Suppose that you must go into court and testify as to the level of X in the river water. Your lawyer is concerned that your analytical results are lower than they should be because you cannot extract with benzene (distribution Ratio K=4) all of X from your samples. Assume the concentration of X in the 1.00 L river water sample is 1.06 x 10-4 M.
a. How many extracts would be required to remove all but 1000 molecules of X from the sample with repeated 10.00 mL portions of extract?
b. How many extractions are required for a 99.99% chance of extraction of the last molecule remaining (0.01% chance of a single molecule left behind)

Respuesta :

Answer:

The appropriate solution is:

(a) n ≈ 900

(b) n ≈ 1165

Explanation:

According to the question,

(a)

The final number of molecules throughout water will be:

= [tex](\frac{1000}{1000}\times 4\times 10 )^n[/tex]

where, n = number of extractions

Now,

The initial number of molecules will be:

= [tex]1.06\times 10^{-4}\times 6.023\times 10^{23}[/tex]

= [tex]6.387\times 10^{19}[/tex]

Final number of molecule,

⇒ [tex]1.566\times 10^{-16}=(\frac{1000}{1040} )^n[/tex]

                       [tex]n \approx 900[/tex]

(b)

Final molecules of X = left (0.01%)

hence,

⇒ [tex]initial = 6.384\times 10^{19}[/tex]

   [tex]\frac{1}{6.384\times 10^{19}} =(\frac{1000}{1040} )^2[/tex]

                 [tex]n \approx 1165[/tex]