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					      Candidate’s Student Identification Number:      .......................
      Candidate’s Course Code                         KRA..............



                                                                                    Pages:   20
                                                                                Questions:   18
                                                                                Section A:    3
                                                                                Section B:    6
                                                                                Section C:    3
                                                                                Section D:    6




                             UNIVERSITY OF TASMANIA



                 EXAMINATIONS FOR DEGREES AND DIPLOMAS


                                 October/November 2004




                         KRA110, KRA115, KRA120, KRA160
                                   Chemistry 1


                                        PAPER 2


         Examiners: Dr Vicki Tolhurst, Dr Greg Dicinoski, Dr Brian Yates



                             Time allowed: THREE (3) hours



    Answer ALL EIGHTEEN (18) questions. All questions are of equal mark value.
Molecular models and any type of hand-held battery operated calculator may be taken into the
                                      examination.
Chemistry 1 Paper 2 2004                                                                       2

Section A                        Coordination Chemistry                   Dr Vicki Tolhurst


Question 1
a   Write electron configurations for each of the following:


     i.     Zn2+

     ii.    V2+


     iii.   Fe3+

                                                                                      [3 marks]
b    Determine the oxidation and coordination numbers for the transition metal ion in the
     following complexes and give their names.

 K2[FeBr4(en)]                   Oxidation number:




                                 Coordination number:
                                 Name:


 [VBrCl(en)2]                    Oxidation number:




                                 Coordination number:
                                 Name:


 [Mn(en)2(NH3)(OH2)](NO3)2       Oxidation number:



                                 Coordination number:
                                 Name:


                                                                                     [9 marks]




                                                                                         /12
Chemistry 1 Paper 2 2004                                                                      3

Section A                         Coordination Chemistry                    Dr Vicki Tolhurst


Question 2
a   i.     What is the definition of coordination (constitution) isomers?




     ii.    Write the formula for each of the coordination isomers of CoBrCl2(NH3)4 (assume
            coordination number of Co = 6 only).




                                                                           [3 marks]
b    Which of the following ligands cannot form linkage isomers when contained in a
     complex: NO2-, en, SCN-? Explain why using diagrams.




                                                                                 [3 marks]
c    Draw the three-dimensional structures for all possible isomers of [Cr(NO2)2(H2O)4].




                                                                                    [6 marks]



                                                                                        /12
Chemistry 1 Paper 2 2004                                                                          4

Section A                         Coordination Chemistry                    Dr Vicki Tolhurst


Question 3
a   Explain the difference between a high spin and a low spin complex in terms of ∆o. Will a
     high spin complex absorb light at a larger or smaller wavelength than a low spin complex?




                                                                                     [3 marks]
b    Explain the difference between a strong field ligand and a weak field ligand in terms of
     their effect on ∆o. Will a strong field ligand form a high or low spin complex?




                                                                                      [3 marks]
c    The complex [Co(H2O)6]2+ is high spin but [Co(CN)6]4- is low spin although the metal in
     each complex has the same oxidation number.


     i.     Determine the oxidation number of the metal and its electronic configuration.




     ii.    Draw the energy level splitting diagram for the above high spin and low spin cobalt
            ions, indicating which diagram belongs to each complex.




     iii.   Based on your results give the number of unpaired electrons for each complex.


                                                                                      [6 marks]




                                                                                            /12
Chemistry 1 Paper 2 2004                                                                        5

Section B                             Thermodynamics                       Dr Greg Dicinoski


Question 1
a   On what law is the first law of thermodynamics based?




                                                                                      [1 marks]
b    Explain the sign conventions used in the equation, ∆U = q + w.




                                                                                 [2 marks]
c    The work done to compress a gas is 74 J. As a result, 26 J of heat is given off to the
     surroundings. Calculate the change in the internal energy of the gas.




                                                                                  [3 marks]
                             2                                               2
d    A quantity of 2.00x10 mL of 0.862 M HCl is mixed with 2.00x10 mL of 0.431 M
     Ba(OH)2 in a constant pressure calorimeter of negligible heat capacity. The initial
     temperature of the HCl and Ba(OH)2 solutions are both the same at 20.48 oC. For the
     process, H+(aq) + OH-(aq) → H2O(l), the heat of neutralisation is -56.2 kJ/mol.
     i.     Calculate the moles of H+ and OH- present in the solution.




     ii.    Determine q for this process.




     iii.   Calculate the final temperature of the solution given the specific heat capacity and
            mass of the final solution is 4.18 J/g/oC and 400 g respectively.




                                                                                      [6 marks]



                                                                                          /12
Chemistry 1 Paper 2 2004                                                                    6

Section B                           Thermodynamics                      Dr Greg Dicinoski


Question 2
a   What is meant by the Standard Enthalpy of Reaction? Provide an equation by which this
    quantity can be calculated.




                                                                                  [3 marks]
b    From the following heats of combustion,
             1. 2 CH3OH(l) + 3 O2(g) → 2 CO2(g) + 4 H2O(l), ∆H = -1452.8 kJ
             2. C(s) + O2(g) → CO2(g), ∆H = -393.5 kJ
             3. H2(g) + _ O2(g) → H2O(l), ∆H = -285.8 kJ
     calculate the enthalpy of formation of methanol (CH3OH) from its elements:
                              C(s) + 2 H2(g) + _ O2(g) → CH3OH(l).




                                                                                [6 marks]
c    The ∆H f values for the two allotropes of oxygen, O 2 and O 3 are 0 and 142.2 kJ/mol,
             o


     respectively at 25 oC. Which is the more stable form of oxygen at this temperature?
     Explain your answer.




                                                                                  [3 marks]




                                                                                      /12
Chemistry 1 Paper 2 2004                                                                          7

Section B                              Thermodynamics                        Dr Greg Dicinoski


Question 3
a   How does the entropy of a system change for each of the following processes? (Increase,
    Decrease, No Change).
    i.      A solid melts                        ________________
    ii.     A liquid boils                       ________________
    iii.    A vapour condenses to a solid ________________
    iv.     Sugar dissolves in water             ________________
                                                                                 [2 marks]
b   The element gallium, Ga, freezes at 29.8 C, and its enthalpy of fusion is ∆Hfus = 5.59
                                             o


     kJ/mol.

     i.     When Ga(l) freezes to Ga(s) at 29.8 oC, is ∆S positive or negative?



     ii.    Calculate the value of ∆S for the freezing of 45.0 g of Ga(l) at 29.8 oC.




                                                                                        [5 marks]
c    i.     What is the change in entropy, ∆So, for the reaction:
            2 Al(s) + 3 ZnO(s) → Al2O3(s) + 3 Zn(s).


                                Compound         Sof (J/K/mol)
                                Al(s)            28.3
                                ZnO(s)           43.9
                                Al2O3(s)         50.99
                                Zn(s)            41.6




     ii.       Does the entropy of the chemical system increase or decrease as you expect?
               Explain.

                                                                                        [5 marks]



                                                                                            /12
Chemistry 1 Paper 2 2004                                                                           8

Section B                             Thermodynamics                        Dr Greg Dicinoski


Question 4
a   Define free energy, and give its units.




                                                                                  [3 marks]
b    Carbon monoxide (CO) and nitric oxide (NO) are polluting gases contained in automobile
     exhaust. Under suitable conditions, these gases can be made to react with each other to
     form nitrogen gas (N2) and the less harmful carbon dioxide (CO2).

     i.     Write the balanced equilibrium equation that corresponds to this reaction.




                                                                                   [2 marks]
     ii.    If the value of ∆Go for this equilibrium is -119.8 kJ/mol, calculate K p for this
            reaction at 25 oC.




                                                                    [3 marks]
     iii.   What is the value of ∆G when PN2 = 0.80 atm, PCO2 = 3.0x10-4 atm,
            PCO = 5.0x10-5 atm, and PNO = 5.0x10-7 atm?




                                                                                         [4 marks]




                                                                                             /12
Chemistry 1 Paper 2 2004                                                                               9

Section B                                 Thermodynamics                         Dr Greg Dicinoski


Question 5
a   The boiling point and freezing point of sulphur dioxide (SO2) are -10 oC and -72.7 oC (at
    1 atm) respectively. The triple point is -75.5 oC and 1.65x10-3 atm, and its critical point is
    at 157 oC and 78 atm. On the basis of this information, draw a rough sketch of the phase
    diagram of SO2.




                                                                                            [5 marks]
b     This question relates to some physical properties of carbon
      dioxide, the phase diagram of which is provided.


      i.       Describe what happens when CO2 at 3 atm is heated
               from -80 oC to +20 oC at constant pressure.




      ii.      Draw and label the heating curve for this process.




                                                                                              [4 marks]
c.         A glass can be filled slightly above the rim with water. Explain, with the aid of a diagram,
           why the water does not overflow.



                                                                                            [3 marks]




                                                                                                 /12
Chemistry 1 Paper 2 2004                                                                    10

Section B                             Thermodynamics                       Dr Greg Dicinoski


Question 6
a   What are colligative properties? Give an example of a colligative property.




                                                                                      [2 marks]
b    A solution containing 0.8330 g of a polymer of unknown structure in 170.0 mL of an
     organic solvent was found to have an osmotic pressure of 5.20 mm of Hg at 25 oC (Hint:
     is this the correct unit of pressure?). Determine the molar mass of the polymer.




                                                                                     [6 marks]
c    Acetic acid is weak acid that ionises in solution as follows:
     CH3COOH                CH3COO- + H+.
     If the freezing point of a 0.106 m (mol/kg) CH3COOH aqueous solution is -0.203 oC,
     calculate the percent of the acid that has undergone ionisation. The freezing point
     depression constant for water is 1.86 oC/kg/mol. (Hint: what is the freezing point of the
     pure solvent?).




                                                                                     [4 marks]



                                                                                         /12
Chemistry 1 Paper 2 2004                                                                       11



Section C                            Separation Science                     Dr Greg Dicinoski


Question 1
a   List 3 different separation techniques used in chemistry.




                                                                                      [3 marks]
b    Describe the process of solvent extraction using relevant equations and diagrams.




                                                                                         [5 marks]
c    A solute, S, has a distribution ratio between water and benzene of 1.5. Calculate the % S in
     both the aqueous (%q) and organic (%p) phases if a 50.0 mL aqueous sample of S is
     extracted with 50.0 mL of benzene.




                                                                                       [4 marks]



                                                                                            /12
Chemistry 1 Paper 2 2004                                                                  12



Section C                           Separation Science                   Dr Greg Dicinoski


Question 2
a   What is the minimum distribution coefficient that permits removal of 99 % of a solute
    from 50.0 mL of water with five 10.0 mL extractions with toluene?




                                                                                   [4 marks]
b    i.     The K p for the extraction of butylamine (a weak base) from water with toluene is
            5.0. If 35.0 mL of a 0.025 M aqueous solution of butylamine is extracted with 75
            mL of toluene, what will be the concentration of butylamine remaining in the
            aqueous phase at pH 10.0, given the Kb for butylamine is 8.0x10-4?




                                                                                   [8 marks]



                                                                                       /12
Chemistry 1 Paper 2 2004                                                                         13



Section C                                Separation Science                      Dr Greg Dicinoski


Question 3
a   The relevant equilibria for extracting iodine from an aqueous solution containing
    thiocyanate (SCN-) into an organic phase are shown in the following diagram.
             I2

                   Kp                             Organic
                                                  Aqueous
                                    2 I(SCN)2-
                               - ←→Kf
                I2 + 2 SCN
     i.       Will the extraction efficiency for I2 be greater for higher or lower concentrations of
              SCN-? Explain your answer in terms of equilibrium chemistry.




                                                                                          [2 marks]
     ii.      Derive an expression for the distribution ratio, D, for this extraction.




           +
           =
           p K[SCN]
           1
           D
           K
           −
           2
           f                                                                              [8 marks]

b    If                        , Kp = 25, Kf = 1200, and [L-] = 0.050 M, calculate the distribution

     ratio, D, for the extraction of I2 from the aqueous to organic phase.




                                                                                          [2 marks]



                                                                                              /12
Chemistry 1 Paper 2 2004                                                                       14



Section D                              Organic Structures & Reactions          Dr Brian Yates

Question 1
a   Give the systematic name of this compound:
                                                                                    O

                                                                  CH3   CH   CH 2    C     CH 3

                                                                        Br

                                                                                         [4 marks]
b     Show the product of the following oxidation reaction.

                     O                 Tollens' reagent
                     C
      CH3CH2              H



                                                                                  [4 marks]
c     Sketch the mechanism (using curly arrows) for the acid catalysed nucleophilic addition
      reaction of water with the aldehyde ethanal, CH3CHO. (Hint: The nucleophilic addition
      occurs in the second step.)


       O                          H
       C             +            O+                                                + H 2O
CH3             H         H             H




                OH
                                                   H 2O
                              +       H3O+
      CH3
                     OH
            H

                                                                                         [4 marks]




                                                                                             /12
Chemistry 1 Paper 2 2004                                                                       15



Section D                      Organic Structures & Reactions                  Dr Brian Yates

Question 2
a   Draw the structure of ethyl 3-nitrobenzoate.




                                                                                        [4 marks]
b    i      Write down the reactant (an alcohol) in the following reaction.




                                                                              CH3       O
                                           CrCO3
                                                               CH3 CH2 CH           C
                                       H2O, H2SO4
                                                                                        OH
               an alcohol

                                                                                        [2 marks]
     ii     Is this reaction a reduction or an oxidation?



                                                                                    [2 marks]
c    Sketch the mechanism (using curly arrows) for the nucleophilic acyl substitution reaction
     of the acid chloride CH3COCl with H2O.




                                                                                             /12
Chemistry 1 Paper 2 2004                                 16



             O
                                H 2O
             C
     CH3         Cl




                                           – Cl–



                           O
                                       ?
                           C
                  CH3          OH


                                                   [4 marks]




                                                       /12
Chemistry 1 Paper 2 2004                                                                    17



Section D                    Organic Structures & Reactions                   Dr Brian Yates

Question 3
a   Give the systematic name of this compound:
                                                                                 H
                                                     CH3 CH2 CH         CH2 N

                                                                 CH3             CH2 CH3



                                                                                      [4 marks]
b    Write down the reagents used to carry out the following synthesis of an amine.

     CH 3CH 2Br                       CH3CH 2NH 3+                      CH 3CH2NH 2

                                          + Br–




                                                                                  [4 marks]
c    Sketch the mechanism (using curly arrows) for the reaction of an amine CH 3NH 2 with an
     acid halide CH3COCl.



                             O

     CH 3NH 2     +          C
                      CH 3       Cl



                                                                   – Cl–



                  O
                                      ?
                  C
          CH 3        NHCH3


                                                                                      [4 marks]



                                                                                          /12
Chemistry 1 Paper 2 2004                                                                        18



Section D                   Biologically Important Compounds                     Dr Brian Yates

Question 4
a   i      Is the following fatty acid saturated or unsaturated?
                       CH 3CH 2CH=CHCH 2CH=CHCH 2CH 2COOH


                                                                                        [2 marks]
      ii    Show what happens to the fatty acid in part (i) when it is hydrogenated:
                           H 2 / Pt
               atty acid


                                                                                    [2 marks]
      iii   Will hydrogenation raise or lower the melting point of the fatty acid in part (i)?
            Explain your answer.




                                                                                          [4 marks]
b     i     Cholesterol belongs to a particular class of lipids. What is this class, and how can it
            be distinguished from the complex lipids?



                                     CH3


                      CH3




      HO
                                      cholesterol


                                                                                         [2 marks]
      ii    What part does cholesterol play in the biosynthesis of all the natural steroids?
                                                                                         [2 marks]




                                                                                             /12
Chemistry 1 Paper 2 2004                                                                   19



Section D                  Biologically Important Compounds                    Dr Brian Yates

Question 5
a   i      Explain the relationship between mono-, di- and poly-saccharides.




                                                                                     [2 marks]
     ii     Name one example each of a disaccharide and a polysaccharide.


                      a disaccharide:
                      a polysaccharide:


                                                                            [2 marks]
b    Write down the product of the reaction of β-D-glucopyranose with CH3I to form a
     pentamethyl ether. What other reagent is required?
                                                                                     [4 marks]
                CH2OH
                           O                     CH3I
     HO
       HO                           OH             ?


               β-D-Glucopyranose



c    Explain what is meant by an α-glycoside bond.




                                                                                     [4 marks]




                                                                                         /12
Chemistry 1 Paper 2 2004                                                              20



Section D                  Biologically Important Compounds              Dr Brian Yates

Question 6
a   Explain, with an example, what is meant by the "peptide bond".




                                                                                [4 marks]
b    Describe briefly the chemical reactions involved in the synthesis of peptides in the
     laboratory.




                                                                               [8 marks]



                                                                                    /12
Chemistry 1 Paper 2 2004                                                     21




         Section        A             B             C              D
                   Coord. Chem.   Thermodyn.   Sep.Science   Organic Chem.


Q1 /12




Q2 /12




Q3 /12




Q4 /12




Q5 /12




Q6 /12




Totals                     /36           /72           /36            /72




Grand Total                /216

				
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