CHEM 4010                                                                 Name_________________

Dr. Perona                                                                  May 27, 2005

 

Final Exam

Do problems 1 through 9 and either 10 or 11.  You must show all of your work to receive full credit.

 

1. (20) Lead and bismuth form ideal solutions.  Predict the mole fraction solubility of lead in bismuth at 280oC, given that for lead the melting point and enthalpy of fusion are 327oC and 5.2 kJ mol-1, respectively.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

2. (25) In an experiment, 17.1 g of a nonvolatile solute having a molar mass of 342 g/mol, Is dissolved in 250. g of water (molar mass = 18.02 g/mol, density = 1.00 g/mL). The cryoscopic (freezing point depression) constant of water is 1.86 K/(mol/kg) and its normal freezing point is 273.15 K. 

 

a)      What is the freezing point of the solution?

 

b)      What is the osmotic pressure of the solution at 298 K?

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

3. (10)  Heptane and hexane form nearly ideal solutions. The temperature versus composition diagram at a constant pressure of 1 atm is shown below.  In the Table, indicate the  phase or phases (gas, solid, liquid) present in each of the regions A, B and C in the diagram.

 

 

Region

Number and kind of phase(s)

A

 

B

 

C

 

 

 

4.  (10) A mixture of heptane and hexane is prepared with an overall mole fraction of heptane, Xheptane = 0.5.  Use the phase diagram in problem 3 to answer the questions below.

        

a)      At what temperature will this mixture boil?

 

 

         b)  What is the composition of the vapor when boiling first occurs?

 

 

 

 

 

 

 

 

5.      (25) A sample of aluminum (atomic mass = 26.981 u,  = 24.35 J-1 K-1 mol-1) of mass 1.75 kg, is cooled from 25.0 oC to –5.0 oC at constant pressure, by placing it in a freezer whose temperature is maintained at a constant value of -5.0 oC.  Calculate:


(a) the entropy change of the sample.   

(b) the entropy change for the surroundings (the inside of the freezer).

 

(c) what is the total entropy change of the sample and its surroundings?  Is the value consistent with the predictions of the Second Law of thermodynamics?  Please explain.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

6.      (23) A 0.200 mole sample of ideal gas (), initially at a temperature of 300 K, undergoes an adiabatic expansion in which it performs 100 J of work.

 

a) Calculate the final temperature of the gas.

b)   Calculate DU and DH for the gas.

 

 



 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

7.      (20) Given the equation:

 

      show,  in detail, that for an ideal gas

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

8.   (23) A 0.500 mole sample of an ideal gas initially occupies a volume of 50.0 L at 22 oC. It expands isothermally and reversibly to a final volume of 150.0 L.  For this process calculate:

a) q, the heat absorbed by the gas.

 

      b)   w, the work done on the gas

c)   DU,  DH, DG and DS Hint: for ideal gas

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

9.      (24) Copper sulfate monohydrate decomposes according to the reaction:


CuSO4.H2O(s) ⇆ CuSO4(s) + H2O(g)


Given the data below:

           

Compound

DfH, kJ mol-1, at 298 K and 1 bar

DfG, kJ mol-1, at 298 K and 1 bar

CuSO4(s)

-771.36

-661.8

CuSO4.H2O(s)

-1085.83

-918.11

H2O(g)

-241.818

-228.572

 

a)      What is the equilibrium partial pressure of H2O vapor over a mixture of CuSO4(s) and CuSO4.H2O(s) at 298 K?

 

 

 

 

 

 

 

 

 

 

 

b)      What is the equilibrium partial pressure of H2O vapor over a mixture of CuSO4(s) and CuSO4.H2O(s) at 373 K?

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

10.     (20) The partial pressure of CO2 gas in a bottle of soda pop is 4 atm.  What is the molal concentration of dissolved CO2 in the soda pop at 25oC?  Use the Henry’s law constant for CO2 in water which is 1.67 x 108 Pa at 25 oC, and assume that the soda is a solution of CO2 in pure water.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

11. (20) In a pressurized-water nuclear reactor, liquid water under a pressure of 148 atm is used to transfer heat energy out of the core.  What is the boiling point of water at this pressure? The normal boiling point of water is 273.15 K and its enthalpy of vaporization is 40.66 kJ mol-1.