The normal boiling point of methanol is 64.7 degree C. A solution containing a n

Question

The normal boiling point of methanol is 64.7 degree C. A solution containing a non-volatile solute dissolved in methanol has a vapor pressure of 710.0 Torr at 64.7 degree C. What is the mole fraction of methanol in this solution? Calculate the freezing point depression = (K_f^H_2O = 1.86 degree C/m) and osmotic pressure (R = 8.314 J/mol K) at 25 degree C of an aqueous solution containing 1.0 g/L of a protein (molar mass = 9.0 times 10^4 g/mol) if the density of the solution is 1.0 g/mL. Considering your answers to problem 2, which colligative property, freezing point depression or osmotic pressure, would be better to measure the molar mass of large molecules? Explain your rational. A soft drink is made by dissolving CO_2 gas at 3.60 atm in a flavored solution and sealing the solution in aluminum cans at 20 degree C. What amount of CO_2 is contained in a 360.-mL can of the drink? A 0.124 m CCl_3COOH (aq) solution has a freezing point of -0.423 degree C. What is the percent deprotonation of the acid?

Explanation / Answer

(1) At normal boiling point the vapour pressure of methanol = 760 torr

The vapor pressure of solution = 710 torr

According to Raoult's law, for the solutions having non volatile solute,

relative lowering of vapor pressure = mole fraction of solute

(or)

(p0 - p) / p0 = mole fraction of solute

(760 - 710) / 760 = mole fraction of solute

mole fraction of solute = 0.06579

For a binary solution,

mole fraction of solute + mole fraction of solvent = 1

0.06579 + mole fraction of solvent = 1

Therefore, mole fraction of solvent = 0.9342

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