Quantitative equilibrium calculations

Fundamentals
Problems
      Fraction of atrazine
           Help
           Answer
     Retardation factor
           Answer
     Raining out
           Answer
     Carpet
           Help
           Answer
     Sorption kinetics
           Help
           Answer
     Organic pollutants in water
           Answer
     Fish toxicity test
           Answer
     Ethylacetate
           Answer
     Tetrachlorobenzene
           Answer
     Hexachlorobenzene
           Answer
     Chlorobenzene
           Answer
     Toxicity test
           Answer
     Toxicity test - improving...
     3 phases problem
           Answer
     Sorption experiment
           Answer
     HCH
Excercises for an improved intuitive understanding
Questions for recapitulation
Good to know
Minesweeper-problems

Organic pollutants in water

For analyzing organic pollutants in water, the compounds may be pre-concentrated by extraction with an organic solvent. You have the job to determine the concentration of 1-naphthol in a contaminated groundwater by using gas chromatography.

You decide to extract 20 mL water samples with a convenient solvent:
ethylacetate at 25°C: Ki ethylacetate / water = 102.60 [L water /L ethylacetate ].

Now you wonder how much ethyl acetate you should use. Calculate the volume of ethylacetate that you need at minimum if you want to extract at least 99% of the total 1-naphthol from the water sample. Are you happy with this pre-concentration step? Somebody tells you that it would be much wiser to extract the sample twice with the goal to get each time 90% of the compound out of the water (which would also amount to an extraction efficiency of 99% in total), and then pool the two extracts.

 

Proceed