12.)Pure water vapor pressure reaches 149.4 Torr at 60 C. Calculate the vapor pr

Question

12.)Pure water vapor pressure reaches 149.4 Torr at 60 C. Calculate the vapor pressure of a solution made of 82 g of an involatile organic compound (molar mass 82g/mol) and 2000 g water, assuming the solution obeys Raoult's Law (a.) 148 (b.) 138 (c.) 128 (d.) 118 13.)Calculate the osmotic pressure (atm) of the solution formed in the last question at 60 C. The density of water is 1 g/cm or 10'g/L and assuming that adding the involatile organic compound does not affect the solution volume R=0.062061 atm mol-1 K-1 (a.) 0.17 atm (b.) 1.72 atm (c.) 13.7 atm (d.) 27.2 atm

Explanation / Answer

moles of involatile compound= mass/molar mass= 82/82= 1 moles

moles of water in 1000gm=1000/18= 55.56 moles

mole fraction of water = moles of water/total moles= 55.56/(55.56+1)=0.9823

vapor pressure of water in solution = mole fraction of water* pure component vapor pressure =149.4*0.9823 =147 Torr (close answer is 148 torr).

2. Osmotic presssure = CRT, C= concentration of solution in gmole/L, R= 0.0821 L.atm/mole.K, T= 60deg.c= 60+273= 333K, moles of solute= 1 , volume of solution = 2000 g/1gm/cc= 2000Cc= 2L

concentration of solution = 1/2=0.5moles/L

Osmotic presssure = 0.5*0.0821*333 atm =13.7 atm

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