Question

The distribution coefficient between hexanes and water for solute B is 7.5. What weight of B would be removed from a solution of 5.00 g of B in 50 mL of water by a single extraction with 50 mL of hexanes?

Answer 1

4.41g

Explanation

Distribution coefficient, K_d = (Concentration of solute)_organic/(Concentration of solute)_water

_{If concentration unit is g/L}

7.5 =( (mass of B in Hexane/50ml) × 1000ml )/ ((mass of B in water/50ml)×1000ml )

cancelling 1000ml/50ml

mass of B in Hexane /mass of B in water = 7.5

if mass of B in Hexane = x

mass of B in water = 5 -x

x/(5 - x) = 7.5

x =7.5 (5 -x)

x = 37.5 -7.5x

8.5x = 37.5

x = 4.41

5- x = 5 - 4.41 = 0.59

Therefore

4.41g of B would be removed from single extraction