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Extra Problems for Exam II (OpenStax)

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  • These are homework exercises to accompany the Textmap created for "Chemistry" by OpenStax. Complementary General Chemistry question banks can be found for other Textmaps and can be accessed here. In addition to these publicly available questions, access to private problems bank for use in exams and homework is available to faculty only on an individual basis; please contact Delmar Larsen for an account with access permission.

    19.1: Occurrence, Preparation, and Properties of Transition Metals and Their Compounds


    Write the electron configurations for each of the following elements:

    1. Sc
    2. Ti
    3. Cr
    4. Fe
    5. Ru


    Sc: [Ar]4s23d1; Ti: [Ar]4s23d2; Cr: [Ar]4s13d5; Fe: [Ar]4s23d6; Ru: [Kr]5s24d6


    Write the electron configurations for each of the following elements and its ions:

    1. Ti
    2. Ti2+
    3. Ti3+
    4. Ti4+

    19.2: Coordination Chemistry of Transition Metals


    Indicate the coordination number for the central metal atom in each of the following coordination compounds:

    1. [Pt(H2O)2Br2]
    2. [Pt(NH3)(py)(Cl)(Br)] (py = pyridine, C5H5N)
    3. [Zn(NH3)2Cl2]
    4. [Zn(NH3)(py)(Cl)(Br)]
    5. [Ni(H2O)4Cl2]
    6. [Fe(en)2(CN)2]+ (en = ethylenediamine, C2H8N2)


    Give the coordination numbers and write the formulas for each of the following, including all isomers where appropriate:

    1. tetrahydroxozincate(II) ion (tetrahedral)
    2. hexacyanopalladate(IV) ion
    3. dichloroaurate ion (note that aurum is Latin for "gold")
    4. diaminedichloroplatinum(II)
    5. potassium diaminetetrachlorochromate(III)
    6. hexaaminecobalt(III) hexacyanochromate(III)
    7. dibromobis(ethylenediamine) cobalt(III) nitrate


    1. 4, [Zn(OH)4]2−;
    2. 6, [Pd(CN)6]2−;
    3. 2, [AuCl2];
    4. 4, [Pt(NH3)2Cl2];
    5. 6, K[Cr(NH3)2Cl4];
    6. 6, [Co(NH3)6][Cr(CN)6];
    7. 6, [Co(en)2Br2]NO3


    Give the coordination number for each metal ion in the following compounds:

    1. [Co(CO3)3]3− (note that CO32− is bidentate in this complex)
    2. [Cu(NH3)4]2+
    3. [Co(NH3)4Br2]2(SO4)3
    4. [Pt(NH3)4][PtCl4]
    5. [Cr(en)3](NO3)3
    6. [Pd(NH3)2Br2] (square planar)
    7. K3[Cu(Cl)5]
    8. [Zn(NH3)2Cl2]


    Sketch the structures of the following complexes. Indicate any cis, trans, and optical isomers.

    1. [Pt(H2O)2Br2] (square planar)
    2. [Pt(NH3)(py)(Cl)(Br)] (square planar, py = pyridine, C5H5N)
    3. [Zn(NH3)3Cl]+ (tetrahedral)
    4. [Pt(NH3)3Cl]+ (square planar)
    5. [Ni(H2O)4Cl2]
    6. [Co(C2O4)2Cl2]3− (note that \(\ce{C2O4^2-}\) is the bidentate oxalate ion, \(\ce{−O2CCO2-}\))


    a. [Pt(H2O)2Br2]:

    b. [Pt(NH3)(py)(Cl)(Br)]:

    c. [Zn(NH3)3Cl]+ :

    d. [Pt(NH3)3Cl]+ :

    e. [Ni(H2O)4Cl2]:

    f. [Co(C2O4)2Cl2]3−:


    Draw diagrams for any cis, trans, and optical isomers that could exist for the following (en is ethylenediamine):

    1. [Co(en)2(NO2)Cl]+
    2. [Co(en)2Cl2]+
    3. [Pt(NH3)2Cl4]
    4. [Cr(en)3]3+
    5. [Pt(NH3)2Cl2]


    Name each of the compounds or ions given in Exercise Q19.2.3, including the oxidation state of the metal.


    1. tricarbonatocobaltate(III) ion;
    2. tetraaminecopper(II) ion;
    3. tetraaminedibromocobalt(III) sulfate;
    4. tetraamineplatinum(II) tetrachloroplatinate(II);
    5. tris-(ethylenediamine)chromium(III) nitrate;
    6. diaminedibromopalladium(II);
    7. potassium pentachlorocuprate(II);
    8. diaminedichlorozinc(II)


    Name each of the compounds or ions given in Exercise Q19.2.5.


    Specify whether the following complexes have isomers.

    1. tetrahedral [Ni(CO)2(Cl)2]
    2. trigonal bipyramidal [Mn(CO)4NO]
    3. [Pt(en)2Cl2]Cl2


    none; none; The two Cl ligands can be cis or trans. When they are cis, there will also be an optical isomer.


    Predict whether the carbonate ligand \(\ce{CO3^2-}\) will coordinate to a metal center as a monodentate, bidentate, or tridentate ligand.


    Draw the geometric, linkage, and ionization isomers for [CoCl5CN][CN].

    19.3: Spectroscopic and Magnetic Properties of Coordination Compounds


    Determine the number of unpaired electrons expected for [Fe(NO2)6]3−and for [FeF6]3− in terms of crystal field theory.


    Draw the crystal field diagrams for [Fe(NO2)6]4− and [FeF6]3−. State whether each complex is high spin or low spin, paramagnetic or diamagnetic, and compare Δoct to P for each complex.



    Give the oxidation state of the metal, number of d electrons, and the number of unpaired electrons predicted for [Co(NH3)6]Cl3.


    The solid anhydrous solid CoCl2 is blue in color. Because it readily absorbs water from the air, it is used as a humidity indicator to monitor if equipment (such as a cell phone) has been exposed to excessive levels of moisture. Predict what product is formed by this reaction, and how many unpaired electrons this complex will have.


    [Co(H2O)6]Cl2 with three unpaired electrons.


    Is it possible for a complex of a metal in the transition series to have six unpaired electrons? Explain.


    How many unpaired electrons are present in each of the following?

    1. [CoF6]3− (high spin)
    2. [Mn(CN)6]3− (low spin)
    3. [Mn(CN)6]4− (low spin)
    4. [MnCl6]4− (high spin)
    5. [RhCl6]3− (low spin)


    4; 2; 1; 5; 0


    Explain how the diphosphate ion, [O3P−O−PO3]4−, can function as a water softener that prevents the precipitation of Fe2+ as an insoluble iron salt.


    For complexes of the same metal ion with no change in oxidation number, the stability increases as the number of electrons in the t2g orbitals increases. Which complex in each of the following pairs of complexes is more stable?

    1. [Fe(H2O)6]2+ or [Fe(CN)6]4−
    2. [Co(NH3)6]3+ or [CoF6]3−
    3. [Mn(CN)6]4− or [MnCl6]4−


    [Fe(CN)6]4−; [Co(NH3)6]3+; [Mn(CN)6]4−


    Trimethylphosphine, P(CH3)3, can act as a ligand by donating the lone pair of electrons on the phosphorus atom. If trimethylphosphine is added to a solution of nickel(II) chloride in acetone, a blue compound that has a molecular mass of approximately 270 g and contains 21.5% Ni, 26.0% Cl, and 52.5% P(CH3)3 can be isolated. This blue compound does not have any isomeric forms. What are the geometry and molecular formula of the blue compound?


    Would you expect the complex [Co(en)3]Cl3 to have any unpaired electrons? Any isomers?


    The complex does not have any unpaired electrons. The complex does not have any geometric isomers, but the mirror image is nonsuperimposable, so it has an optical isomer.


    Would you expect the Mg3[Cr(CN)6]2 to be diamagnetic or paramagnetic? Explain your reasoning.


    Would you expect salts of the gold ion, Au+, to be colored? Explain.


    No. Au+ has a complete 5d sublevel.


    [CuCl4]2− is green. [Cu(H2O)6]2+is blue. Which absorbs higher-energy photons? Which is predicted to have a larger crystal field splitting?