.070g caffeine dissolved in 4 mL water. caffeine is extracted from aqueous solution 3 times with 2mL portions of methylene chloride. calculate total amount of caffeine that can be extracted into the 3 portions. caffeine has a distribution coefficient of 4.6 between methylene chloride and water
There are two ways to do this.
1. Ko/a = concn organic/concn aq and do that three times, taking the answer from the previous extraction to use for the new extraction.
2. Or you can do all of it at one time with
fn = [(1 + Kd*(Vo/Va)]-n where fn = fraction solute REMAINING in the aqueous layer. o=organic layer; a = aqueous layer; concn can be in g/mL; Vo=Volume in organic layer; Va = volume in aqueous layer.
Post your work if you get stuck. If you want the portion in the organic layer, just use the second method to find the fraction in the aq layer and subtract from 1 to find the fraction in the organic layer.
To calculate the total amount of caffeine that can be extracted into the three portions of methylene chloride, we need to consider the distribution coefficient and the amount of caffeine initially dissolved in water.
1. Calculate the total amount of caffeine initially dissolved in water:
- Given that 0.070 g of caffeine is dissolved in 4 mL of water.
- Convert the amount to moles by dividing by the molar mass of caffeine (194.19 g/mol):
0.070 g / 194.19 g/mol ≈ 3.60 x 10^-4 mol
2. Calculate the amount of caffeine that can be extracted into each portion of methylene chloride:
- Given that each portion of methylene chloride is 2 mL.
- The distribution coefficient for caffeine between methylene chloride and water is 4.6.
- To find the amount of caffeine extracted in each portion, multiply the initial amount of caffeine by the distribution coefficient:
3.60 x 10^-4 mol x 4.6 = 1.66 x 10^-3 mol
3. Calculate the total amount of caffeine extracted into the three portions:
- Since there are three portions of methylene chloride, multiply the amount of caffeine extracted in each portion by the number of portions:
1.66 x 10^-3 mol x 3 = 4.98 x 10^-3 mol
Therefore, the total amount of caffeine that can be extracted into the three portions of methylene chloride is approximately 4.98 x 10^-3 mol.
To calculate the total amount of caffeine that can be extracted into the 3 portions of methylene chloride, we need to consider the distribution coefficient and the initial amount of caffeine in the water.
Let's first calculate the initial amount of caffeine in the water solution:
Initial amount of caffeine = 0.070 g
Next, we need to calculate the amount of caffeine that can be transferred from the water to each portion of methylene chloride. The distribution coefficient tells us the ratio of the concentration of caffeine in methylene chloride to the concentration in water.
For the first portion:
Amount of caffeine extracted = distribution coefficient * volume of methylene chloride used
= 4.6 * 2 mL
= 9.2 mL
For the second portion:
Amount of caffeine extracted = distribution coefficient * volume of methylene chloride used
= 4.6 * 2 mL
= 9.2 mL
For the third portion:
Amount of caffeine extracted = distribution coefficient * volume of methylene chloride used
= 4.6 * 2 mL
= 9.2 mL
Now, let's calculate the total amount of caffeine extracted into the three portions of methylene chloride:
Total amount of caffeine extracted = Amount of caffeine extracted in first portion + Amount of caffeine extracted in second portion + Amount of caffeine extracted in third portion
= 9.2 mL + 9.2 mL + 9.2 mL
= 27.6 mL
Therefore, the total amount of caffeine that can be extracted into the three portions of methylene chloride is 27.6 mL.