Question

The experiment above is repeated, but instead of extracting once with 6 mL the extraction is done three times with 2 mL of dichloromethane each time. How much caffeine will be in each dichloromethane extract?

Answer 1

Complete Question

A student is extracting caffeine from water with dichloromethane. The K value is 4.6. If the student starts with a total of 40 mg of caffeine in 2 mL of water and extracts once with 6 mL of dichloromethane

The experiment above is repeated, but instead of extracting once with 6 mL the extraction is done three times with 2 mL of dichloromethane each time. How much caffeine will be in each dichloromethane extract?

Answer:

The mass of  caffeine extracted is  $P = 39.8 \ mg$

Explanation:

From the question above  we are told that

    The  K value is  $K = 4.6$

     The  mass of the caffeine is  $m = 40 mg$

      The  volume of water is  $V = 2 mL$

      The volume  of caffeine is  $v_c = 2 mL$

     The number of times the extraction was done is  n =  3

Generally the mass of  caffeine that will be  extracted is  

           $P = m * [\frac{V}{K * v_c + V} ]^3$

substituting values  

           $P = 40 * [\frac{2}{4.6 * 2 + 2} ]^3$

           $P = 39.8 \ mg$