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									Chem 124                               Fall 2008                                Dr. Neff




                Chem 124 Workbook

  I recommend printing this out in sections rather than printing the entire document at
   once. You will work on some of these problems with your partner in class, so you
 should bring this workbook to every class. We will go over some problems together
    as a group, and solutions to some of the other problems MAY be posted online.
     Problems like these, as well as the suggested text problems, could show up on
                                  quizzes and/or exams .




 NOTE that you should work these out in your notebooks – there isn’t necessarily
             enough space to work the problems on these pages.
Chem 124                                     Fall 2008                                  Dr. Neff



                            Thermochemistry
    Read in Chapters 6, 12 and 20 as listed on online syllabus.


             Useful Equations that you need to memorize!

                                        E = q + w
                            ( at constant Pressure, E = H + PV )

                                  q = mcT               q = nH

                       Hrxn =  nHf (products) -  nHf (reactants)
                       Srxn =  nS (products) -  nS (reactants)
                       Grxn =  nGf (products) -  nGf (reactants)

                         G = H - TS
               
 Most Constants will be given to you on quizzes and exams – but
       you need to memorize c for water(l) = 4.184 J/g˚C


I will give you these constants on the quizzes & exams, others you may need for
                    the workbook can be found in text or online
                             Substanc           Specific Heat,
                                e                  J/g•K
                                Al                 0.900
                                Fe                 0.450
                                Cu                 0.387
                                Au                 0.129

           fusion of water = 6.02 kJ/mol               vaporization of water = 40.7 kJ/mol
Chem 124                                         Fall 2008                                           Dr. Neff


Internal E nergy, Calorimetry, E nthalpy, Phase Changes :
  1. What are the two main components of internal energy of a substance? What are the symbols for
     internal energy and its two components?


  2. A system which undergoes an adiabatic change is one in which no heat is transferred. For an
     adiabatic change that does work on its surroundings, indicate if q, w and E for such a process
     should be positive, negative, or equal to zero. Explain.


  3. For each of the following, define the system and the surroundings, and indicate the direction of
     heat transfer.
     a) Natural gas is burned in a gas furnace in your home.


     b) Water drops, sitting on your skin after a dip in the pool, evaporate.


  4. If you pour hot tea over a cup of ice, what are all the factors that will affect the final temperature of
     the mixture?


  5. Does a negative Hrxn mean that the heat of reaction can be thought of as a reactant or a
     product?


  6. a) What is the difference between an endothermic and an exothermic reaction or process? How
     does this relate to the sign of the enthalpy change for each process?

     b) Would the products or reactants of an exothermic reaction have higher thermal energy on an
     enthalpy diagram? Draw such a diagram to represent a generic exothermic reaction, making
     sure to label all keys features.


  7. The enthalpy of a reaction is related to the bond energies of the reactants and products, as we
     discussed in class. Do the reactants or products have greater bond energy (that is, stronger
     bonds) in an exothermic reaction? Explain.


  8. For the reaction

     CO (g) + NO (g) ----> CO2 (g) + 1/2 N2 (g)                   H = -373.3 kJ

           a) Which should go at higher energy on an energy level or an enthalpy diagram, the products
              or the reactants? Draw an energy level diagram that illustrates this reaction.
Chem 124                                             Fall 2008                                     Dr. Neff
           b) Which has stronger bonds, the products or reactants? Explain.

  9. If equal amounts of heat are added to equal masses of aluminum and copper, both at the same
     initial temperature, which will reach the higher final temperature? Explain your answer.


  10. The following diagram illustrates both temperature changes and the phase changes (solid liquid
       gas) that occur as you add heat to a substance. Each portion of the curve is labeled from A –
      E. Answer the questions below concerning this diagram.



                                                                  E
                                                           D
                   Temperature ˚C




                                                C                        2

                                        B                  1
                                    A



                                            Heat Added 

   a) Which portion of the curve corresponds to boiling (vaporization)?

   b) Which portion of the curve corresponds to heating the gas state?

   c) Which portion of the curve corresponds to the solid phase only?

   d) Is the process of going from point 1 to point 2 exothermic or endothermic? (Circle your answer.)


 11. The nutritional calorie (Calorie) is equivalent to 1kcal. One pound of body fat is equivalent to about
     4.1 x 1010 Calories. Express this energy equivalence in joules and kilojoules.


 12. Power is the term used to describe the amount of work done in a certain length of time. The
     common power unit in the automotive field is the horsepower (HP), where 1 HP = 550 ft-lb/sec =
     33000 ft-lb/min = 2545 BTU/hour. This unit was originated by James Watt, the inventor of the steam
     engine, to help describe the capabilities of these engines. A healthy adult human can sustain
     approximately 0.100 HP. Determine how many Joules of work a healthy adult human could
     potentially do in one hour.


 13. One piece of copper jewelry at 105°C has exactly twice the mass of another piece, which is at
     45°C. Both pieces are placed inside a coffee cup calorimeter whose heat capacity is negligible.
     What is the final temperature inside the calorimeter (c of copper =0.387 J/gK) once thermal
     equilibrium is reached?
Chem 124                                        Fall 2008                                         Dr. Neff
 14. Let’s say you want to make some hot tea. How much heat energy is needed to heat up 2 cups of
     water, or approximately 5.00 x 10 2 mL, from 22.0˚C to 95.0˚C?

 15. How many grams of solid copper metal, heated to 155˚C, would you need to heat the water in
     Problem 14?

 16. Let’s say you changed your mind about the hot tea in Problem 14 and decide you’d rather have
    iced tea. What is the final temperature of a mixture of that 5.00 x 10 2 mL of hot water at 95.0˚C and
    475 g of -12.0˚C ice cubes? (NOTE that in this process, the ice heats up to its melting point, melts,
    and then heats to the final temperature of the mixture. Given: c of ice is 2.06 J/g˚C, H˚fus = 6.01
    kJ/mol.)

 17. A 30.5g sample of an alloy at 93.0°C is placed into 50.0g of water at 22.0°C in an insulated coffee
    cup. If the final temperature of the system is 26.2°C, what is the specific heat of the alloy? Assume
    all heat transferred is done so between alloy and water only.

 18. A 280.0 g piece of gold was cooled to 0.0˚C in an ice bath. The gold piece was then dropped into
    a styrofoam cup containing 222 mL of water at 60.0˚C. What is the final temperature of the gold
    and the water after they come to thermal equilibrium? Assume the density of water is 1.00 g/mL for
    the temperature range of this problem, and that no heat is lost to the cup or surroundings.


Thermochemical Stoichiometry:
  19. Translate the following word statements into complete, balanced thermochemical equations.
       a) The complete combustion of acetylene (C 2H2), the fuel used in acetylene welding torches,
           produces carbon dioxide gas and water vapor and releases 1256 kJ of heat energy per
           mole of acetylene.

       b)   The net reaction involved in the destruction of ozone by chlorofluorocarbons is the reaction of
            monatomic chlorine gas (Cl) with ozone (O3) to produce chlorine monoxide gas and oxygen
            gas. This requires the input of 54 kJ of heat per mole of ozone.

       c)   The production of sulfuric acid rain can be broken down into three key steps. First is the
            combination of solid sulfur with oxygen gas to produce sulfur dioxide gas. This produces
            297 kJ of heat per mole of sulfur. The next step is the combination of sulfur dioxide gas with
            oxygen gas to produce sulfur trioxide gas. This reaction produces 98 kJ of heat per mole of
            sulfur dioxide gas reacting. Finally the sulfur trioxide gas combines with water vapor in the
            air to produce sulfuric acid. This produces 227 kJ of heat per mole of sulfuric acid produced.


20. Pure liquid octane (C 8H18, d= 0.702g/mL) is used as the fuel in a test of a new automobile drive train.
      a) How much energy is produced (in kJ) when a tank full (20.4gal) is combusted? Hcomb = -
                   3
           5.45x10 kJ/mol)? (Start with a balanced equation for the combustion of one mole of octane to
           make carabon dioxide and water.)


       b) The energy delivered at the wheels at 65mph is 5.5x 10 4 kJ/h. Assuming that all the energy is
          transferred to the wheels, what is the cruising range of the car (in km) on a full tank?
Chem 124                                        Fall 2008                                         Dr. Neff

21. Consider the following reaction, which several of you observed in lab last week:
                            2 Mg(s) + O2(g) --> 2 MgO(s);       H = -1204 kJ
   (a) Is this reaction endothermic of exothermic?

   (b) Calculate the amount of heat produced when 2.4 g of magnesium reacts at constant pressure.

   (c) How many grams of MgO are produced during an enthalpy change of 96.0 kJ?

   (d) How many kilojoules of heat are absorbed when 7.50 g of MgO are decomposed into magnesium
   and oxygen at constant pressure?


22. Lightweight camp stoves often make use of a mixture of C 5 and C 6 liquid hydrocarbons (a fuel called
   “white gas.”) How much heat is produced by the complete combustion of 3.00 L of C 5H12 (l) given that
   the enthalpy of combustion is approximately -3540 kJ per mole of C 5H12 (l).
  (Given: density of C 5H12 (l) = 0.625 g/mL)


Combination or Synthesis Problems :
  These problems combine two or more concepts, like stoichiometry and calorimetry. Expect at least
  one problem like this per exam!

23. a) How much C 5H12 (l) in both g and mL would you need to combust in order to produce enough
   heat to heat up the water in Problem 14, that is, 2 cups of water, or approximately 5.00 x 10 2 mL,
   from 22.0˚C to 95.0˚C? Assume that all the heat from the combustion directly goes to heating the
   water, no heat is lost to the surroundings.

   b) Given that the complete combustion of propane (C 3H8) produces approximately 2220 kJ of heat
   per mole of propane, how much C 3H8 in both g and mL would you need to combust in order to
   produce enough heat to heat up the water a) above (& Problem 14)? Assume that all the heat from
   the combustion directly goes to heating the water, no heat is lost to the surroundings. (Density of C 3H8
   = 0.494 g/mL)

   c) You’re going camping and have to carry all your supplies in to your camp ~10 miles uphill from
   where you park your car. You’d like to take a fuel source with you for cooking, but want to carry as
   little extra weight as you can. Given what you learned in problems 22 & 23, which fuel would rather
   carry with you, propane or pentane (C 5H12)? Explain your choice.


24. Some cold packs used to treat athletic injuries have a small pouch of ammonium nitrate, that when
   squeezed, dissolves in the surrounding water. This dissolving pulls in heat from its surroundings, to
   lower the temperature of the pack, according to the following thermochemical equation:
                     NH4NO3 (s)  NH4NO3 (aq)                   Hrxn = +25.7 kJ
   What is the final temperature in ˚C in a squeezed cold pack that contains 25.0 g of NH4NO3 (s),
   dissolved in 125 mL of H2O (l), at an initial temperature of 25.0˚C? Assume no heat is lost to the
   environment, all heat transfer is between the system and surrounding water, and that the density of
Chem 124                                          Fall 2008                                       Dr. Neff
   water is 1.00 g/mL. Also assume that the specific heat capacity of the dissolved ammonium nitrate in
   water is the same as that of water.
E nthalpies of Formation
25. Write balanced chemical reactions for the formation of one mole of each of the following compounds
from its elements in their standard states:

       a) Liquid water

       b) Aqueous strontium nitrate

       c) Solid iron (III) bromide

       d) Solid aluminum oxide

       e) Solid magnesium phosphate


26. The space shuttle orbiter uses the oxidation of methyl hydrazine by dinitrogen tetroxide for propulsion.
    The unbalanced reaction is as follows:
              N2H3CH3 (l) +            N2O4 (l)            H2 (g) +        N2 (g) +   CO2 (g)
       a)    Balance this equation.
       b)    Calculate H˚rxn for this reaction using the following info:

                   Substance                H˚f (kJ/mol)
                     N2O4 (g)                   9.16

                      N2O4 (l)                  -20.0

                   N2H3CH3 (l)                   54.0
                      CO (g)                    -110.5
                     CO2 (aq)                  - 412.9

                      CO2 (g)                   -393.5



   27. The major reactions occurring in a blast furnace during isolation of iron from its major ore are
   shown below. Starting with iron(III) oxide (the major constituent of iron ore), one eventually ends up
   with iron metal. Use standard enthalpies of formation found in Appendix B of your text to calculate the
   enthalpy of each of the three reactions shown below.

                                     3 Fe2O3 (s) + CO (g)  2 Fe3O4 (s) + CO2 (g)

                                      Fe3O4 (s) + CO (g)  3 FeO (s) + CO2 (g)

                                         FeO (s) + CO (g)  Fe (l) + CO2 (g)
Chem 124                                         Fall 2008                                        Dr. Neff




Hess’s Law
28. Now add up the three reactions in the previous problem to get the net reaction, and calculate the
  enthalpy of this net reaction in kJ per mole of iron metal produced, using Hess’s Law.


29. Given the following data calculate H for the reaction N2O(g) + NO2(g) --> 3 NO(g)

                             N2(g) + O2(g) --> 2 NO(g);          H = +180.7 kJ
                             2 NO(g) + O2(g) --> 2 NO2(g);       H = -113.1 kJ
                             2 N2O(g) --> 2 N2(g) + O2(g);       H = -163.2 kJ


30. The bombardier beetle uses an explosive discharge as a defensive mechanism. The chemical
   reaction involved is the oxidation of hydroquinone by hydrogen peroxide to produce quinone and
   water, as shown below:

              C 6H4 (OH)2 (aq) + H 2O2 (aq)  C6H4O2 (aq) + 2 H 2O (l)

       Calculate H for this reaction from the following data. Show all you work explicitly!

       C6H 4(OH)2 (aq) +  C6H4O2 (aq) + H 2 (g)                 H = 177.4 kJ

       H2 (g) + O2 (g)  H2 O2 (aq)                                      H = -191.2 kJ

       H2 (g) + 1/2 O2 (g)  H2O (g)                             H = -241.8 kJ

       H2 O (g)  H 2O (l)                                       H = -43.8 kJ


31. One problem with using hydrogen as a fuel is producing enough hydrogen efficiently. One series of
    reactions being studied has as its net reaction the splitting of liquid water:

              H 2O (l)  H2 (g) + 1/2 O2 (g)                     H˚rxn = 285.8 kJ

   This series of reactions involves each of the following steps in some form. Use Hess’s Law to
   calculate the missing H˚rxn. (HINT on how to get started – figure out how the following reactions must
   be manipulated to add up to give you the above reaction, then you should be able to easily calculate
   the missing H˚rxn.)

                  H 2 (g) + I2 (g)  2HI (g)                                     H˚rxn = -10.64 kJ
    H2O (l) + 1/2 SO2 (g) +1/2 I2 (g)  1/2 H 2SO4 (aq) + HI (g)                 H˚rxn = ?
      2 H2O (l) + 2 SO2 (g) + O2 (g) 2 H 2SO4 (aq)                              H˚rxn =-649.82 kJ
Chem 124                                                 Fall 2008                                                 Dr. Neff

(NOTE that this particular system is inefficient as one reaction requires a temperature of 825˚C. The goal of some research i n
this area is to find a system that requires low enough temperatures that sunlight can be used as an energy source)




Summary Problem

The thermite reaction (also known as the Goldschmidt reaction, for its inventor), shown below, has a
variety of uses, including repair welding of such things as railroad tracks or automotive axles. This same
reaction has been used in grenades and other incendiary devices in times of war, as it generates enough
heat to burn through heavy armor. It can also occur accidentally in industrial locations where there is a
combination of aluminum metal, iron compounds, and some sort of abrasive grinding or cutting wheels
being used. It is an extremely dangerous reaction, reaching temperatures up to 2500˚C. Since the
mixture of Al and Fe2O3 has its own supply of oxygen, it cannot be extinguished by smothering to block
out oxygen in the air, and it can potentially ignite in any environment. Any water poured onto the reaction
to attempt to extinguish is instantly boils. It burns as well underwater as it does in air, also making it using
for undersea welding. (It was also featured recently on an episode of “MythBusters” wherein they
investigated this reaction as the real “cause” of the fire that destroyed the Hindenberg.)

          2 Al (s) + Fe 2O3 (s)  Al2O3 (s) + 2 Fe (s)                      H˚=?

    a) Use standard enthalpies of formation found in Appendix A of your text or another source to
    calculate the standard enthalpy of this reaction.




    b) If 45.0 g of aluminum metal is reacted with excess iron (III) oxide, how much iron metal can be
    produced, assuming complete reaction?




    c) Will the complete reaction of this 45.0 g of Al via the thermite reaction generate enough heat to
    melt all the iron that is produced? Assume the iron produced is already at its melting point, and
    assume no heat is lost to the surroundings (complete heat transfer from reaction to Fe).




    d) Assuming complete reaction and complete heat transfer, exactly how many grams of iron will the
    thermite reaction of 45.0 g of Al melt?
Chem 124                                           Fall 2008                                   Dr. Neff




E ntropy, Free E nergy
32. Define entropy in your own terms. Then list the conditions under which entropy INCREASES.


33. Which member of each of the following pairs has the greater amount of entropy?
    Circle your choice and explain in each case.
                              CO2 (g) or CO2 (s)        NH3 (l) or H2NNH2 (l)

                              1 mole of HCl (g) or     H2(g) at 25˚C or H2(g) at
                               1 mole of HBr (g)                 100˚C
                              both at same temp.

                                  He (g) at 1 atm or   A building in its “normal”
                                   He (g) at 2 atm     state or a building after
                                                              demolition

34. For each of the following processes or reactions, indicate whether you would expect the entropy of
   the system to increase or decrease. If you cannot predict from the given information explain why.
       (a) A solid sublimes

       (b) A liquid freezes

       (c) AgI precipitates from a solution containing Ag + and I- ions

       (d) Gaseous CO2 bubbles out of a carbonated beverage

       (e) CH3OH(l) --> CH3OH(g)

       (f) N2O4(g) --> 2NO2 (g)

       (g) CO(g) + H2O(g) --> CO2(g) + H2(g)

       (h) 2KClO3(s) --> 2KCl(s) + 3O2 (g)

       (i) 2NH3 (g) + H2SO4 (aq) --> (NH4)2SO4(aq)


35. Complete the following table by putting a response in the product-favored column. If your answer
   depends on a variable, list the conditions of your response.
Chem 124                                        Fall 2008                                        Dr. Neff

                    Hsystem         Ssystem     Sign of G system Spontaneous?
                     negative        positive
                     negative        negative
                     positive        positive
                     positive        negative
36. Reactions sometimes have the factors enthalpy and entropy both favorable, or both unfavorable, and
    at other times only one is favorable. This results in the conclusions listed in A-D below. Consider the
    reaction below and without reference to any data tables, draw the proper conclusion on which
    condition A-D best represents the reaction being spontaneous as written.

             SrO(s) + C (s) (graphite) --> Sr (s) + CO (g)                   H = +560 kJ
       A. The reaction would be spontaneous at all temperatures.
       B. The reaction would be spontaneous at lower temperatures but not at higher temperatures.
       C. The reaction would be spontaneous at higher temperatures but not at lower temperatures.
       D. The reaction would not be spontaneous at any temperature.

       Briefly explain your logic.


37. Consider the following spontaneous gas phase reaction of A 2 molecules (open circles) and B 2
molecules (filled circles):




      (a) Write a balanced equation for the reaction.


      (b) What are the signs (+, -, or 0) of H, S, and G for the reaction? Explain your answers.


38. Look up or predict the sign of the enthalpy for each of the following reactions. Then predict the sign
of the entropy change for each. Then explain the given G in light of the enthalpy and entropy predictions
you’ve made.

            a) H2(g) + 1/2O2(g)  H2O(g)                        G = -228.6 kJ

         b) C 3H8(g) + O2(g)  CO2(g) + H2O(g) G = -546 kJ             unbalanced!
Chem 124                                             Fall 2008                                  Dr. Neff
39. As discussed in previous problems, the dissolving of ammonium nitrate in water is used in some
cold packs. Find the Gibbs free energy of this process at 25˚C from the information below:

                                   NH4NO3(s)  NH4NO3(aq)
            Hf˚ (kJ/mol)                 -356.5               -339.9
            S˚ (J/K•mol)                  151.1                259.8

40. Metallic iron is produced by a high temperature process through a series of reactions, one of which
is shown below. Find the various parameters requested using the data which can be found below.
                            3Fe2O3(s) + CO(g)  2Fe3O4(s) + CO2(g)
   a) Find the change in enthalpy for the reaction under standard thermodynamic conditions.
   b) Find the change in entropy for the reaction under standard thermodynamic conditions.
   c) What is change in free energy for the reaction under standard conditions?
   d) Under standard conditions, the reaction is (circle all that apply):

 Exothermic or Endothermic?               Enthalpy-Driven or Entropy-Driven or both?
                              Product-Favored or Reactant-Favored?

                                                   Given Data
                                                   ∆H˚f (kJ/mol)        S˚ (J/K•mol)
                              Species
                               CO2(g)                 -393.5               213.7

                               CO(g)                  -110.5               197.5
                               H2O(g)                 -241.8               188.7
                              Fe3O4(s)                -1121                145.3
                               H2O(l)                 -285.8               69.94
                              Fe2O3(s)                -825.5               87.40
                              CH4O(l)                 -238.9                127
                              C2H6O(l)               -277.63                161
                              C8H18 (l)               -255.2               329.3
                             C(diamond)               1.896                2.439


Combo/Synthesis Problem
41. a) Many metal oxides are “smelted” with carbon or carbon monoxide to “free” the metal, which may
need to be condensed to the solid for use. Use the following information to determine the enthalpy for the
net step in the production of molten tin from one of its oxides:
                     SnO2 (s) + 2 C (s)  Sn (l) + 2 CO (g)                            H = ?

       Given information:
                    SnO (s) + CO (g)  SnO2 (s) + C (s)                      H = -189.5 kJ
                2 Sn (l) + 2 CO2 (g)  2 SnO (s) + 2 CO (g)                  H = 460.0 kJ
                    CO2 (g) + C (s)  2 CO (g)                               H = 172.5 kJ
Chem 124                                             Fall 2008                                                Dr. Neff
    b) How many kJ of heat would be required to produce 157 g of molten Sn in the net reaction above?


   c) Would you expect the net reaction be spontaneous or nonspontaneous? Explain.



                                           Chapter 7-8
           Quantum Theory & Periodic Properties

Problems like these, as well as the suggested text problems, could show up on quizzes and/or exams. A
KEY may be posted online.

        Equations and Constants you should know how and when to use!

                         These two you must memorize, they both relate to light:

                                        c                       E  h

                                                                                                  h
                 This one doesn’t relate to light. When should you use it?                   
                                                                                                  mu

       These three should be used for calculations involving transitions in the hydrogen atom only:
                                         1                                               1 1 
                                      J  2                                            J  2 - 2 
                                -18                                                 -18
               E = -2.18 x 10           n                 E = -2.18 x 10                n n 
                                                                                         f   i 



                         1      1   1 
                           = R  2  2  where n > n1 , R 1.097 x 10 m-1
                                         ,                            7

                              n1 n2 
                                                  2




                                                                                                  h
               This one quantitatively describes what principle?               x  mu 
                                                                                                4

Do you know what all the variables represent in this one?           E photon =  + K.E.electron


                                                                              -34
                             Planck’s constant               h = 6.626 x 10         J•s
                                                                                                          8   -1
       You need to memorize this one:                  Speed of light                     c = 3.00 x 10 m•s

               Memorize this one too:             Avogadro’s Number = NA = 6.02 x 1023 mole-1

                                        electron mass = 9.11 x 10-31 kg

                                        proton mass = 1.67 x 10–27 kg
     
Chem 124                                        Fall 2008                                      Dr. Neff

                                      neutron mass = 1.67 x 10-27 kg

 This list does not include any conversion factors, but that doesn’t mean you don’t need to know some! I
  will give you English to metric conversions, but you need to know how to convert between metric units
                                          (eg, from m to nm, etc).


1. a) On the diagram below, label the following characteristics of a light wave:

                            Wavelength, 
                            Amplitude
                            Node




b. In the diagram below, draw in each of the following. Make sure you label each new wave!
            a) A wave with shorter wavelength
            b) A wave with smaller frequency
            c) A wave with the same wavelength and frequency but less amplitude.
Chem 124                                        Fall 2008                                         Dr. Neff




2. Consider the following types of electromagnetic radiation:
      i) microwave
      ii) ultraviolet
      iii) radio waves
      iv) infrared
      v) x-ray

      a) arrange them in order of increasing wavelength
      b) arrange them in order of increasing frequency
      c) arrange them in order of decreasing energy




3. Cobalt-60 is a radioactive isotope used to treat cancers of the brain and other tissues. A gamma
ray emitted by an atom of this isotope has a wavelength of 9.32 x 10 -13 m.

      a. What is this wavelength in nm?


      b. What is the frequency of this light in Hz?


      c. What is the energy of one photon of this light in J?


      d. What is the energy of one mole of these photons in J/mol?


      e. What is the energy of one photonof this light in electron volts eV (1 eV = 1.602 x 10 -19 J)?


      f. Does radiation with = 242 nm have greater or lesser energy than the radiation emitted by the
      gamma ray above? What about radiation with = 2200 Å (1 Å = 1 x 10-10 m)? (You shouldn’t
      need to do calculations to answer these questions)
Chem 124                                         Fall 2008                                        Dr. Neff
4. One watt (W) is equal to 1 J/s. Assuming that 5.0% of the energy output of a 75 W light bulb is visible
light and that the average wavelength of the visible light is 550 nm, how many photons are emitted by the
light bulb per second?




5. At its closest approach, Mars is 56 million km from earth. How long would it take to send a radio
message from a space probe of Mars to earth when the planets are at this closest distance? (hint: how
fast does light travel?)




6. Microwave ovens work by irradiating food with microwave radiation, which is absorbed and converted
into heat. Assume radiation with 
many photons are necessary to raise the temperature of a 350 mL quantity of water from 20.0˚C to
95.0˚C?




                                                                                                    5
7. On a Sunday morning while having your breakfast you determine that you need about 2.95 x10 J to
                                                   24
heat water for your tea in the microwave. If 2.5x10 photons hit the cup every second and you set the
timer to 2.4 min, what should the frequency of the microwave be so that the tea is ready in that time?




8. The photoelectric work function of a metal is the minimum energy needed to eject an electron by
irradiating the metal with light. For calcium, this work function equals 4.34 x 10 -19 J. What is the minimum
frequency of light required to observe the photoelectric effect in calcium?
Chem 124                                         Fall 2008                                        Dr. Neff
9. Light of wavelength 345 nm shines on a piece of calcium metal. What is the speed of the ejected
electron? (Light energy greater than that of the work function of calcium or any metal ends up as kinetic
energy of the ejected electron.)




10. a) Which of these transitions correspond to absorption and which to emission of radiation (or
energy in general)? Illustrate each transition on the provided energy level diagram.

   i) n = 2 to n = 4
                                                                                     n=5
                                                                                     n=4
   ii) n = 3 to n = 1
                                                                                     n=3


   iii) n = 5 to n = 2                              E                               n=2



   iv) n = 3 to n = 4
                                                                                    n=1



b) Of the transitions listed above, which corresponds to emission of radiation with the longest
wavelength? Explain. You should not need to use your calculator to answer this!


c) Of the transitions listed above, which corresponds to absorption of radiation with the highest
frequency? Explain. You should not need to use your calculator to answer this!



11. An electron in a hydrogen atom undergoes a transition from the n = 3 level to the n = 6 level. To
   accomplish this, energy, in the form of light, must be absorbed by the hydrogen atom.

           a) Calculate the energy of the light (in kJ/photon) associated with this transition. Watch the
              sign of your answer!
Chem 124                                          Fall 2008                                         Dr. Neff
           b) In order to move to the n = 5 level, would this same electron need to absorb more or less
              energy? Explain. You shouldn’t need to use your calculator here.




12. An electron in a hydrogen atom in the n = 5 level emits a photon with wavelength 1281 nm.
       a) To what energy level does this electron move?


        b) In order to move to the n = 1 level, will this electron emit a photon with longer or shorter
           wavelength than 1281 nm? Explain. You should not need to use your calculator here.




13. An electron in a hydrogen atom undergoes a transition from the ni = 6 level to some lower energy
level. In doing so, energy is released in the form of light.

   a) Calculate the frequency in s-1 (to 3 significant figures) of a photon of light associated with the
   highest frequency transition (i.e., largest difference in frequency) possible from the ni = 6 to a
   lower level. (HINT: Try drawing a picture first.)




        b) Calculate the wavelength (in nm) of this photon of light.




14. The emission lines of one-electron atoms and ions can all be fit to the equation describing the
spectrum of the hydrogen atom:
                                           1 1 
               E  (2.18 x 10 18 J) Z 2  2  2       where Z is the atomic number.
                                           f ni 
                                           n

           a. Calculate the energy (in J) of the photon associated with the transition of the electron in He +
              from n=2 to n=1.
   


           b. As the value of Z increases, does the wavelength of the photon associated with the
              transition from n = 2 to n=1 increase or decrease? Explain.
Chem 124                                        Fall 2008                                         Dr. Neff




15. Two objects are moving at the same speed. Which (if any) of the following statements about them
are true?
          c. The wavelength of the heavier object is longer.
           d. If one object has twice as much mass as the other, its wavelength is one-half the
              wavelength of the other.
           e. Doubling the mass of one of the objects will have the same effect on its wavelength as
              does doubling its speed.




                                                                                 6
16.The speed of the electron in the ground state of the hydrogen atom is 2.2 x 10 m/s. What is the
wavelength of the electron?




17. Calculate the wavelength of the Earth (mass 6.0 x 10 27 g) moving through space at 3.0 x 104 m/s.




18. At what speed must a human weighing 150. lb. be traveling in order to have a wavelength in the
visible region, say at 650 nm? Does it seem likely that a human would attain such a speed?




19. What is the momentum of a photon with a wavelength of 532 nm? (Remember to include the correct
units with your answer!)




                                                                                         h
20. Heisenberg's uncertainty principle can be expressed mathematically as x • mu        , where ∆u
                                                                                        4
and ∆x represent the uncertainty in the speed and the position and h is Planck's constant.
Chem 124                                         Fall 2008                                         Dr. Neff
Assume that you are traveling at a speed of 90.0 km/hr in a small car with mass of 1250 kg. If the
uncertainty in the velocity of the car is 1.00% of the speed you’re traveling, what is the uncertainty in
meters of the position of the car? Compare this to the uncertainty in the position of an electron (x ~ 3 x
10-10) and correlate each uncertainty with the size of the object (that is, for which object should you be
more certain about its position, the larger or smaller object? Is this what your calculation shows?)




21. Fill in the following table:

               Quantum             Orbital or Electron             Allowed Values
               Number                   Property
                    ml


                                    energy level and size


                                        orbital shape


                    ms




22. a) If the principal quantum number n of an atomic orbital is 4, what are the possible values
of l ?




b) If the angular momentum quantum number l is 3, what are the possible values of m l ?
Chem 124                                           Fall 2008                                        Dr. Neff
23. Explain why each of the following sets of quantum numbers would not be permissible for an
electron in an atom. Also make a correction that makes each set valid.

a) n = 1, l = 0, ml = 0, ms = +1


b) n = 1, l = 3, ml = +3, ms = +1/2


c) n = 3, l = 2, ml = +3, ms = -1/2


d) n = 0, l = 1, ml = 0, ms = +1/2




24. Identify the pictured orbital as s, p or d (write your answer next to the picture) and then answer the
following questions:




a. What is the l value for this type of orbital?

b. Can this type of orbital be found in the n = 2 energy level? If not, explain why.



c. List one complete and valid set of allowed quantum numbers for an electron occupying this type of
orbital in the n = 4 level.



d. How many nodal planes are found within this type of orbital?


25. In what way are the electron configurations of H, Li, Na, K, Rb and Cs similar? In what way are the
electron configurations of O, S, Se, Te and Po similar?
Chem 124                                          Fall 2008                                      Dr. Neff




26. Identify the following atoms or ions:

       a) It has the ground-state configuration [Ar] 4s23d104p1

       b) It has the ground-state configuration [Kr]4d10

       c) It forms a –3 ion that is isoelectronic with Kr

27. Write out BOTH the full electron configuration and the abbreviated electron configuration for each of
the following. Predict if the atom would be paramagnetic or diamagnetic.
         a.    31 Ga                       b. 42Mo                    c. 79Au




        For this one, write out just the abbreviated configuration.
        d. 98Cf




28. For each of the atoms listed in the problem above, give the number of inner (core) and outer
(valence) electrons and then list a set of quantum numbers representing an electron of highest energy
(one of the last electrons to fill).




29. Shown in the table below are various elements with a corresponding list of possible quantum
numbers for the "last" electron(highest energy) entering the atom. Check() the appropriate column if the
quantum "address" for the electron is correct. Circle the incorrect quantum number(s) if the quantum
"address" is incorrect.

             Element         n=             l=          ml =          ms =   Correct "address"
                7N            2             1               0         1/2

               14Si           3             1               1         -1/2
              45Rh            5             2               -2         1
              37Rb            6             0               0         1/2

              64Gd            4             3               -3        -1/2



30. Draw the electron orbital box diagram for each of the following neutral atoms, and indicate whether
they are paramagnetic or diamagnetic:
Chem 124                                         Fall 2008                                        Dr. Neff

a) Ge




b) Ca




31. Arrange the following elements in order of increasing effective nuclear charge, decreasing atomic
radii (size), increasing 1st Ionization Energy, increasing electron affinity, and decreasing metallic
behavior:

              C, F, Li, K, O



32. How does the size of a cation compare to the size of the corresponding atom? How does the size of
an anion compare to the size of the corresponding atom? Explain both.




                          Solid State Chemistry Workbook

A lot of what we’ll cover on this topic is NOT in the textbook, so your class notes may be your only source
of content information or example problems. Therefore, for the next couple of weeks, class attendance
and participation is more important than usual. The following problems are examples of content you are
expected to know and calculations you should be able to perform.


1. Find the repeating square unit cells in each of the following patterns.
Chem 124   Fall 2008   Dr. Neff
Chem 124                                         Fall 2008                                       Dr. Neff
2. In each of the cases shown below, draw z-diagrams for the unit cells shown and determine the net
number of atoms per unit cell.

a) Nickel, as well as many other metals, crystallizes in the structure shown below




b) Polonium is the only element known to crystallize in the structure shown below.




c) Iron, as well as many other metals, crystallizes in the structure shown below




d. Shown in the figure below is the unit cell structure for one form of C, the diamond structure. Also
shown is the corresponding z-diagram for this unit cell. Using this z-diagram, determine the contribution
of atoms to each z-layer, and from this, determine the net number of atoms contained within one unit cell.




                                                                                                        25
Chem 124                                              Fall 2008                                      Dr. Neff
3. Find the simplest formula for the following unit cell structure. Put the “elements” in the formula in
alphabetical order.




         z=0, 1   z= 0.25    z = 0.5       z = 0.75


KEY: A                B                C



4. a) Draw a set of z-diagrams for a unit cell having the hypothetical formula M2 N. Be sure that the unit
cell is a cubic variant and has a regular structure. Remember that the bottom (z = 0) and top (z = 1)
layers must be the same. Note that there is probably more than one way to draw z-diagrams to represent
such a structure.




b) Give the chemical formula for an ionic salt that might have the formula in the previous problem. Use
the periodic table to help you. (M is a metal, N a nonmetal.) Then name this compound using standard
chemical nomenclature rules.




c) Try to calculate the edge length of the unit cell you have postulated using your model salt and its cell
structure.




5. The metallic radius of manganese is 127 pm. If it crystallizes in a body-centered cubic unit cell, what
is its density in g/cm3?




                                                                                                              26
Chem 124                                           Fall 2008                                      Dr. Neff



6. Silver, Ag, crystallizes in the unit cell structure shown below.

Identify this unit cell type.


How many net atoms are contained in one unit cell of this type?




What would the edge length be for this unit cell type? (Determine this using geometry, don’t just look it
up!)



If Ag has a density of 10.5 g/cm3, what is the radius of a Ag atom in pm?




7. Europium is one of the lanthanide elements used in TV screens. Europium crystallizes in a unit cell
with coordination number of 8 and an edge length of 240.6 pm. Calculate the radius of a europium atom.




8. You are given a small bar of an unknown metal. You find the density of the metal to be 10.5 g/cm 3. An
X-ray diffraction experiment measures the edge of the face-centered cubic unit cell as 4.09 Å. (1 Å = 1 x
10-10 m). Identify this metal.




                                                                                                            27
Chem 124                                         Fall 2008                                        Dr. Neff

9. Calculate the edge length of the unit cell of NaCl on the basis on of the average radii of Cl - (181 pm)
and Na+ (98 pm) assuming that the corner Cl- ions and the Na+ along the edges touch (see figure below).




10. Lithium chloride crystallizes with the same structure as NaCl except that the chloride anions touch
along the face diagonal of the unit cell. If the unit cell edge is 513 pm, what is the radius of a chloride
ion? (hint – use the Pythagorean theorem…what is the face diagonal equal to given the first sentence of
this problem?)

11. For each of the following pictures of unit cells for ionic compounds, draw corresponding z-diagrams.
For all of these, determine the correct ionic formula for the compound and name the ionic compound.
a.




Key:          Ti            O




b.




Key:          Cd            I
                                                                                                         28
Chem 124                                        Fall 2008                                       Dr. Neff
12. The unit cell of rhenium oxide consists of a cube with rhenium atoms at the corners and an oxygen
atom on each of the 12 edges. What is the formula for rhenium oxide (rhenium is Rh)? What charge
must the rhenium ion have in this compound? Could you draw the z-diagram to illustrate the unit cell
described above?




13. Identify each of the following band structures as belonging to either a conductor, semiconductor or
insulator. In each structure, label the valence and conduction bands, the band gap, and give
representative values of the band gap for each.

a)                                        b)                           c)




E




14. A compound has the following band diagram, with the shading representing occupancy by electrons.
This solid has a completely filled lower energy band and a partially filled higher energy band. The energy
gap between the two bands is equivalent to 2.2 eV.
                      a. Predict the electrical properties of this solid on the basis of its band diagram.
                      That is, would you expect it to be a conductor, a semiconductor or an insulator?
                      Explain your answer.




     b. What would happen to the electrical properties of this compound if all of the electrons were
        removed only from the conduction band ? Why? Would you have to use a chemical oxidizing or
        reducing agent to accomplish this? Explain.




                                                                                                          29
Chem 124                                           Fall 2008                                          Dr. Neff



15. The following table shows the band gaps for a series of ionic compounds containing potassium. All
of these compounds adopt the NaCl structure, in which the bigger ion adopts a face centered cubic
structure and the other ion fills in the holes. (See page 454 in text for a picture of this structure). Explain
the observed trends in band gap for these materials based on any of the following that we talked about
today: MO theory; periodic properties; EN and % ionic character.


          Compoun                Band Gap, eV
             d
                KF                       11
                KCl                      8.5
                KBr                      7.5
                 KI                      5.8




16. Is visible light with wavelength 575 nm sufficient to move electrons in a metal? An insulator? A
semiconductor? List energy values (in eV) for this visible light quanta and E g values (in eV)
representative of each type of material to justify your answers.




17. 1. a) What wavelength of light will be sufficient to move electrons across the band gap in ZnS? Is
this visible light? GIVEN: E g for ZnS = 2.34 eV.




b) What voltage must you apply to move electrons across the band gap in a 1.25 cm thick piece of the
semiconductor ZnS?




c) What temperature in degrees K must you raise ZnS to in order to move electrons across the gap
thermally?

                                                                                                              30
Chem 124                                       Fall 2008                                        Dr. Neff




18. List three ways to affect the conductivity in metals and discuss how and why each affects
conductivity the way that it does.




19. a) Define p-type and n-type semiconductors, and list what elements would be appropriate to add to
Si to make each type of extrinsic semiconductor.




b) Describe how the band structure of Si is affected by addition of the above elements to make p- and n-
type semiconductors. Draw pictures of band structures to illustrate these changes.




20. In reference to the LED experiment we did and the discussion we had:

a) How does decreasing the temperature affect the conductivity of metals? Why?




b) How would one tune or change the band gap of a compound semiconductor like GaAs? Explain this
completely, including an explanation of why the band gap would change in the way it would change based
on your answer.



                                                                                                       31
Chem 124                                         Fall 2008                                         Dr. Neff

c) What effect does a change in temperature have on the intensity of light observed from LEDs? Why?




21. a) List two defining characteristics of superconductors as discussed in class.



b) What is the Meissner effect? How was this effect illustrated by the demo performed in class?




                    Chapter 9 Lattice Energy
a) Draw an energy level diagram that illustrates the Born Haber Cycle for CsBr. All the necessary
    enthalpy values are given below, in no particular order. Use this cycle to calculate the lattice energy
    for CsBr, and then compare it to the lattice energy for LiF (determined in class).

   Enthalpy of formation of CsBr           -405.9 kJ/mol

   1st Ionization energy of Cs             375.7 kJ/mol

   Atomization of Cs aka
      Enthalpy of Sublimation              76.1 kJ/mol

   Bond Energy of Br2 (l)                  193 kJ/mol

   Enthalpy of vaporization of Br2 (l)     30.9 kJ/mol

   Electron affinity of Br                 -325 kJ/mol




   b) Which of the following would you expect to have the highest magnitude of its lattice energy?
      Explain your choice clearly in terms of Coulomb’s Law.


                                                                                                          32
Chem 124                                        Fall 2008                                    Dr. Neff
              LiI           MgF2         RbBr          CaS




     Chapter 10 Lewis Structures, VSEPR
1. Certain trends in bond formation by elements can be identified. These are shown in the table below:
        Element         # of Bonds # of Lone Pairs The number of bonds an element tends to
         Carbon               4                0         form can be referred to as its valence,
        Nitrogen              3                1         and typically corresponds to how many
         Oxygen               2                2         electrons that element needs to complete
                                                         its octet. These rules will always hold true
        Fluorine              1                3         for hydrogen and fluorine, and generally
       Hydrogen               1                0         will hold true for the Period 2 non-metals.
                                                         However, they will not always work.
Some of the examples below illustrate this. Here, draw the best Lewis Structures for these covalent
species. None of these structures are cyclical. Make sure to take into account formal charge and draw
resonance structures when possible. When there are resonance structures that aren’t all the same, pick
the “best” one.

   SO3-2 Total # Valence Electrons:




  C2F4 (precursor to Teflon)
Total # Valence Electrons:




  COCl2 (phosgene – poison gas used in WW1)
Total # Valence Electrons:

                                                                                                     33
Chem 124                                      Fall 2008                                      Dr. Neff




  CH 3OH (methanol – drink it and go blind!)
Total # Valence Electrons:




  NO2+
Total # Valence Electrons:




  H3PO4
Total # Valence Electrons:




2. Consider the resonance structures shown below for the molecule phosgene, C l2CO. Based on all the
rules we discussed in class, choose the best Lewis structure (circle your choice), and briefly explain
why this is the best structure. Also tell me if this molecule would be polar or not.

                   O
                                            O                            O
                    C                       C                            C
             Cl          Cl          Cl          Cl               Cl          Cl

                                                                                                     34
Chem 124                                         Fall 2008                                     Dr. Neff




3. Calculate the enthalpy for the following reaction. Show all your work.

                                                        H

      H C         N     + 2H       H               H    C    N     H        H˚rxn = ?

                                                        H    H

        Bond            Energy in kJ/mol
          C-C                    347
          C-N                    305
          C=N                    615
          C N                    891
          C-H                    413
          N-H                    391
          N-N                    160
          N-O                    201
          N=N                    418


4. Fill in the tables below for each of the species shown. You must draw the Lewis Structure first. The
central atom does not necessarily have to follow the octet rule. Make sure to include formal charge and
possible resonance structures. Also remember that double and triple bonds count the same as single
bonds when determining geometries.

CF4




                                                                                                          35
Chem 124                                        Fall 2008                                        Dr. Neff
Total # of valence electrons:                    Total # of electron groups around the central
                                                 atom (bonded and non-bonded):
Lewis Structure, complete with formal charges
(show any possible resonance structures too!)
                                                 Electron Group Geometry:


                                                 # of bonded groups around the central atom
                                                 (connected to actual atoms):

VSEPR Sketch that shows 3-D shape of             Molecular Geometry:
molecule


                                                 Polar or not?




    -2
SO3
Total # of valence electrons:                    Total # of electron groups around the central
                                                 atom (bonded and non-bonded):
Lewis Structure, complete with formal charges
(show any possible resonance structures too!)
                                                 Electron Group Geometry:


                                                 # of bonded groups around the central atom
                                                 (connected to actual atoms):


VSEPR Sketch that shows 3-D shape of             Molecular Geometry:
molecule


                                                 Polar or not?




       +
ClF2




                                                                                                        36
Chem 124                                        Fall 2008                                        Dr. Neff
Total # of valence electrons:                    Total # of electron groups around the central
                                                 atom (bonded and non-bonded):
Lewis Structure, complete with formal charges
(show any possible resonance structures too!)
                                                 Electron Group Geometry:


                                                 # of bonded groups around the central atom
                                                 (connected to actual atoms):


                                                 Molecular Geometry:
VSEPR Sketch that shows 3-D shape of
molecule

                                                 Polar or not?




XeOF4
Total # of valence electrons:                    Total # of electron groups around the central
                                                 atom (bonded and non-bonded):
Lewis Structure, complete with formal charges
(show any possible resonance structures too!)
                                                 Electron Group Geometry:


                                                 # of bonded groups around the central atom
                                                 (connected to actual atoms):


                                                 Molecular Geometry:

VSEPR Sketch that shows 3-D shape of
molecule
                                                 Polar or not?




                                                                                                        37
Chem 124                             Fall 2008          Dr. Neff




            Chapter 15 Organic Chemistry

1. Name the molecules shown below:

                Structure                        Name
             CH2CH2CH3
         CH3CHCH2CH2CH2

                    CH3CHCH3


           CH2CH3           CH2CH3
      CH3CHCHCH2CHCH2CHCH3
             CH3     CH2CH2CH3




                                                               38
Chem 124                                    Fall 2008                                     Dr. Neff


                          CH3

           CH2   CHCH2 CHCH3


                     OH
      CH3CHCH2CHCH2CH2CH3
            CH2CH3

                 O

      CH3CH2CCH2CH2CHCH3
                           CHCH3
                           Br


            H            CH3
                 C   C
           H C           CH2 CH3
            3




  2. Draw the structure that corresponds to each of the names given below:



                                                                   4-ethyl-2-hexene




                                                                  4-bromo-2-pentyne




                                                                5,6 –dimethyl 1-octanol




                                                                                                 39
Chem 124                                        Fall 2008                                       Dr. Neff


                                                                       5-ethyl-2-heptanone




                                                                     5-methyl-8-ethyl-decanal




3. Write the condensed formulas for the following molecule (shown as a structural formula), and name the
molecule according to rules outlined in the handout and as illustrated in the text:

       H     H    H    CH3 H     H    H     H

 H     C     C    C    C    C    C    C     C    H

       H     H    H    H    H    H    CH3 H




4. Circle the longest continuous chain in each of the following, and name the molecules:

             CH2CH3             CH2CH3                 CH2CH2CH3
       CH3CHCHCH2CHCH2CHCH3                          CH3CHCH2CH2CH2

                 CH3    CH2CH2CH3                               CH3CHCH3


5. Name the following compounds according to the rules outlined in the notes & handout and as
illustrated in the text.
a.                                                    b.
                                                                 I
                 CH3
                                                             CH3CHCH2CH3
 CH2       CHCH2 CHCH3




                                                                       O
                       OH
c.     CH3CHCH2CHCH2CH2CH3                              d.   CH3CH2CCH2CH2CHCH3

             CH2CH3                                                              CHCH3
                                                                                  Br
                                                                                                       40
Chem 124                                     Fall 2008                             Dr. Neff




                             Cl
e.     CH3 CH2 CH2 CH2 CH2 CH

                             CH2
                             CH3




6. In each case below, the two molecules shown represent what type of isomerism?
              H3C           CH3                       H           CH3
                    C   C                                 C   C
              H3C           CH3                   H C             CH2 CH3
                                                   3




         CH3 CH CHCH2CH CH2                               CH3C      C CH2CH2
                                                                            CH3




             CH3CH2CH2CH2OH                        OH
                                              CH3CHCH2CH3



                                                  O
       CH2=CHCH2CH2OH                         CH3CCH2CH3



                                                                                          41
Chem 124                                         Fall 2008                                   Dr. Neff


7. Draw all the possible skeletal/structural isomers for C 7H16 (no rings).




8. Draw all the possible positional isomers for the molecule shown below.

                    CH3 CH2 C      C CH2 CH2 CH3




9. Draw one functional isomer and one positional isomer for 3-pentanone.




10. Use the following GC data to determine the identity of components in an unknown mixture: (each
small division on the x axis is ~ 6 seconds)




                                                                                                     42
Chem 124                                       Fall 2008                                      Dr. Neff




Your unknown mixture contains three components that give the following retention times. Write the
identity of each component in the corresponding space in the table.

         Component           Retention Time,                Identity of Component
                                seconds

              A                     96

              B                    113



              C                    174


11. Draw what the Gas Chromatograph should look like for a mixture containing equal amounts of the
   molecules decane, pentane, hexane and octane. I don’t expect you to know the EXACT retention
   times, I just want you to estimate RELATIVE retention times.




                                                                                                     43
Chem 124                                        Fall 2008                                        Dr. Neff
12. On the spectra below, label at least 2 major transmittance peaks with the corresponding organic
functional group. (See lab instructions online for vibrational frequency list –you must know some of these
frequencies, you WON’T get this table on the quiz or final!!!!)

Then decide which of the listed molecules would be best represented by the IR spectrum shown below,
and explain why you chose this molecule. (Draw the structures for all the possibilities, you should know
the frequencies for the most distinguishable bonds , like OH, C=O, CH3, CH2)


Propane              1-Propanol                  2-Propanone




                                                                                                           44

								
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