The distribution coefficient between ether & water for aspirin at room temperature is 3.5. What weight of aspirin would be extracted by a single extraction with 150 ml water from a solution of 10 gms of aspirin in 100 ml ether? Calculate the weight of aspirin which would be removed by three extractions with 50 ml portions of water.
x = wt aspirin in ether
10-x = st aspirin in H2O layer.
3.5 = (x/100)/(10-x/150
Solve for x and 10-x
7.5
To calculate the weight of aspirin extracted by a single extraction with 150 ml of water, we can use the distribution coefficient formula:
Weight of aspirin extracted = (Concentration of aspirin in water) / (Concentration of aspirin in ether)
Given:
- Distribution coefficient (K) = 3.5
- Initial weight of aspirin = 10 g
- Initial volume of ether = 100 ml
- Volume of water used in single extraction = 150 ml
First, we need to find the concentrations of aspirin in water and ether:
Concentration of aspirin in water = (Weight of aspirin in water) / (Volume of water)
Concentration of aspirin in ether = (Weight of aspirin in ether) / (Volume of ether)
The weight of aspirin in water is what we want to find. Let's denote it as "x".
x = (10 g) * (150 ml) / (1000 ml)
Note: We convert ml to grams by considering the density of water, which is approximately 1 g/ml.
x ≈ 1.5 g
Now, we can calculate the weight of aspirin extracted by a single extraction:
Weight of aspirin extracted = (Concentration of aspirin in water) / (Concentration of aspirin in ether)
Weight of aspirin extracted = (1.5 g) / (10 g / 100 ml)
Weight of aspirin extracted = 15 g / 10
Weight of aspirin extracted = 1.5 g
Therefore, a single extraction with 150 ml of water would extract approximately 1.5 grams of aspirin.
Now, let's calculate the weight of aspirin removed by three extractions with 50 ml portions of water.
For each extraction, the weight of aspirin removed will be the same, which is 1.5 grams (as calculated above).
Weight of aspirin removed by three extractions = (Weight of aspirin removed per extraction) * (Number of extractions)
Weight of aspirin removed by three extractions = 1.5 g * 3
Weight of aspirin removed by three extractions = 4.5 g
Therefore, three extractions with 50 ml portions of water would remove a total of 4.5 grams of aspirin.
To find the weight of aspirin extracted in a single extraction with 150 mL of water, we need to use the distribution coefficient between ether and water for aspirin. The distribution coefficient (Kd) is defined as the ratio of the concentration of a solute in one phase (in this case, water) to its concentration in another phase (ether) at equilibrium.
Given that the distribution coefficient between ether and water for aspirin is 3.5, it means that the concentration of aspirin in water is 3.5 times higher than in ether at equilibrium.
Now let's calculate the weight of aspirin extracted in a single extraction:
Step 1: Convert the volume of water used in the extraction from mL to L:
150 mL = 150 / 1000 L = 0.15 L
Step 2: Calculate the concentration of aspirin in the ether phase:
Concentration of aspirin in ether = 10 g / 0.1 L = 100 g/L
Step 3: Calculate the concentration of aspirin in the water phase at equilibrium:
Concentration of aspirin in water = Concentration of aspirin in ether / Kd
Concentration of aspirin in water = 100 g/L / 3.5 = 28.57 g/L
Step 4: Calculate the weight of aspirin extracted by a single extraction:
Weight of aspirin extracted = Concentration of aspirin in water × Volume of water
Weight of aspirin extracted = 28.57 g/L × 0.15 L = 4.28 g
Therefore, a single extraction with 150 mL of water would remove approximately 4.28 grams of aspirin.
Now let's calculate the weight of aspirin removed by three extractions with 50 mL portions of water:
Step 1: Convert the volume of each water portion used in the extractions from mL to L:
50 mL = 50 / 1000 L = 0.05 L
Step 2: Calculate the concentration of aspirin in the water phase at equilibrium for each extraction:
Concentration of aspirin in water = Concentration of aspirin in ether / Kd
Concentration of aspirin in water = 100 g/L / 3.5 = 28.57 g/L
Step 3: Calculate the weight of aspirin extracted in each extraction:
Weight of aspirin extracted = Concentration of aspirin in water × Volume of water
Weight of aspirin extracted = 28.57 g/L × 0.05 L = 1.43 g
Step 4: Calculate the total weight of aspirin removed by three extractions:
Total weight of aspirin removed = Weight of aspirin extracted × Number of extractions
Total weight of aspirin removed = 1.43 g × 3 = 4.29 g
Therefore, three extractions with 50 mL portions of water would remove approximately 4.29 grams of aspirin.