured its mass totally dried
Mass of the beaker + filtration paper+ benzoic acid (dry) =43,178
Mass of the final about of benzoic acid = 44,002-43,178= 0,824

Discussion:

During the liquid liquid extraction two phases were observable , as said before the one on top was the ethyl acetate phase and the one on the bottom was the water phase. Water and ethyl acetate are two dismissible components (they cant be mixed) thats why we used them in the liquid liquid extraction, their separation can be easily made.
This extraction technique works well because we have targeted a compound (benzoic acid) that is more soluble in one of two immiscible solvents.
Extraction usually involves shaking a solution that contains the target organic components with an immiscible solvent in which the desired