Question

Solute S has a partition coefficient of 4.6 between water (phase 1) and hexane (phase 2). Calculate the concentration of solute S in hexane if [S]water=0.020M

1.[S]hexane=____________M not 0.0043M

2.If the volume of water is 67.0 mL and the volume of hexane is 20.0 mL, find the ratio of the moles of solute S in hexane to the moles of solute S in water.

[S]hexane/[S]water=__________________ not 0.0648

Answer 1

Answer:

1. [S]hexane = 0.092 M

2. Ratio = 0.006164

Explanation:

1.

Formula for Partition Coefficient(K) is as follows,

K – = Molarity in organic phase Molarity in aqueous phase

Hexane is the organic layer and water is the aqueous layer.

So, molarity in aqueous phase = [S]water = 0.020 M

molarity in organic phase = [S]hexane = we need to find out.

K = 4.6

Now, put these values in the formula for K,

R = Molarity in organic phase Molarity in aqueous phase 4.6 = Molarcity in organic phase 0.020 M Malarity in organic phase = 4.68 0.020M Molarcity in organic phase = 0.092M ) [s] henane = 0.092m

2.

Now we know the Molarity of solute S in water and hexane.

Now we need to calculate the moles of Solute in water and hexane using following equation,

Number of moles = Molarity × Volume

Number of moles of S in hexane:

now put these values in the equation for number of moles,

ZL [shenane = 0.092 M = 0.092 may Volume of herane = 67.0 mL = 0.067L

enane = 0.092 No. of moles of sin henane = 0.092 mal x 0.067X No. of moles of S in hexane = 0.006164 mal

Number of moles of S in water:

now, put these values in the equation for number of moles,

[s] water = 0.020M = 0.020 mol/ volume of water = 20mL = 0.020L

No. of males of sin water = 0.020 mol/xx 0.020x No. of moles of s in water = 1 onal

So, ratio of moles of solute S in hexane to water is,

No. of males of sin henone No. of males of sin water - 0.006164 royal = 10.006164 1 rool

Ratio is, 0.006164