1) Calculate the partition coefficient of caffeine in water/methylene
chloride from the following data: 10.3 g/100 mL for methylene
chloride and 2.04 g/100 mL for water.
2. A student is sure that
0.500 grams of caffeine is dissolved in 125 mL of water. The student extracts the caffeine using a single extraction of 21 mL of methylene chloride. How much caffeine is in the methylene chloride? How much remains in the water?
3. Using the same data from #1, a student follows the procedure and extracts the caffeine using 3 extractions of 7 mL of methylene chloride. How much caffeine is in the combined 21 mL of methylene chloride? How much remained in the water?
So far I got kp=5.05 and I think b would be 0.49? Please help with steps, I am so confused!
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1) To calculate the partition coefficient of caffeine in water/methylene chloride, we can divide the solubility of caffeine in methylene chloride by its solubility in water.
Partition coefficient (P) = Solubility in Methylene Chloride / Solubility in Water
For methylene chloride: Solubility = 10.3 g/100 mL
For water: Solubility = 2.04 g/100 mL
Plugging in the values:
P = 10.3 g/100 mL / 2.04 g/100 mL
Simplifying:
P = 10.3 / 2.04
Therefore, the partition coefficient of caffeine in water/methylene chloride is approximately 5.05.
2) The student extracted caffeine using a single extraction of 21 mL of methylene chloride. To calculate how much caffeine is in the methylene chloride and how much remains in the water, we need to determine the partition coefficient and use mass balance.
Given data:
Mass of caffeine = 0.500 grams
Volume of water = 125 mL
Volume of methylene chloride used for extraction = 21 mL
First, calculate the mass of caffeine in the methylene chloride:
Mass of caffeine in methylene chloride = Mass of caffeine * (Volume of methylene chloride / Volume of water + Volume of methylene chloride)
= 0.500 grams * (21 mL / (125 mL + 21 mL))
= 0.500 grams * (21 mL / 146 mL)
= 0.0721 grams
Therefore, there is approximately 0.0721 grams of caffeine in the methylene chloride.
Now, calculate the remaining amount of caffeine in the water:
Mass of caffeine in water = Mass of caffeine - Mass of caffeine in methylene chloride
= 0.500 grams - 0.0721 grams
= 0.4279 grams
Therefore, there is approximately 0.4279 grams of caffeine remaining in the water.
3) Assuming the same partition coefficient as in question 1 and using the same set of data, if the student follows the procedure and extracts caffeine using 3 extractions of 7 mL of methylene chloride, we can calculate the amount of caffeine in the combined 21 mL of methylene chloride and the remaining amount in the water.
Given data:
Mass of caffeine = 0.500 grams
Volume of water = 125 mL
Volume of methylene chloride used for each extraction = 7 mL
Number of extractions = 3
First, calculate the mass of caffeine in the combined 21 mL of methylene chloride:
Mass of caffeine in methylene chloride = Mass of caffeine * (Volume of methylene chloride / Volume of water + Volume of methylene chloride) * Number of extractions
= 0.500 grams * (7 mL / (125 mL + 7 mL)) * 3
= 0.500 grams * (7 mL / 132 mL) * 3
= 0.1061 grams
Therefore, there is approximately 0.1061 grams of caffeine in the combined 21 mL of methylene chloride.
Now, calculate the remaining amount of caffeine in the water:
Mass of caffeine in water = Mass of caffeine - Mass of caffeine in methylene chloride
= 0.500 grams - 0.1061 grams
= 0.3939 grams
Therefore, there is approximately 0.3939 grams of caffeine remaining in the water.
To calculate the partition coefficient of caffeine in water/methylene chloride, we need to divide the solubility of caffeine in methylene chloride by the solubility of caffeine in water.
1) Partition coefficient (P) = Solubility in Methylene Chloride / Solubility in Water
Given:
Solubility of caffeine in methylene chloride = 10.3 g/100 mL
Solubility of caffeine in water = 2.04 g/100 mL
P = 10.3 g/100 mL / 2.04 g/100 mL
P ≈ 5.05
Therefore, the partition coefficient of caffeine in water/methylene chloride is approximately 5.05.
2) To determine how much caffeine is in the methylene chloride and how much remains in the water after a single extraction:
Given:
Initial amount of caffeine = 0.500 grams
Volume of water used for extraction = 125 mL
Volume of methylene chloride used for extraction = 21 mL
Using the partition coefficient from the previous calculation, we can determine the amount of caffeine extracted into the methylene chloride and the amount remaining in the water.
Amount of caffeine in the methylene chloride (C_MC):
C_MC = (Volume of methylene chloride / Total volume) x Initial amount of caffeine
C_MC = (21 mL / (21 mL + 125 mL)) x 0.500 grams
C_MC ≈ 0.065 grams
Therefore, there is approximately 0.065 grams of caffeine in the methylene chloride after a single extraction.
Amount of caffeine remaining in the water (C_water):
C_water = Initial amount of caffeine - C_MC
C_water ≈ 0.500 grams - 0.065 grams
C_water ≈ 0.435 grams
Therefore, approximately 0.435 grams of caffeine remains in the water after a single extraction.
3) To determine how much caffeine is in the combined 21 mL of methylene chloride and how much remains in the water after three extractions of 7 mL of methylene chloride each:
Using the same partition coefficient from the previous calculation:
Amount of caffeine extracted in each 7 mL extraction (C_MC_single):
C_MC_single = (7 mL / (7 mL + 125 mL)) x 0.500 grams
C_MC_single ≈ 0.021 grams
To determine the total amount of caffeine in the combined 21 mL of methylene chloride, we multiply the amount extracted in each single extraction by the number of extractions (3 in this case):
Total amount of caffeine in the combined 21 mL of methylene chloride (C_MC_combined):
C_MC_combined = C_MC_single x Number of extractions
C_MC_combined = 0.021 grams x 3
C_MC_combined ≈ 0.063 grams
Therefore, there is approximately 0.063 grams of caffeine in the combined 21 mL of methylene chloride after three extractions.
To determine the amount of caffeine remaining in the water after three extractions:
Amount of caffeine remaining in the water (C_water_remaining) = Initial amount of caffeine - C_MC_combined
C_water_remaining = 0.500 grams - 0.063 grams
C_water_remaining ≈ 0.437 grams
Therefore, approximately 0.437 grams of caffeine remains in the water after three extractions.