Suppose that a compound Z had a partition coefficient of 8 in ether-water. If 10g of z was dissolved in 100mL of water, and if the water solution was extracted with two 100 mL portions of ether, answer the following questions

a) what is the total amount of z contained in 200mL of ether extract after the two extractions?

b) if instead of using two 100 mL portions of ether a single extraction had been carried out using one 200 mL portion of ether what weight of Z would be contained in the ether solution under these conditions?

Yeah, Bob is wrong.

What you would actually do for the following:

a) Do the first extraction:
K=(z/?mL ether)/((10g-z)/?mL water)...so
8=(z/100mL ether)/((10g-z)/100mL water)

Rearrange to make it easier:
8=(z/(10g-z))*(100mL water/100mL ether)

Now solve for z and it should come out to about 8.9g. (Simple algebra shouldn't be too hard)

Then do the same thing for the second extraction, but instead of (10g-z), replace it with (1.1g-z) because that's the amount of Z that remains in water so you're using ether again to extract the remaining z.

8=(z/100mL ether)/((1.1g-z)/100mL water)
8=(z/(1.1g-z))*(100mL water/100mL ether)
and then solve for the second z value.

Finally, add both Z's from both extractions and you should get your total Z extracted.

b) Use the same equation from the first part:
K=(z/?mL ether)/((10g-z)/?mL water)
8=(z/200mL ether)/((10g-z)/100mL water)
8=(z/(1.1g-z))*(100mL water/200mL ether)
then solve for z only one time because you're using all 200mL ether to extract in one go, so when you get your z, that will be the answer.

Guys I think you're a little late

I think you're wrong bob.

Pee Pee POo Poo

To answer these questions, we need to understand the concept of partition coefficient and how it influences the distribution of a compound between two immiscible solvents, like ether and water.

The partition coefficient (P) is defined as the ratio of the concentrations of a compound in two immiscible solvents at equilibrium. In this case, the partition coefficient of compound Z in ether-water is given as 8.

a) To determine the total amount of Z contained in 200mL of ether extract after two extractions, we first need to calculate the amount of Z extracted in each extraction.

Given that 10g of Z was dissolved in 100mL of water, we can calculate the concentration of Z in the water solution:
Concentration of Z in water = Mass of Z (10g) / Volume of water (100mL)

Next, we need to consider the partition coefficient to determine the concentration of Z in the ether phase after extraction. Since the partition coefficient is defined as the ratio of concentrations, we can set up the following equation to calculate the concentration of Z in the ether phase after one extraction:
Concentration of Z in ether = Partition coefficient × Concentration of Z in water

After the first extraction, we have 100mL of ether. Therefore, the total amount of Z extracted in the first extraction is:
Amount of Z extracted in the first extraction = Concentration of Z in ether × Volume of ether (100mL)

Now, we can apply the same process for the second extraction using the remaining 100mL of ether.

Finally, to calculate the total amount of Z contained in 200mL of ether extract after the two extractions, we add the amounts obtained from the first and second extractions.

b) If a single extraction had been carried out using one 200mL portion of ether, we would follow a similar procedure as in part (a), but considering the different volume of ether.

First, we calculate the concentration of Z in the water solution using the given information. Then we can determine the concentration of Z in the ether phase after extraction using the partition coefficient.

Finally, we multiply the concentration of Z in the ether phase by the volume of ether used (200mL) to obtain the weight of Z contained in the ether solution under these conditions.

Remember to convert the concentrations and volumes to consistent units before performing any calculations.

By following these steps, you should be able to answer both questions and understand the process behind it.

a)

K = 8 = (z/100)/(10/100)
Solve for z for the first extraction, subtract from 10 to determine the amount left in the aqueous phase, then repeat the extraction.
b) is done the same way.