Solute S has a partition coefficient of 4.3 between water (phase 1) and hexane (phase 2).
(a) Calculate the concentration of S in hexane if [Swater] is 0.030 M
(b) If the volume of water is 71.0 mL and the volume of hexane is 16.0 mL, find the quotient (mol S in hexane/mol S in water).
It isn't clear to me how your partition coefficient is defined. IF it is
Kphase 1/phase 2 = 4.3 it is done as follows
4.3 = (in H2O)/(in hexane) = (0.03/x and solve for x.
However, I strongly suspect it is defined as
Kphase 2/phase 1. You can move the numbers around accordingly.
To solve this problem, we need to use the partition coefficient (also known as distribution coefficient) which is defined as the ratio of the concentration of a solute in one phase to its concentration in another phase at equilibrium.
(a) To calculate the concentration of S in hexane, given [Swater] is 0.030 M and the partition coefficient is 4.3, we can use the formula:
[Shexane] = Kp * [Swater]
where Kp is the partition coefficient.
Substituting the given values:
[Shexane] = 4.3 * 0.030 M
[Shexane] = 0.129 M
Therefore, the concentration of S in hexane is 0.129 M.
(b) To find the quotient (mol S in hexane/mol S in water), we need to calculate the number of moles of S in both phases.
The number of moles can be calculated using the formula:
moles = concentration * volume
For water:
moles of S in water = [Swater] * volume of water
moles of S in water = 0.030 M * 0.071 L (since 71 mL = 0.071 L)
moles of S in water = 0.00213 mol
For hexane:
moles of S in hexane = [Shexane] * volume of hexane
moles of S in hexane = 0.129 M * 0.016 L (since 16 mL = 0.016 L)
moles of S in hexane = 0.002064 mol
Now, we can calculate the quotient:
quotient (mol S in hexane/mol S in water) = moles of S in hexane / moles of S in water
quotient = 0.002064 mol / 0.00213 mol
quotient ≈ 0.968
Therefore, the quotient (mol S in hexane/mol S in water) is approximately 0.968.