Posted by Natasha on .
I am about to do an extraction experiment, and needed help with a question to improve my understanding. Any help appreciated.
1. You have 150 ml of a solution of benzoic acid in water estimated to contain about 5g of the acid. The distribution coeffcient of benzoic acid in benzene and water is approx. 10. Calculate the amount of acid that would be left in the water solution after three 50 ml extractions with benzene. SO the same calculation using one 150ml extraction with benzene to determine which method is more efficient.
Also I was wondering why three small extractions are more efficient than one large extraction, and how can this be proven?
a. The main reason that three extractions are more efficient than one large one is that the first extraction takes out a portion, the second extraction STARTS with less than the first and the third extraction starts with even less. It's the same process as transferring a solution quantitatively from one beaker to another. You can fill the beaker with water and pour into the other beaker with one transfer OR you can wash with four or five 5-mL portions and pour each rinse into the other beaker. You will get quantitative transfer (meaning all of it) with four or five SMALL rinses but you will not get quantitative transfer with just one large (or small) rinse.
b. The way you prove this is to do it.