A stoppered flask at 25 C contains 250 mL water, 200 mL octanol, and 50 mL of air. An unknown mass of o-xylene is added to the flask and allowed to partition among the phases. After equilibrium has been established, 5.0 mg of o-xylene are measured in the water. What is the total mass (g) of o-xylene present in the flask?
Do you have the partition coefficient.
Korganic/aqueous = ??
To find the total mass of o-xylene present in the flask, we can first calculate the mass of o-xylene in the water phase.
Given:
- A total volume of the mixture = 250 mL + 200 mL + 50 mL = 500 mL
To convert milliliters (mL) to grams (g), we need to know the density of water and octanol. Assume the density of water is 1 g/mL, and the density of octanol is also 1 g/mL.
Mass of o-xylene in water phase = 5.0 mg
1. Convert the mass of o-xylene in water phase to grams:
Mass of o-xylene in water phase = 5.0 mg * (1 g/1000 mg) = 0.005 g
Since the volume of the water phase is 250 mL:
Concentration of o-xylene in the water phase = mass/volume = 0.005 g / 250 mL
2. Calculate the mass of o-xylene in the entire mixture:
Concentration of o-xylene in the entire mixture = concentration in water phase
To find the mass of o-xylene in the entire mixture, we can use the equation:
Mass of o-xylene in the entire mixture = concentration * total volume
Mass of o-xylene in the entire mixture = (0.005 g / 250 mL) * 500 mL
Therefore, the total mass of o-xylene present in the flask is 0.01 g.
To determine the total mass of o-xylene present in the flask, we need to consider the equilibrium partitioning among the phases (water, octanol, and air).
First, let's convert the given measurements into common units.
The volume of water is given as 250 mL, the volume of octanol as 200 mL, and the volume of air as 50 mL.
Next, let's convert these volumes to grams using their respective densities at 25°C. The density of water is approximately 1 g/mL, octanol is 0.83 g/mL, and air can be ignored due to its negligible density.
So, the mass of water is 250 g, and the mass of octanol is 200 g.
Now, we can calculate the concentration (C) of o-xylene in the water phase using the measured amount of o-xylene (5.0 mg) and the mass of water.
C = (mass of o-xylene in water) / (mass of water)
C = 5.0 mg / 250 g
C = 0.02 mg/g
Since the o-xylene is in equilibrium and partitions between the phases, we assume the concentration of o-xylene in octanol is the same as in water.
Therefore, the total mass of o-xylene in the flask can be calculated as follows:
Total mass of o-xylene = (concentration of o-xylene in water) * (mass of water + mass of octanol)
Total mass of o-xylene = 0.02 mg/g * (250 g + 200 g)
Total mass of o-xylene = 0.02 mg/g * 450 g
Total mass of o-xylene = 9 mg
Finally, we can convert the mass to grams:
Total mass of o-xylene = 9 mg * (1 g / 1000 mg)
Total mass of o-xylene = 0.009 g
Therefore, the total mass of o-xylene present in the flask is approximately 0.009 grams.