Gasoline is a mixture of primarily aliphatic (>50%) and aromatic(approx.30%) hydrocarbons with an average molar mass of about105g/mol and a density of 0.75g/cm3 . For a gasoline spill underneatha gas station, among the compounds of concern are benzene and3,4-dimethylamiline (DMA). The spilled gasoline contains 2 volumepercent benezene and 10mg/L DMA.Gasoline water partitioncoefficients of 300Lw/Lgasoline for benzene and30Lw/Lgasoline forDMA (at pH 8 where DMA is present primarily as a neutral species)have been measured.

a) Using the gasoline-water partition coefficients, calculatethe activity coefficients of benezene and DMA in the gasolinemixture of interest. Which of the two values do you trustmore?
b) What benzene and DMA concentration would you expect ingroundwater that is in equilibrium with a large pool of the spilledgasoline at 25 degrees C (ie., assume that the gasoline compositionis not altered significantly by the dissolution of the componentsin the aqueous phase)

All necessary data in appendix C of Environmental OrganicChemistry.
Hint: to estimate the mole fraction of a component from itsvolume fraction, assume a binary mixture of the component with asolvent that has the average molar volume of the gasolinemixture.
(From Environmental organic chemistry, 2nd ed,2003,Schwarzenbach,Gschwend and Imboden)

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