CHM 1046                           TEST  4         Name _______________________
August 2, 1996                                 (please print)                  
                                                  Soc.Sec.Num. ________________

     This exam consists of four pages.  Make sure you
have one of each.  Print your name at the top of each
page now.  Show your work on calculations, and give
answers to the correct number of significant figures. 
You may use atomic weight values rounded to the
nearest 0.1 amu.

     A periodic chart and other information you will
need are given on a fifth page.  You may tear this
page off and use it for scratch paper.

     If anything confuses you or is not clear, raise
your hand and ask!

Points

(20)1.The following reaction describes the preparation of water gas from
     coal.  Water gas is used as a fuel.  Calculate delta Go and Kp for
     this reaction at both 500 oC and 1000 oC.  Which is the more favored
     temperature for producing the water gas?

           C(s)  +   H2O(g)  þ    CO(g)   +   H2(g)



























(10)2.Calculate delta G for the following reaction at 250oC if [H2] is 10
     atmospheres and [CH4] is 20 atmospheres:

           C(s)    +  2 H2(g)   --->   CH4(g)


















(6)3.Put a check by the following changes that lead to a decrease in
     entropy of the system:

     ____  oxidizing carbon monoxide to carbon dioxide

     ____  sublimation of carbon dioxide from solid to gas

     ____  freezing of water


(4)4.Put a check by the following conditions in which a reaction is
     considered spontaneous.

     ____  Keq < 1

     ____  delta Ho < O, delta So > O

     ____  delta Ho > O, delta So < O

     ____  delta Go < O


(4)5.Dissolving ammonium chloride in water causes the temperature of the
     system to drop.  For this process: (check the correct answer)

     ___   (a)  enthalpy decreases and entropy decreases

     ___   (b)  enthalpy increases and entropy decreases

     ___   (c)  enthalpy decreases and entropy increases

     ___   (d)  enthalpy increases and entropy increases

(4)6.For a reaction to be spontaneous at high temperatures and non-
     spontaneous at low temperatures, it must have: (check the correct
     answer)

     ___   (a)  negative delta H and negative delta S

     ___   (b)  negative delta H and positive delta S

     ___   (c)  positive delta H and negative delta S

     ___   (d)  positive delta H and positive delta S


(12)7.For the following redox reaction, write and balance both half cell
     reactions in basic solution, then give the overall balanced
     equation in basic solution.

     CrO42-   +   Sn(OH)2(s)   þ   Cr(OH)3(s)   +   Sn(OH)4(s)















8.   A voltaic cell using the following reaction has a measured emf
     under standard conditions of 1.03 V:

     PdCl42-(aq) + Cd(s) --->  Pd(s)  +  4 Cl-(aq)  +  Cd2+(aq)

     Eo for the reduction of Cd2+ is -0.403 V.

(5)  (a)   What is Eo for the reduction of PdCl42-?






(5)  (b)   What is delta Go for the reaction as written?





(2)  (c)   Which metal is the anode? _____

(2)  (d)   Which metal is the cathode? _____



(8)9.You want to plate a coating of copper on to a metal dish to improve
     its appearance.  You figure it will take 25 g of copper to produce
     a thick enough coat.  Your electroplating equipment can generate
     10.0 amperes of electric current.  How long must you carry out the
     electroplating in order to deposit 25 g of copper from Cu(NO3)2
     solution?















(8)10.Give the molecular formula for the following:

     (a) butane      (b) octane      (c) pentane     (d) propane







(10)11.There are five structural isomers of C6H14.  Draw a condensed
     structural formula for each, and name each isomer.