# Extra Problems for Exam II

Solutions are found here.

D1.
Which of the following is NOT true for the Group 1A elements?
(a) Most of them are soft, silvery corrosive metals.
(b) Their atomic radii increases with increasing molecular weight.
(c) They are named the alkaline earth metals.
(d) They are excellent conductors of heat and electricity.
(e) They exhibit a +1 oxidation state in compounds.
D2.
Which element group is the most reactive of all the metallic elements?
(a) alkali metals
(b) alkaline earth metals
(c) coinage metals
(d) transition metals
(e) Group 2B metals
D3.
In a surprisingly large number of their properties beryllium resembles aluminum, and boron resembles silicon. Such a relationship is called:
(a) amphoterism
(b) an allotropic relationship
(c) a diagonal relationship
(d) the periodic law
(e) an isoelectronic series
D4.
Which of the following properties of the alkaline earth metals decreases with increasing atomic weight?
(b) ionization energy
(d) activity
(e) atomic number
D5.
Of the following oxides, the most basic is:
(a) MgO.
(b) Na2O.
(c) P2O3.
(d) BeO.
(e) SO2.
D6.
A 300 g sample of CaCO3 was heated until 10.0 L of CO2 was collected at 50.0oC and 742 torr. What percentage of the CaCO3 had decomposed?
(a) 6.84%
(b) 9.10%
(c) 12.3%
(d) 15.8%
(e) 20.6%
D7.
What mass of lithium nitride could be formed from 104 g of lithium and excess nitrogen gas?
(a) 35 g
(b) 60 g
(c) 105 g
(d) 140 g
(e) 174 g
D8.
The most abundant metal in the earth's crust is:
(a) Cu
(b) Fe
(c) Na
(d) Al
(e) Ca
D9.
Which element has the electron configuration [Ar] 3d7 4s2?
(a) Fe
(b) Co
(c) Cr
(d) Ti
(e) Zn
D10.
What is the electron configuration of Mn3+ ion?
(a) [Ar] 4s2 3d10
(b) [Ar] 4s2 3d2
(c) [Ar] 3d5
(d) [Ar] 3d4
(e) [Ar] 4d1 3d3
D11.
The nitrate of which of the following cations would exhibit paramagnetism to the GREATEST extent?
(a) Co3+
(b) Cr3+
(c) Fe3+
(d) Mn3+
(e) V3+
E1.
Some element groups of the periodic table are more likely to contain elements that are gases than other groups. Which of the following groups contains the greatest number of gaseous elements?
(a) IA
(b) IIA
(c) IVA
(d) VIA
(e) VIII (or 0)
E2.
Which of the following is NOT true for the halogens?
(a) They are nonmetals.
(b) They show the -1 oxidation number in most of their compounds.
(c) The electronic configuration of their outermost electrons is ns2 np6.
(d) Their compounds with metals are generally ionic in nature.
(e) Elemental halogens exist as diatomic molecules.
E3.
Which of the following substances is the strongest reducing agent?
(a) Cl2
(b) Cl-
(c) Br2
(d) Br-
(e) I2
E4.
Chlorine gas is prepared commercially by:
(a) electrolysis of carbon tetrachloride.
(b) oxidation of chloride ion with F2(g).
(c) electrolysis of NaCl(aq).
(d) oxidation of chloride ion with Br2(aq).
(e) electrolysis of AlCl3(aq).
E5.
Which one of the following does not correctly describe one or all of the hydrogen halides, HX?
(a) Their aqueous solutions are acidic.
(b) HF has the lowest of the H-X bond energies.
(c) HI is the largest.
(d) HCl has the lowest boiling point.
(e) HF exhibits hydrogen bonding.
E6.
Of the oxyacids listed below, which one possesses the greatest acid strength in water?
(a) HClO4
(b) H2CO3
(c) H3BO3
(d) HClO
(e) HBrO
E7. (not for chem 2c)
Draw the correct Lewis formula for chlorous acid. The structure contains ___ single bonds, ___ double bonds and ___ lone pairs of electrons.
(a) 2, 1, 5
(b) 3, 0, 7
(c) 1, 2, 4
(d) 2, 1, 5
(e) none of these
E8. (not for chem 2C)
Which of the following has a pyramidal structure (molecular geometry)?
(a) CBr4
(b) PF3
(c) BF3
(d) OF2
(e) BrCl
E9.
Which statement about the Group VIA elements is false?
(a) All have an outer electronic configuration of ns2 np4.
(b) The electronegativity of Group VIA elements decreases as one goes down the group.
(c) Most are found in sulfide deposits.
(d) Oxygen has the highest boiling point and melting point.
(e) Polonium has the smallest first ionization energy.
E10.
Which statement about the Group VIA hydrides is false?
(a) H2S, H2Se and H2Te are all gases at room temperature and atmospheric pressure.
(b) All are colorless.
(c) All except H2O are toxic.
(d) H2Po has the lowest boiling point.
(e) All are covalent compounds.
E11. (not for chem 2C)
Which acid listed on the right cannot be obtained by adding water to the substance on the left?
(a) H2S2O7 - sulfuric acid
(b) SeO2 - selenous acid
(c) SO3 - sulfuric acid
(d) SO2 - sulfurous acid
(e) TeO2 - tellurous acid
E12.
Which of the following statements about sulfuric acid is false?
(a) It is a strong acid.
(b) One mole of sulfuric acid reacts completely with two moles of potassium hydroxide.
(c) The sulfur atom is sp2 hybridized.
(d) It is often present in acid rain.
(e) During the dilution of sulfuric acid, the correct method is to add sulfuric acid to water.
E13.
What maximum mass of sulfuric acid can be produced from the sulfur contained in 100 kilograms of iron pyrite that is 75.0% FeS2?
(a) 84.4 kg
(b) 123 kg
(c) 136 kg
(d) 144 kg
(e) 168 kg
E14.
In which one of the following is the oxidation state of nitrogen given incorrectly?
(a) N2O3, +3
(b) N2H4, +2
(c) HNO3, +5
(d) NaNO2, +3
(e) H2N2O2, +1
E15.
Which of the following does not correctly describe ammonia?
(a) pyramidal molecule
(b) polar molecule
(c) extremely soluble in water
(d) forms basic aqueous solutions
(e) none of these
E16.
Which compound gives photochemical smog a brownish color?
(a) NO
(b) HNO2
(c) NO2
(d) N2O4
(e) N2O3
E17. (not for chem 2C)
What is the major mineral present in phosphate rock?
(a) Ca3(PO4)2
(b) Na2HPO4
(c) Ca10(PO4)6F2
(d) NaH2PO4
(e) Ca10(PO4)6(OH)2
F1.
The ______ sphere is enclosed in brackets in formulas for complex species, and it includes the central metal ion plus the coordinated groups.
(a) ligand
(b) donor
(c) oxidation
(d) coordination
(e) chelating
F2.
In coordination chemistry, the donor atom of a ligand is
(a) a Lewis acid.
(b) the counter ion
(c) the central metal atom.
(d) the atom in the ligand that shares an electron pair with the metal.
(e) the atom in the ligand that accepts a share in an electron pair from the metal.
F3.
Consider the coordination compound, Na2[Pt(CN)4]. The Lewis acid is
(a) [Pt(CN)4]2-
(b) Na+
(c) Pt
(d) Pt2+
(e) CN-
F4.
Consider the coordination compound, K2[Cu(CN)4]. A coordinate covalent bond exists between
(a) K+ and CN-
(b) Cu2+ and CN-
(c) K+ and [Cu(CN)4]2-
(d) C and N in CN-
(e) K+ and Cu2+
F5.
Given the list of ligands and their corresponding names, choose the pair that disagree.
 LIGAND NAME (a) OH- hydroxo (b) CN- cyanide (c) Cl- chloro (d) H2O aqua (e) NH3 ammine
F6.
Select the correct IUPAC name for: [FeF4(OH2)2]-
(a) diaquatetrafluoroiron(III) ion
(b) diaquatetrafluoroferrate(III) ion
(c) diaquatetrafluoroiron(I) ion
(d) diaquatetrafluoroferrate(I) ion
(e) none of these
F7.
Select the correct IUPAC name for: [Co(NH3)6]2+
(a) hexammoniacobaltate(II) ion
(b) hexaamminecobaltate(II) ion
(c) hexammoniacobalt(II) ion
(d) hexaamminecobalt(II) ion
(e) hexammoniacobalt ion
F8.
Which name-formula combination is NOT correct?
 FORMULA NAME (a) [Co(NH3)4(OH2)I]SO4 tetraammineaquaiodocobalt(III) sulfate (b) K[Cr(NH3)2Cl4] potassium diamminetetrachlorochromate(III) (c) [Mn(CN)5]2- pentacyanomanganate(II) ion (d) [Ni(CO)4] tetracarbonylnickel(0) (e) Ca[PtCl4] calcium tetrachloroplatinate(II)
F9.
What is the oxidation number of the central metal atom in the coordination compound [Pt(NH3)3Cl]Cl?
(a) -1
(b) 0
(c) +1
(d) +2
(e) +3
F10. (not for chem 2C)
(Valance Bond Theory) Magnetic measurements indicate that [Co(OH2)6]2+ has 3 unpaired electrons. Therefore, the hybridization of the metal's orbitals in [Co(OH2)6]2+ is:
(a) sp3
(b) sp2d
(c) dsp2
(d) sp3d2
(e) d2sp3
F11.
Which one of the following complexes can exhibit geometrical isomerism?
 (a) [Pt(NH3)2Cl2] (square planar) (b) [Zn(NH3)2Cl2] (tetrahedral) (c) [Cu(NH3)4]2+ (square planar) (d) [Co(NH3)5Cl]2+ (octahedral) (e) [Cu(CN)2]- (linear)
F12.
A molecule that cannot be superimposed on its mirror image is said to exhibit which of the following?
(a) geometrical isomerism
(b) optical isomerism
(d) reactive isomerism
(e) coordination isomerism
F13.
In which one of the following species does the transition metal ion have d3 electronic configuration?
(a) [Cr(NH3)6]3+
(b) [Co(OH2)6]2+
(c) [CoF6]3-
(d) [Fe(CN)6]3-
(e) [Ni(OH2)6]2+
F14. (not for chem 2C)
(Valence Bond Theory) The coordination complex, [Cu(OH2)6]2+ has one unpaired electron. Which of the following statements are true?
(1) The complex is octahedral.
(2) The complex is an outer orbital complex.
(3) The complex is d2sp3 hybridized.
(4) The complex is diamagnetic.
(5) The coordination number is 6.
(a) 1, 4
(b) 1, 2, 5
(c) 2, 3, 5
(d) 2, 3
(e) 4, 5
F15.
(Crystal Field Theory) Which one of the following statements is FALSE?
(a) In an octahedral crystal field, the d electrons on a metal ion occupy the eg set of orbitals before they occupy the t2g set of orbitals.
(b) Diamagnetic metal ions cannot have an odd number of electrons.
(c) Low spin complexes can be paramagnetic.
(d) In high spin octahedral complexes, oct is less than the electron pairing energy, and is relatively very small.
(e) Low spin complexes contain strong field ligands.
F16.
(Crystal Field Theory) When the valence d orbitals of the central metal ion are split in energy in an octahedral ligand field, which orbitals are raised least in energy?
(a) dxy and dx2-y2
(b) dxy, dxz and dyz
(c) dxz and dyz
(d) dxz, dyz and dz2
(e) dx2-y2 and dz2
F17.
(Crystal Field Theory) How many unpaired electrons are there in a strong field iron(II) octahedral complex?
(a) 0
(b) 1
(c) 2
(d) 4
(e) 6
F18.
(Crystal Field Theory) Consider the complex ion [Mn(OH2)6]2+ with 5 unpaired electrons. Which response includes all the following statements that are true, and no false statements?
I. It is diamagnetic.
II. It is a low spin complex.
III. The metal ion is a d5 ion.
IV. The ligands are weak field ligands.
V. It is octahedral.
(a) I, II
(b) III, IV, V
(c) I, IV
(d) II, V
(e) III, IV
F19.
(Crystal Field Theory) Consider the violet-colored compound, [Cr(OH2)6]Cl3 and the yellow compound, [Cr(NH3)6]Cl3. Which of the following statements is false?

(a) Both chromium metal ions are paramagnetic with 3 unpaired electrons.
(b) oct for [Cr(NH3)6]3+ is calculated directly from the energy of yellow light.
(c) oct for [Cr(OH2)6]3+ is less than oct for [Cr(NH3)6]3+.
(d) A solution of [Cr(OH2)6]Cl3 transmits light with an approximate wavelength range of 4000 - 4200 angstroms.
(e) The two complexes absorb their complementary colors.
F20.
(Crystal Field Theory) Strong field ligands such as CN-:
(a) usually produce high spin complexes and small crystal field splittings.
(b) usually produce low spin complexes and small crystal field splittings.
(c) usually produce low spin complexes and high crystal field splittings.
(d) usually produce high spin complexes and high crystal field splittings.
(e) cannot form low spin complexes.

## G1.

Werner also studied the electrical conductance of aqueous solutions containing a series of platinum(IV) complexes having the general formula Pt(NH3)xCl4, where x is an integer that varied from 2 to 6. His results can be summarized as:

 Formula of Complex Number of ions produced upon complete dissociation Pt(NH3)6Cl4 5 Pt(NH3)5Cl4 4 Pt(NH3)4Cl4 3 Pt(NH3)3Cl4 2 Pt(NH3)2Cl4 0

Assuming that Pt(IV) forms octahedral complexes, (a) write the formulas for the five compounds based on the dissociation results, (b) draw three-dimensional sketches of the complexes, (include isomers that are possible), and (c) name each compound.

## G2 (ignore for chem 2C)

Crystal Field Theory fails in explaining why a neutral ligand such as CO can cause a very large crystal field splitting. Use Molecular Orbital Theory to explain why the CO ligand leads to a higher crystal field splitting.

## G3 (not for chem 2C)

In a linear field (as experienced, for example, by the d electrons in [Ag(NH3)2]+), how would Crystal Field Theory arrange the d orbitals according to increasing energy. (Hint: Take z as the unique axis).

## G4.

When Pt has a coordination number of 6, an octahedral geometry is normally assumed. On the other hand, when Pt has a coordination number of 4, a square planar geometry is observed. A coordination compound has the empirical formula PtBr(en)(SCN)2 and is diamagnetic. In aqueous solution, each unit of this compound produces two complex ions. The ligand ethylenediamine (en) is present only in the cation while Br is present only in the anion. (a) What is the molecular formula of this compound (b) What is the formula of the complex cation ? (c) the complex anion ? (d) Give the d-electron configuration (using Crystal Field Theory) of the Pt in each of the complex ions.

## G5.

The octahedral structure is not the only possible six-possible coordinate structure. One possibility is a planar hexagonal structure, with the metal occupying the central position and with a ligand at each corner of the hexagon. Show that the existence of two and only two isomers of [Co(NH3)4Cl2]+ provides evidence against the hexagonal structure.

## G6.

The formation constants (Table E4) for two nickel complexes are shown below:

$[Ni(H_2O)_6]^{2+}(aq) + 6NH_3(aq) \rightarrow [Ni(NH_3)_6]^{2+}(aq) + 6H_2O(l)$

with $$K_f= 4 \times 10^8$$

$[Ni(H_2O)_6]^{2+}(aq) + 3en(aq) \rightarrow [Ni(en)_3]^{2+}(aq) + 6H_2O(l)$

with $$K_f= 2 \times 10^{18}$$

Although the donor atom is nitrogen in both instances, the formation constants are very different. With (en), it is ten orders of magnitude bigger. The generally larger formation constants for polydentate ligands is called the chelate effect. Explain this effect using themodynamic concepts.

## G7.

1. Draw all the geometric isomers for an MA2B4 complex.
2. Draw all the geometric isomers for an MA2B2 complex in a planar arrangement. For a tetrahedral arrangement, are geometric isomers possible?
3. Draw all the geometric isomers for an MA3B3 complex.
4. Draw all the geometric isomers for an MABCD complex in a planar arrangement. Are optical isomers possible?
5. Draw all the geometric isomers of [Cr(en)(NH3)2BrCl]+. Which of these isomers also has an optical isomer? Draw the various isomers.

## G8.

The following reduction potentials are known for various 3+ first-row transition metal ions in aqueous solution:

Mn3+(aq) + e- --> Mn2+(aq) Eo=1.51 V

Fe3+(aq) + e- --> Fe2+(aq) E0=0.77 V

Co3+(aq) + e- --> Co2+(aq) E0=1.84 V

Explain why the reduction potential for Fe3+ is abnormally low.

## G9. (not for chem 2C)

[NiCl4]2- is more likely to be tetrahedral while [Ni(CN)4]2- is more likely to be square planar. Explain.

## G10.

A Cu electrode is immersed in a solution that is 1.00 M in [Cu(NH3)4]2+ and 1.00M in NH3. When the cathode is a standard hydrogen electrode, the emf of the cell is found to be 0.08 V. What is the formation constant for [Cu(NH3)4]2+?