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the equilibrium vapor pressure of water at 30 degrees C is 31.6 torr. when 22.4

ID: 478695 • Letter: T

Question

the equilibrium vapor pressure of water at 30 degrees C is 31.6 torr. when 22.4 g of a nonvolatile nonelectrolyte solute in 50 g of water the vapor pressure of the solution is 2.50 torr lower than that of pure water at 30 degrees C what is the molecular weight of the solute? the equilibrium vapor pressure of water at 30 degrees C is 31.6 torr. when 22.4 g of a nonvolatile nonelectrolyte solute in 50 g of water the vapor pressure of the solution is 2.50 torr lower than that of pure water at 30 degrees C what is the molecular weight of the solute? the equilibrium vapor pressure of water at 30 degrees C is 31.6 torr. when 22.4 g of a nonvolatile nonelectrolyte solute in 50 g of water the vapor pressure of the solution is 2.50 torr lower than that of pure water at 30 degrees C what is the molecular weight of the solute?

Explanation / Answer

P° = 31.6 torr pure

m = 22.4 g of x

m = 50 g of water

dP°mix = 2.5

apply:

dP = xsolute* P°solvent pure

2.5 = xsolute*31.6

xsolute = 2.5/31.6 = 0.079113

so...

x solute= mol of solut / total mol

assume...

mol of water = mass/MW = 50/18 = 2.77 mol of water

0.079113 = x / (x+2.77)

where x is mol of solute

solve for x

0.079113x + 2.77*0.079113 = x

(1-0.079113)x = 2.77*0.079113

x = (2.77*0.079113) / (1-0.079113)

x = mol of solut

MW = mass/mol = 22.4/0.23796 = 94.133 g/mol