A 1.0 gram sample of aspirin will dissolve in 300 mL of water and in 17 mL of chloroform at 25 deg C.
a. What is the solubility of aspirin in each solvent expressed in g/mL? (show your calculations)
I don't know where to start, does the molecular weight come into play (180.157g/mol - aspirin)
b. What is the partition coefficient of aspirin between chloroform and water?
You want the solubility expressed as g/mL. So
1.0g/300 mL = 0.333 g/100 mL. Right?
And 1.0 g/17 mL is
1/17 = about 0.06 g/mL or approx 6 g/100 mL.
Then Ko/a = approx 6/0.333 = about ? in which Ko/a is the partition coefficient of organic/aqueous.
a. To calculate the solubility of aspirin in each solvent, we need to find the concentration of the solute (aspirin) in each solvent.
1. Solubility in water:
We know that a 1.0 gram sample of aspirin dissolves in 300 mL of water. To find the concentration in g/mL, we divide the mass of aspirin by the volume of water.
Concentration of aspirin in water = mass of aspirin / volume of water
Concentration = 1.0 g / 300 mL
However, we need to convert mL to L to make the units consistent:
Concentration = 1.0 g / 0.3 L
Concentration = 3.33 g/L
Therefore, the solubility of aspirin in water is 3.33 g/mL.
2. Solubility in chloroform:
Similarly, we know that the 1.0 gram sample of aspirin dissolves in 17 mL of chloroform. Again, we divide the mass of aspirin by the volume of chloroform to find the concentration.
Concentration of aspirin in chloroform = mass of aspirin / volume of chloroform
Concentration = 1.0 g / 17 mL
Converting mL to L:
Concentration = 1.0 g / 0.017 L
Concentration = 58.82 g/L
Therefore, the solubility of aspirin in chloroform is 58.82 g/mL.
b. The partition coefficient of a solute between two immiscible solvents (such as chloroform and water) is defined as the ratio of solute concentration in one solvent to its concentration in the other solvent at equilibrium.
Partition coefficient = Concentration of aspirin in chloroform / Concentration of aspirin in water
Using the concentrations we calculated earlier:
Partition coefficient = 58.82 g/L / 3.33 g/L
Partition coefficient = 17.66
Therefore, the partition coefficient of aspirin between chloroform and water is 17.66.
a. To find the solubility of aspirin in each solvent expressed in g/mL, we can use the formula:
Solubility (g/mL) = Mass of solute (g) / Volume of solvent (mL)
For water:
Volume of water = 300 mL
Mass of aspirin = 1.0 g
Solubility in water = 1.0 g / 300 mL = 0.0033 g/mL
For chloroform:
Volume of chloroform = 17 mL
Mass of aspirin = 1.0 g
Solubility in chloroform = 1.0 g / 17 mL ≈ 0.059 g/mL
b. The partition coefficient (Kp) of a compound between two immiscible solvents is defined as the ratio of its concentrations in the two solvents at equilibrium. In this case, the partition coefficient of aspirin between chloroform and water can be calculated using the formula:
Kp = Concentration of aspirin in chloroform / Concentration of aspirin in water
To find the concentrations, we can divide the solubilities in each solvent by their respective molecular weights:
Concentration of aspirin in water = Solubility in water / Molecular weight of aspirin
= 0.0033 g/mL / 180.157 g/mol ≈ 0.000018 g/mL
Concentration of aspirin in chloroform = Solubility in chloroform / Molecular weight of aspirin
= 0.059 g/mL / 180.157 g/mol ≈ 0.000328 g/mL
Now we can calculate the partition coefficient:
Kp = 0.000328 g/mL / 0.000018 g/mL ≈ 18.2