Note: This exam may contain questions from chapters that will not be covered by the inclass exam and those questions should be ignored

Exam 2 PRACTICE                 Chem 1B                   Name ________________________

DH°=DHf°(products)-DHf°(reactants)                   DG°=DGf°(products)-DGf°(reactants)

DS=DS°(products)-DS°(reactants)             DG=DG° +2.303RTlogQ           DG°=DH°-TDS°

DU=q+w              w= -PDV            DS=q/T
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DG=-nFE           E = E° - (.059/n)xlog Q             Q = {products}/{reactants}

Al3+ + 3e- -------> Al -1.71 V            V = w/Q            Q=It            1A=1C/s

Zn+2 + 2e- ------> Zn -0.76 V             F = 96,500C/mole e-

Fe+2 + 2e- ------> Fe -0.41 V

Cu+ + 1e- -------> Cu 0.52 V
-------------------------------------------------------------------------------------------------------------- DHf°       DGf°          S°       All values are in kJ
N2         0               0          .1915

H2       0               0          .1306

NH3  -45.9        -16.0      .1930

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Exam 2 PRACTICE                Chem 1B                       Name ________________________
1    Fill in the blanks. a) All carbonates are _________________ except ________________, ________________ and ________________. All nitrates are ________________ except ________________. All halides are _________________ except _________________, _________________ and __________________. All sulfates are ___________________ except ___________________, _____________________, ____________________ and _____________________. All hydroxides are ____________________ except __________________, ________________ and __________________. All sulfides are _________________ except __________________, __________________ and _________________.

2       Saturated Ca(OH)2 has a pH of 12.35. Calculate Ksp.
 
 
 

3        A 60.0 ml sample of .010 M Pb(NO3)2 was added to a beaker containing 40.0 ml of .040 M KCl. Will precipitate form. Ksp = 1.6x10-5.
 
 

4        What pH must be present to make a maximum separation of zinc ions and copper ions in a saturated H2S solution? Assume that both concentrations are .1 M initially. , [H2S]= .10 M, K1K2=KaH2S=1.1x10-20, Ksp(ZnS)=1.1x10-21, Ksp(CuS)= 6x10-36
 
 
 
 
 

  • .050 moles of AgNO3 is dissolved in 1.00 L of 6M NH3. What is the [Ag+]?

    •  

     
     
     
     
     
     
     
     
     
     

    6        a) At what temperature will the reaction 3H2 + N2 --> 2NH3 become nonspontaneous assuming DS° and DH° are constant
     
     

    b) What is the equilibrium constant at 300°C for the Haber process?
     
     
     
     

    7        Calculate the entropy change in kJ when 10.00 kg of water slowly (near equilibrium) melts at 0.0°C. DHf= 79.6 cal/g, 1 cal=4.184 J
     
     
     
     
     
     

    8        Balance each equation and circle the best choice for the sign or magnitude of DS°.

    H2O(l) --->        H2 +        O2        Positive / Negative / About Zero

    H2O(g) --->        H2O(s)               Positive / Negative / About Zero

    H2O(g) +        CO2(g) --->        O2 +        CH4(g)        Positive / Negative / About Zero

    Na(s) +        H2O(l) --->        NaOH +        H2        Positive / Negative / About Zero

    HgO(s) --->        Hg(l) +        O2        Positive / Negative / About Zero
     

    9        a. Draw a battery cell for the Al-Zn chemical system and label the anode,

    the cathode, the plus and minus terminals, the direction of ion flows across the

    salt bridge and the direction of electron flow through the connecting wire.
     
     
     

    b. What is the equilibrium constant for the chemical reaction?
     
     
     

    c.  If the if all original ion concentrations were 1.00 M, then what would the voltage of the battery be if 99.9% of the reactants are consumed?
     
     
     
     
     
     

    d. What is DG for the reaction under standard conditions and after 99.9% of the reactants have been consumed? RTFQ
     
     
     

    e. If 2.00 A flows through the cell for 6.00 hours, what is the change in mass of aluminum electrode.
     
     
     

    10       List three ways in which an electrolytic cell differs from a galvanic cell?
     
     
     
     
     

    11       What is the maximum voltage battery you can make from the ions given on the first page?
     
     
     
     
     

    12        A sample of burned wood (Carbon) was found in a ancient fire pit. 1.00 g of this sample gave 2150 electrons emitted per second. A 1.00 g of pure fresh carbon gave 3160 electrons emitted per second. Give the year when the tree was alive.

    t1/2=5730 years. Hint: BC
     
     
     
     

    13        Predict the type of radiation each nuclei is expected to give and balance the equation.

     

    14060Pd                                                          18901Hg
     
     

    49Be                                                               2122Mg
     
     

    14        1.00 kg of hydrogen reacts to form helium according to the equation:

    4 11H ---> 42He + 2e+ + energy. How much energy is released?

    Note: me+= me-
     
     
     

    16    Give equations showing how each alkali metal is formed from suitable starting material
    Give three uses of Pb ________________________, ___________________________,

    ___________________________

    17        Give three uses of N2________________________, ________________________,

    ________________________

    18        Give the anode and cathode equations for the Hall-Heroult process.
     
     
     
     
     
     

    19        What are the formulas for the anhydrides of the following acids and bases?

    H3PO4, NaOH, HClO3, Al(OH)3, H2SO4
     
     

    20        Balance the following equations.

    20        Balance the following equations. Look em up!
    Al2O3 + H2O + OH- ----->                                     Mg + O2 ---->
     
     

    Al2O3 + HCl ---->                                                   Br2 + O2 ---->
     
     

    K + O2 ---->                                                            Br2 + H2O ---->
     
     

    Al + H2O ---->                                                        NO2 + H2O ---->
     
     

    Be + H2O ---->                                                       NO + H2O ---->
     
     

    Mg + H2O ---->                                                        Be + O2 ---->
     
     

    CaO + H2O ---->                                                     Ca + H2O ---->
     
     

    SO2 + H2O ---->                                                     Ca + O2 ---->
     
     

    P2O5 + H2O ---->                                                  C + H2O ---->

    21        Al2O3 is treated with alkali to dissolve the solid. The solution is treated with acid to form a precipitate. The precipitate is heated strongly forming a white powder. This white powder is dissolved in cryolite and placed in a carbon crucible with a carbon electrode and current is passed through it. Give all four equations for the above described process.