# Homework 4: Coordination Complexes

There are select solutions to these problems here.

## Q4.0

Write the ground-state electron configurations of these transition metal ions: $$V^{5+}$$, $$Au^{3+}$$, $$Fe^{2+}$$, $$Co^{2+}$$, $$Ti^{4+}$$?

## Q4.1

Which of these general structures for a complex ion would you expect to exhibit fac and mer isomerism? Explain.

1. tetrahedral
2. square-planar
3. octahedral

## Q4.2

If $$\ce{A}$$, $$\ce{B}$$, $$\ce{C}$$, $$\ce{D}$$ are four different ligands. How many geometric isomers will be found for square-planar $$\ce{[FeABCD]^2+}$$?

## Q4.3

Draw a structure for trans-dichlorobis(ethylenediamine)cobalt(III)ion. What kind of an isomer (geometric or optical) is the cis-dichlorobis(ethylenediamine)cobalt(III)ion.

Not for exam 1

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## Q4.9

Through orbital diagrams, write out the electron configurations for the following transition element atoms or ions:

1. Fe2+
2. Co2+
3. V4+
4. Sc2+
5. Ti2+
6. Cu

## Q4.10

Describe the oxidation states, magnetic properties, and trend of atomic radii of the transition metals in period 4.

## Q4.11

Balance a potential overall reaction to represent the following equation that uses $$MnO_4$$ as an oxidizing agent for the following half reaction:

$Fe^{2+} (aq) \rightarrow Fe^{3+}(aq) + e^-$

Assume the reaction is in acidic solution.

## Q4.12

Use data and the image provided below to construct standard electrode potentials relating the following manganese species to one another.

## Q4.13

What formula would you expect for the metal carbonyls of:

1. Zirconium (Zr),
2. Tungsten/wolfram (W),
3. Platinum (Pt)?
4. Explain the possible variations that determine the states and structures of different metal carbonyl structures.
5. For K[Mo(CO)6], how will the structure most likely bond?

## Q4.14

Write the electron configuration for each of the following transition elements and ions.

1. $$V$$
2. $$Mn^{3+}$$
3. $$Fe^{2+}$$
4. $$Cr$$
5. $$Co^{2+}$$

## Q4.15

Explain how transition elements compare with Alkali metals and Alkali-Earth metals regarding oxidation states, formation of complexes, colors of compounds, and magnetic properties.

## Q4.16

Complete and balance the following reaction:

$Mo_2O_3 (s) + Al (s) \rightarrow$

## Q4.17

Create potential half-reaction equations for the following reactions in acidic solutions.

1. $$Cr^{3+} (aq)$$ as a reducing agent.
2. $$Sc^{2+} (aq)$$ as an oxidizing agent.

## Q4.18

Use the given standard reduction potentials to construct a standard electrode potential diagram relation to the following species in acidic solution.

VO2+ (aq) + 2H+(aq) + e- --> V3+ (aq) + H2O (l) E0= 0.337V

V3+ (aq) + e- ---> V2+ (aq) E0= -0.255V

V2+(aq) + 2e- --> V(s) E0= -1.13

## Q4.19

What formulas would you expect for the metal carbonyls of:

1. Tungsten (W)
2. Ruthenium (Ru)
3. Technetium (Tc)

## Q4.20

Write the electron configurations for the following transition elements: a) Sc b) Cr3+ c) Mn7+ d) Fe2+ e) Cu f) Cu2+

Electronic Configurations

## Q4.21

Compare the transition metals with the main group metals. You may wish to consider oxidation states, formation of complexes, colors of compounds, and magnetic properties.

Oxidation States of Transition Metals

## Q4.21

Why does copper react with HCl, but not zinc?

The reason this happens is because Zn is more reactive than H. This allows the zinc to form a compound with the Cl atoms.

The equation would look like this: Zn (s) + HCl (aq) --> ZnCl2 + H2

Cu is LESS reactive than H so it makes the reaction not possible.

The Cell Potential

## Q4.22

Write plausible half-equations in acidic solution:

1. MnO4- as a reducing agent
2. Ni2+ as an oxidizing agent

We can do this by referring to the standard electrode (reduction) potentials.

a) MnO4- (aq) + 4H+ (aq) + 2e- --> MnO2(s) + H2O (l)

b) Oxidizing agent = reduced, so you want to flip the equation so the electrons are on the right hand side of the arrows

Ni (s) --> Ni2+ (aq) + 2e-

The Cell Potential

## Q4.23

Construct a cell diagram from the given reaction couple: Cr3+ / Cr2+ E'cell = -0.9 V ; H+/H2 E'cell = 0 V

Pt (s) l Cr3+(aq) , Cr2+ (aq) ll H+ (aq) l H2 (g) l Pt (s)

Anode (oxidation) ll cathode (reduction)

The Cell Potential