Chapter 11, Problem 48P

The freezing point of 0.109 m aqueous formic acid is 0.210C. Formic acid, HCHO2, is partially dissociated according to the equation HCHO2(aq)H+(aq)+CHO2(aq) Calculate the percentage of HCHO2 molecules that are dissociated, assuming the equation for the freezing-point depression holds for the total concentration of molecules and ions in the solution.

A 0.109 mol/kg aqueous solution of formic acid, HCOOH, freezes at −0.210 °C. Calculate the percent dissociation of formic acid.

The freezing point of 0.10 M KHSO3 is -0.38C. Which of the following equations best represents what happens when KHSO3 dissolves in water? (a) KHSO3(s)KHSO3(aq) (b) KHSO3(s) K+(aq)+HSO3(aq) (c) KHSO3(s) K+(aq)+SO32(aq)+ H+(aq)

Use the following data to calculate the enthalpy of solution of sodium perchlorate, NaClO4: fH(s)=382.9kJ/mol and fH(aq,1m)=369.5kJ/mol

Freezing point depression is one means of determining the molar mass of a compound. The freezing point depression constant of benzene is 5.12 C/m. a. When a 0.503 g sample of the white crystalline dimer is dissolved in 10.0 g benzene, the freezing point of benzene is decreased by 0542 C. Verify that the molar mass of the dimer is 475 g/mol when determined by freezing point depression. Assume no dissociation of the dimer occurs. b. The correct molar mass of the dimer is 487 g/mol. Explain why the dissociation equilibrium causes the freezing point depression calculation to yield a lower molar mass for the dimer.

Temperature influences solubility. Does temperature have the same effect on all substances? Justify your answer. (Hint: Consider Le Chateliers principle.)

Benzene (C,H,) and toluene (C,H,CH;) form nearly ideal solutions. At 20°C the vapor pressure of benzene is 74.7 torr, and that of toluene is 22.3 torr. (a) Find the equilibrium par- vapor pressures above a 20°C solution of 100.0 g of benzene plus 100.0 g of toluene. (b) Find the mole fractions in the vapor phase that is in equilibrium with the solution of part (a). tial

The freezing point depression constant for benzene is 5.06°C/m and the freezing point of pure benzene is 5.51°C.  If a solution containing 2.241 g of a solid dissolved into 50.0 g of benzene, has a freezing point of 4.88°C, what is the molar mass of the solid?

When 89.1 mg of a certain molecular compound X are dissolved in 90. g of benzonitrile (C,H,CN), the freezing point of the solution is measured to be -13.2 °C. Calculate the molar mass of X. If you need any additional information on benzonitrile, use only what you find in the ALEKS Data resource. Also, be sure your answer has a unit symbol, and is rounded to the correct number of significant digits. x10