Compound Y has a distribution coefficient of 4.0 when extracted from water with chloroform, with Y being more soluble in chloroform. How many 10.0 mL chloroform extractions would be required to extract at least 95% of Y from a 50.0 mL aqueous solution of water?

Respuesta :

For the extraction of at least 95% of Y in water, 3 extractions are to be performed.

Distribution coefficient can be defined as the ratio of the concentration of solute in an organic solvent to water.

Distribution coefficient = [tex]\rm \dfrac{concentration\;in\;solvent}{concentration\;in\;water}[/tex]

  • For the first extraction, the concentration in organic solvent = X per 10 ml

Concentration in water = 100-X per 50 ml

Distribution coefficient = [tex]\rm \dfrac{\frac{X}{10} }{\frac{100-X}{50} }[/tex]

4 = [tex]\rm \dfrac{\frac{X}{10} }{\frac{100-X}{50} }[/tex]

4 = [tex]\rm \dfrac{50X}{1000-X}[/tex]

4000 - 4X = 50X

X = 74.1 %

Thus, after the first extraction, the amount of Y extracted is 74.1%.

We have to extract at least 95% of Y. Thus, the second extraction is performed.

  • Remaining y = 100 - 74.1

Remaining y = 25.9%

The concentration in organic solvent = X per 10 ml

Concentration in water = 25.9 -X

Distribution coefficient = [tex]\rm \dfrac{\frac{X}{10} }{\frac{25.9-X}{50} }[/tex]

4 = [tex]\rm \dfrac{\frac{X}{10} }{\frac{25.9-X}{50} }[/tex]

4 = [tex]\rm \dfrac{50X}{259-X}[/tex]

1036 - 4X = 50X

X = 19.2%

Thus, after the second extraction the amount of Y extarcted = first extraction + second extraction

The amount of Y extracted = 74.1 + 19.2 %

The amount of Y extracted = 93.3%

  • To reach at least 95% extraction, the third extraction has to be performed.

The remaining Y for third extraction = 100 - 93.3

The remaining Y for the third extraction = 6.7%

Concentration in water = 100 - 6.7

Distribution coefficient = [tex]\rm \dfrac{\frac{X}{10} }{\frac{6.7-X}{50} }[/tex]

4 = [tex]\rm \dfrac{\frac{X}{10} }{\frac{6.7-X}{50} }[/tex]

4 = [tex]\rm \dfrac{50X}{67-X}[/tex]

268 - 4X = 50X

X = 5.0%

The total extraction after third extraction = 93.3 + 5%

The total extraction after third extraction = 98.3%.

Thus for the extraction of at least 95% of Y in water, 3 extractions are to be performed.

For more information about the distribution coefficient, refer to the link:

https://brainly.com/question/13599982