A standard analytical procedure for measuring the aqueous concentration (Cw) of

Question

A standard analytical procedure for measuring the aqueous concentration (Cw) of a highly hydrophobic compound with a low aqueous solubility (Cw SAT) is to first extract the hydrophobic compound from a large volume of water into a smaller volume of organic solvent such as octanol, and then analyze the concentration of the hydrophobic compound in the organic solvent (C oct).

What volume of octanol is required to extract 99.9% of pyrene present in 1L of a water sample?

Assume thermodynamic equilibrium and a constant tempertaure of 25 degrees Celcius.

Pyrene = C16H10, MW=202.26 grams/mole.

Explanation / Answer

solubility of pyrene in water=0.135 mg/L

so 1 L of water contains 0.135mg of Pyrene

99.9% 0f pyrene =0.135*0.999=0.1348 grams

Molarity of Pyrene in water=(0.1348/202.26)/1 =6.664*10^-4 mM

in octanol the molarity should be =6.664*10^-4 mM

6.664*10^-4*10^-3=(0.824*V/130.23) (0.824g/mL is the density of octanol)

V=0.105 L of octanol is required

Related Questions

Navigate

• Browse (All)
• Browse A
• Subjects

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.