1.  Select the polyprotic acid from among the following.


     A.  HCN

     B.  (NH4)2SO4

     C.  H2C2O4

     D.  Ca(OH)2


 2.  The curve shown in the diagram below represents the titration of




     A.  a strong acid with a weak base.

     B.  a strong acid with a strong base.

     C.  a weak acid with a weak base.

     D.  a weak acid with a strong base.


 3.  In region A in the diagram shown in the previous question, the

     solution being titrated is


     A.  neutral.

     B.  an indicator.

     C.  basic.

     D.  a buffer.


 4.  When dissolved in water, which pair of compounds would form a buffer?


     A.  KOH and HNO3

     B.  KNO2 and HNO2

     C.  KNO2 and NaNO2

     D.  KNO3 and HNO3


 5.  Which one of the following statements is true?


     A.  A buffer is a system that resists changes in pH when an acid or

         a base is added.

     B.  A buffer is prepared by mixing a weak acid with a weak base.

     C.  A buffer is prepared by mixing a strong acid and its conjugate

         base.

     D.  A buffer is prepared by mixing the salt of a strong acid with

         water.


 6.  When a strong acid is titrated with a strong base, the pH at the

     equivalence point


     A.  is equal to 7.

     B.  is greater than 7.

     C.  is less than 7.

     D.  cannot be determined from information given.


 7.  Calculate the pH of a solution of 25.0 mL of 0.250 M HNO3 after the

     addition of 40.0 mL of 0.300 M KOH.


     A.  1.05

     B.  7.00

     C.  12.95

     D.  13.48


 8.  In a 0.010 M solution of oxalic acid, H2C2O4,  Ka1 = 5.9 x 10-2,

     Ka2 = 6.4 x 10-5, the species present in the lowest concentration is


     A.  H2C2O4

     B.  H3O+

     C.  HC2O4-

     D.  C2O42-


 9.  How many mL of 0.200 M HNO3 are required to titrate 40.0 mL of

     0.500 Ca(OH)2 to the equivalence point?


     A.  16.0 mL

     B.  50.0 mL

     C.  200. mL

     D.  100. mL


10.  Determine the ratio of the concentration of formate ion to the

     concentration of formic acid in a solution of pH = 4.22.  Ka for

     formic acid = 1.8 x 10-4.


     A.  1/3

     B.  3/1

     C.  1/2

     D.  2/1


11.  What is the pH at the equivalence point when 50.0 mL of 0.500 M

     CH3COOH is titrated with 0.500 M NaOH?  (The Ka of CH3COOH is

     1.8 x 10-5).


     A.  4.74

     B.  9.26

     C.  7.00

     D.  9.07


12.  Which one of the following indicators would be most appropriate to

     use for the titration of a strong acid with a strong base?


                    Name                  pH range of color change


     A.        Thymol blue                    1.2 - 2.8

     B.        Methyl red                     4.2 - 6.3

     C.        Phenolphthalein                8.3 - 10.0

     D.        Alizarin yellow               10.1 - 12.0


13.  Which of the following substances will be more soluble in acid

     solution than in pure water?


     A.  CaCO3

     B.  (NH4)2SO4

     C.  BaCl2

     D.  KBr


14.  One of the purposes of thermodynamics is to learn about a reaction's


     A.  spontaneity.

     B.  mechanism.

     C.  rate.

     D.  stoichiometry.


15.  A measure of the randomness of a system is best given by its


     A.  enthalpy.

     B.  entropy.

     C.  free energy.

     D.  equilibrium constant


16.  A spontaneous change is always accompanied by an increase in


     A.   delta Hsystem

     B.   delta Ssystem

     C.   delta Ssurroundings

     D.   delta Suniverse


17.  Which one of the following statements is true for any chemical

     system at equilibrium at constant temperature and pressure?


     A.   delta H = T delta S

     B.   delta G = T delta H

     C.   delta G = delta S

     D.   delta H = delta S


18.  For the equilibrium reaction


PCl5(g)   =  PCl3(g)  +  Cl2(g)


     delta Ho = +92.5 kJ and delta So = +182 J/K at 773 K.  What is

     delta Go for the reaction at 773 K?


     A.   48.2 kJ

     B.   1417.7 kJ

     C.   0.0 kJ

     D.   54170.8 kJ


19.  Which one of the following represents the reaction corresponding

     to the standard heat of formation of BaCO3?


     A.  Ba(s)  +  C(graphite)  +  O3(g)  =  BaCO3(s)

     B.  Ba(s)  +  C(graphite)  +  3 O(g)  =  BaCO3(s)

     C.  2 Ba(s)  +  2 C(graphite)  +  3 O2(g)  =  2  BaCO3(s)

     D.  Ba(s)  +  C(graphite)  + 3/2 O2(g)  =  BaCO3(s)


20.  What is the vapor pressure of Br2(l) at 25oC (298 K) if delta Go

     for the following reaction is 3.14 kJ/mol?


Br2(l)   =   Br2(g)


     A.  0.28 atm

     B.  1.00 atm

     C.  3.55 atm

     D.  0.76 atm


21.  Which of the following statements is true?


     A.  If delta Go > 0, K > 1.

     B.  K = e delta Go/RT.

     C.  If K = 1, delta Go = 0.

     D.  If delta Ho < 0 and delta So < 0 the reaction will be spontaneous

         at very high temperatures.


22.  For which of the following is delta Ssys < 0?


     A.  CO2(s)  =  CO2(g)

     B.  NH3(g)  +  HCl(g)  =  NH4Cl(s)

     C.  NaCl(s)  =  Na+(aq)  +  Cl-(aq)

     D.  CO(g)  +  H2O(g)  =  CO2(g)  +  H2(g)


23.  Four processes are characterized by the sign of delta H and

     delta S in the  table below.  Which one of these processes cannot

     be spontaneous at any temperature?


             delta H     delta S


     A.        -            -

     B.        +            +

     C.        +            -

     D.        -            +


24.  At 25oC delta Go for the reaction


H3O+(aq)  +  OH-(aq)  =  2 H2O(l)


     is -79.9 kJ.  What is the equilibrium constant for the following

     reaction?

2 H2O(l)  =  H3O+(aq)  +  OH-(aq)


     A.  K = 1.0 x 1013

     B.  K = 1.0 x 1014

     C.  K = 1.0 x 10-14

     D.  K = 1.0 x 10-13


25.  Calculate the value of  delta Go and determine if the following

     reaction is spontaneous.


Fe2O3(s)  +  2 Al(s)  =  Al2O3(s)  +  2 Fe(s)


          Substance       delta Gfo (kJ/mol)


          Al2O3(s)           1582.3

          Fe2O3(s)            742.2


     A.  delta Go = +840.1 kJ/mol,  spontaneous


     B.  delta Go = -840.1 kJ/mol,  spontaneous


     C.  delta Go = -840.1 kJ/mol,  non-spontaneous


     D.  delta Go = +840.1 kJ/mol,  non-spontaneous


2 April 1996