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Chemistry The Central Science

Theodore L. Brown

Chapter 23

Transition Metals and Coordination Chemistry - all with Video Answers

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Chapter Questions

03:05

Problem 1

The three graphs below show the variation in radius, effective nuclear charge, and maximum oxidation state for the transition metals of period 4. In each part below identify which property is being plotted. [ Section 23.1]

April Berlyoung
April Berlyoung
Numerade Educator
08:13

Problem 2

Draw the structure for Pt $($ en $) \mathrm{Cl}_{2}$ and use it to answer the following questions: (a) What is the coordination number for platinum in this complex? (b) What is the coordination geometry? (c) What is the oxidation state of the platinum? (d) How many unpaired electrons are there? [Sections 23.2 and 23.6]

Qiao Ruan
Qiao Ruan
Numerade Educator
06:02

Problem 3

Draw the Lewis structure for the ligand shown here. (a) Which atoms can serve as donor atoms? Classify this ligand as monodentate, bidentate, or polydentate. (b) How many of these ligands are needed to fill the coordination sphere in an octahedral complex? [Section 23.2]

April Berlyoung
April Berlyoung
Numerade Educator
05:51

Problem 4

Four-coordinate metals can have either a tetrahedral or a square-planar geometry; both possibilities are shown here for $\left[\mathrm{PtCl}_{2}\left(\mathrm{NH}_{3}\right)_{2}\right] .$ (a) $\mathrm{What}$ is the name of this molecule? (b) Would the tetrahedral molecule have a geometric isomer? (c) Would the tetrahedral molecule be diamagnetic or paramagnetic? (d) Would the square-planar molecule have a geometric isomer? (e) Would the square-planar molecule be diamagnetic or paramagnetic? (f) Would determining the number of geometric isomers help you distinguish between the tetrahedral and square-planar geometries? (g) Would measuring the molecule's response to a magnetic field help you distinguish between the two geometries? [Sections 23.4-23.6 ]

Qiao Ruan
Qiao Ruan
Numerade Educator
01:35

Problem 5

There are two geometric isomers of octahedral complexes of the type $\mathrm{MA}_{3} \mathrm{X}_{3}$ , where $\mathrm{M}$ is a metal and $\mathrm{A}$ and $\mathrm{X}$ are monodentate ligands. Of the complexes shown here, which are identical to $(1)$ and which are the geometric isomers of $(1) ?[$ Section 23.4$]$

Arun Bana
Arun Bana
Numerade Educator
06:02

Problem 6

Which of the complexes shown here are chiral? [Section 23.4]

David Collins
David Collins
Numerade Educator
01:43

Problem 7

The solutions shown here each have an absorption spectrum with a single absorption peak like that shown in Figure 23.26. What color does each solution absorb most strongly? [ Section 23.5]

April Berlyoung
April Berlyoung
Numerade Educator
08:01

Problem 8

Which of these crystal-field splitting diagrams represents: (a) a weak-field octahedral complex of $\mathrm{Fe}^{3+},(\mathbf{b})$ a strong field octahedral complex of $\mathrm{Fe}^{3+},$ (c) a tetrahedral complex of $\mathrm{Fe}^{3+},(\mathbf{d})$ a tetrahedral complex of $\mathrm{Ni}^{2+} ?$ (The diagrams do not indicate the relative magnitudes of $\Delta . )[$ Section 23.6$]$

Qiao Ruan
Qiao Ruan
Numerade Educator
04:04

Problem 9

In the linear crystal-field shown here, the negative charges are on the $z$-axis. Using Figure 23.28 as a guide, predict which of the following choices most accurately describes the splitting of the $d$ orbitals in a linear crystal-field? [Section 23.6$]$

Arun Bana
Arun Bana
Numerade Educator
03:47

Problem 10

Two Fe(II) complexes are both low spin but have different ligands. A solution of one is green and a solution of the other is red. Which solution is likely to contain the complex that has the stronger-field ligand? [Section 23.6]

Qiao Ruan
Qiao Ruan
Numerade Educator
01:37

Problem 11

The lanthanide contraction explains which of the following periodic trends? (a) The atomic radii of the
transitionmetals first decrease and then increase when moving horizontally across each period. (b) When forming ions the period 4 transition metals lose their 4$s$ electrons before their 3$d$ electrons. (c) The radii of the period 5 transition metals $(\mathrm{Y}-\mathrm{Cd})$ are very similar to the radii of the period 6 transition metals $(\mathrm{Lu}-\mathrm{Hg}).$

April Berlyoung
April Berlyoung
Numerade Educator
03:08

Problem 12

Which periodic trend is partially responsible for the observation that the maximum oxidation state of the transition-metal elements peaks near groups 7 $\mathrm{B}$ and 8 $\mathrm{B} ?$ (a) The number of valence electrons reaches a maximum at group 8 $\mathrm{B} .$ (b) The effective nuclear charge increases on moving left across each period. (c) The radii of the transition-metal elements reach a minimum for group $8 \mathrm{B},$ and as the size of the atoms decreases it becomes easier to remove electrons.

Qiao Ruan
Qiao Ruan
Numerade Educator
02:43

Problem 13

For each of the following compounds, determine the electron configuration of the transition-metal ion. $(\mathbf{a})$ TiO, $(\mathbf{b}) \mathrm{TiO}_{2},(\mathbf{c}) \mathrm{NiO},(\mathbf{d}) \mathrm{ZnO}$ .

April Berlyoung
April Berlyoung
Numerade Educator
02:28

Problem 14

Among the period 4 transition metals $(\mathrm{Sc}-\mathrm{Zn}),$ which elements do not form ions where there are partially filled 3d orbitals?

Qiao Ruan
Qiao Ruan
Numerade Educator
02:40

Problem 15

Write out the ground-state electron configurations of (a) $\mathrm{Ti}^{3+},(\mathbf{b}) \mathrm{Ru}^{2+},(\mathbf{c}) \mathrm{Au}^{3+},(\mathbf{d}) \mathrm{Mn}^{4+} .$

April Berlyoung
April Berlyoung
Numerade Educator
05:52

Problem 16

How many electrons are in the valence $d$ orbitals in these transition-metal ions? (a) $\mathrm{Co}^{3+},(\mathbf{b}) \mathrm{Cu}^{+},(\mathbf{c}) \mathrm{Cd}^{2+},(\mathbf{d}) \mathrm{Os}^{3+}.$

Qiao Ruan
Qiao Ruan
Numerade Educator
01:50

Problem 17

Which type of substance is attracted by a magnetic field, a diamagnetic substance or a paramagnetic substance?

April Berlyoung
April Berlyoung
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01:50

Problem 18

Which type of magnetic material cannot be used to make permanent magnets, a ferromagnetic substance, an anti-ferromagnetic substance, or a ferrimagnetic substance?

Qiao Ruan
Qiao Ruan
Numerade Educator
01:40

Problem 19

What kind of magnetism is exhibited by this diagram:

April Berlyoung
April Berlyoung
Numerade Educator
05:46

Problem 20

The most important oxides of iron are magnetite, $\mathrm{Fe}_{3} \mathrm{O}_{4}$ and hematite, $\mathrm{Fe}_{2} \mathrm{O}_{3} .$ (a) What are the oxidation states of iron in these compounds? (b) One of these iron oxides is ferrimagnetic, and the other is antiferromagnetic. Which iron oxide is more likely to be ferrimagnetic? Explain.

Qiao Ruan
Qiao Ruan
Numerade Educator
01:54

Problem 21

(a) Using Werner's definition of valence, which property is the same as oxidation number, primary valence or secondary valence? (b) What term do we normally use for the other type of valence? (c) Why can $\mathrm{NH}_{3}$ serve as a ligand but BH $_{3}$ cannot?

April Berlyoung
April Berlyoung
Numerade Educator
02:27

Problem 22

Which species are more likely to act as ligands? (a) Positively charged ions or negatively charged ions? (b) Neutral molecules that are polar or those that are nonpolar?

Qiao Ruan
Qiao Ruan
Numerade Educator
04:06

Problem 23

A complex is written as $\mathrm{NiBr}_{2} \cdot 6 \mathrm{NH}_{3}$ . (a) What is the oxidation state of the Ni atom in this complex? (b) What is the likely coordination number for the complex? (c) If the complex is treated with excess AgNO $_{3}(a q),$ how many moles of AgBr will precipitate per mole of complex?

April Berlyoung
April Berlyoung
Numerade Educator
06:35

Problem 24

Crystals of hydrated chromium(III) chloride are green, have an empirical formula of $\mathrm{CrCl}_{3} \cdot 6 \mathrm{H}_{2} \mathrm{O},$ and are highly soluble, (a) Write the complex ion that exists in this compound. (b) If the complex is treated with excess $\mathrm{AgNO}_{3}(a q)$ how many moles of AgCl will precipitate per mole of $\mathrm{CrCl}_{3} \cdot 6 \mathrm{H}_{2} \mathrm{O}$ dissolved in solution? (c) Crystals of anhydrous chromium(III) chloride are violet and insoluble in aqueous solution. The coordination geometry of chromium in these crystals is octahedral, as is almost always the case for $\mathrm{Cr}^{3+} .$ How can this be the case if the ratio of $\mathrm{Cr}$ to Clis not 1:6 ?

Qiao Ruan
Qiao Ruan
Numerade Educator
05:48

Problem 25

Indicate the coordination number and the oxidation number of the metal for each of the following complexes:
(a) $\mathrm{Na}_{2}\left[\mathrm{CdCl}_{4}\right]$
(b) $\mathrm{K}_{2}\left[\mathrm{MoOCl}_{4}\right]$
(c) $\left[\mathrm{Co}\left(\mathrm{NH}_{3}\right)_{4} \mathrm{Cl}_{2}\right] \mathrm{Cl}$
(d) $\left[\mathrm{Ni}(\mathrm{CN})_{5}\right]^{3-}$
(e) $\mathrm{K}_{3}\left[\mathrm{V}\left(\mathrm{C}_{2} \mathrm{O}_{4}\right)_{3}\right]$
(f) $\left[\mathrm{Zn}(\mathrm{en})_{2}\right] \mathrm{Br}_{2}$

April Berlyoung
April Berlyoung
Numerade Educator
12:52

Problem 26

Indicate the coordination number and the oxidation number of the metal for each of the following complexes:
(a) $\mathrm{K}_{3}\left[\mathrm{Co}(\mathrm{CN})_{6}\right]$
(b) $\mathrm{Na}_{2}\left[\mathrm{CdBr}_{4}\right]$
(c) $\left[\mathrm{Pt}(\mathrm{en})_{3}\right]\left(\mathrm{ClO}_{4}\right)_{4}$
(d) $\left[\mathrm{Co}(\mathrm{en})_{2}\left(\mathrm{C}_{2} \mathrm{O}_{4}\right)\right]^{+}$
(e) $\mathrm{NH}_{4}\left[\mathrm{Cr}\left(\mathrm{NH}_{3}\right)_{2}(\mathrm{NCS})_{4}\right]$
(f) $\left[\mathrm{Cu}(\mathrm{bipy})_{2} \mathrm{I}\right] \mathrm{I}$

Qiao Ruan
Qiao Ruan
Numerade Educator
04:43

Problem 27

For each of the following molecules or polyatomic ions, draw the Lewis structure and indicate if it can act as a monodentate ligand, a bidentate ligand, or is unlikely to act as a ligand at all: (a) ethylamine, $\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{NH}_{2}$ , (b) trimethylphosphine, $\mathrm{P}\left(\mathrm{CH}_{3}\right)_{3},$ (c) carbonate, $\mathrm{CO}_{3}^{2-},$ $(\mathbf{d})$ ethane $, \mathrm{C}_{2} \mathrm{H}_{6}.$

April Berlyoung
April Berlyoung
Numerade Educator
05:24

Problem 28

For each of the following polydentate ligands, determine (i) the maximum number of coordination sites that the ligand can occupy on a single metal ion and (ii) the number and type of donor atoms in the ligand: (a) ethylenediamine $($ en $),(\mathbf{b})$ bipyridine (bipy), (c) the oxalate anion $\left(\mathrm{C}_{2} \mathrm{O}_{4}^{2-}\right),$ (d) the $2-$ ion of the porphine molecule (Figure 23.13) $(\mathbf{e})[\mathrm{EDTA}]^{4-}$

Qiao Ruan
Qiao Ruan
Numerade Educator
07:05

Problem 29

Polydentate ligands can vary in the number of coordination positions they occupy. In each of the following, identify the polydentate ligand present and indicate the probable number of coordination positions it occupies:
(a) $\left[\mathrm{Co}\left(\mathrm{NH}_{3}\right)_{4}(0-\mathrm{phen})\right] \mathrm{Cl}_{3}$
(b) $\left[\mathrm{Cr}\left(\mathrm{C}_{2} \mathrm{O}_{4}\right)\left(\mathrm{H}_{2} \mathrm{O}\right)_{4}\right] \mathrm{Br}$
(c) $[\mathrm{Ca}(\mathrm{EDTA})]^{2-}$
(d) $\left[\mathrm{Zn}(\mathrm{en})_{2}\right]\left(\mathrm{ClO}_{4}\right)_{2}$

April Berlyoung
April Berlyoung
Numerade Educator
07:27

Problem 30

Indicate the likely coordination number of the metal in each of the following complexes:
(a) $\left[\mathrm{Rh}(\mathrm{bipy})_{3}\right]\left(\mathrm{NO}_{3}\right)_{3}$
(b) $\mathrm{Na}_{3}\left[\mathrm{Co}\left(\mathrm{C}_{2} \mathrm{O}_{4}\right)_{2} \mathrm{Cl}_{2}\right]$
(c) $\left[\mathrm{Cr}(o-\mathrm{phen})_{3}\right]\left(\mathrm{CH}_{3} \mathrm{COO}\right)_{3}$
(d) $\mathrm{Na}_{2}[\mathrm{Co}(\mathrm{EDTA}) \mathrm{Br}]$

Qiao Ruan
Qiao Ruan
Numerade Educator
02:25

Problem 31

For each of the following pairs, identify the molecule or ion that is more likely to act as a ligand in a metal complex: (a) acetonitrile $\left(\mathrm{CH}_{3} \mathrm{CN}\right)$ or ammonium $\left(\mathrm{NH}_{4}^{+}\right)$ (b) hydride $\left(\mathrm{H}^{-}\right)$ or hydronium $\left(\mathrm{H}_{3} \mathrm{O}^{+}\right),(\mathbf{c})$ carbon monoxide $(\mathrm{CO})$ or methane $\left(\mathrm{CH}_{4}\right)$ .

April Berlyoung
April Berlyoung
Numerade Educator
02:58

Problem 32

Pyridine $\left(\mathrm{C}_{5} \mathrm{H}_{5} \mathrm{N}\right),$ abbreviated py, is the molecule (a) Would you expect pyridine to act as a monodentate or bidentate ligand? (b) For the equilibrium reaction
$$\left[\mathrm{Ru}(\mathrm{py})_{4}(\mathrm{bipy})\right]^{2+}+2 \mathrm{py} \Longrightarrow\left[\mathrm{Ru}(\mathrm{py})_{6}\right]^{2+}+\mathrm{bipy}$$
would you predict the equilibrium constant to be larger or smaller than one?

Qiao Ruan
Qiao Ruan
Numerade Educator
01:53

Problem 33

True or false? The following ligand can act as a bidentate ligand?

April Berlyoung
April Berlyoung
Numerade Educator
10:21

Problem 34

When silver nitrate is reacted with the molecular base ortho-phenanthroline, colorless crystals form that contain the transition-metal complex shown below.(a) What is the coordination geometry of silver in this complex? (b) Assuming no oxidation or reduction occurs during the reaction, what is charge of the complex shown here? (c) Do you expect any nitrate ions will be present in the crystal? (d) Write a formula for the compound that forms in this reaction. (e) Use the accepted nomenclature to write the name of this compound.

Qiao Ruan
Qiao Ruan
Numerade Educator
01:13

Problem 35

Write the formula for each of the following compounds, being sure to use brackets to indicate the coordination sphere:
(a) hexamminechromium(III) nitrate
(b) tetraamminecarbonatocobalt(III) sulfate
(c) dichlorobis(ethylenediamine)platinum(IV) bromide
(d) potassium diaquatetrabromovanadate(III)
(e) bis(ethylenediamine) zinc(II) tetraiodomercurate(II)

Ronald Prasad
Ronald Prasad
Numerade Educator
11:01

Problem 36

Write the formula for each of the following compounds, being sure to use brackets to indicate the coordination sphere:
(a) tetraaquadibromomanganese(III) perchlorate
(b) bis(bipyridyl)cadmium(II) chloride
(c) potassium tetrabromo (ortho-phenanthroline) cobaltate(III)
(d) cesium diamminetetracyanochromate(III)
(e) tris(ethylenediamine) rhodium(III) tris(oxalato)-cobaltate(III)

Qiao Ruan
Qiao Ruan
Numerade Educator
09:00

Problem 37

Write the names of the following compounds, using the standard nomenclature rules for coordination complexes:
(a) $\left[\mathrm{Rh}\left(\mathrm{NH}_{3}\right)_{4} \mathrm{Cl}_{2}\right] \mathrm{Cl}$
(b) $\mathrm{K}_{2}\left[\mathrm{TiCl}_{6}\right]$
(c) $\mathrm{MoOCI}_{4}$
(d) $\left[\operatorname{Pt}\left(\mathrm{H}_{2} \mathrm{O}\right)_{4}\left(\mathrm{C}_{2} \mathrm{O}_{4}\right)\right] \mathrm{Br}_{2}$

April Berlyoung
April Berlyoung
Numerade Educator
06:42

Problem 38

Write names for the following coordination compounds:
(a) $\left[\mathrm{Cd}(\mathrm{en}) \mathrm{Cl}_{2}\right]$
(b) $\mathrm{K}_{4}\left[\mathrm{Mn}(\mathrm{CN})_{6}\right]$
(c) $\left[\mathrm{Cr}\left(\mathrm{NH}_{3}\right)_{5}\left(\mathrm{CO}_{3}\right)\right] \mathrm{Cl}$
(d) $\left[\operatorname{Ir}\left(\mathrm{NH}_{3}\right)_{4}\left(\mathrm{H}_{2} \mathrm{O}\right)_{2}\right]\left(\mathrm{NO}_{3}\right)_{3}$

Qiao Ruan
Qiao Ruan
Numerade Educator
04:04

Problem 39

Consider the following three complexes:
(Complex 1) $\left[\mathrm{Co}\left(\mathrm{NH}_{3}\right)_{4} \mathrm{Br}_{2}\right] \mathrm{Cl}$
(Complex 2) $\left[\mathrm{Pd}\left(\mathrm{NH}_{3}\right)_{2}(\mathrm{ONO})_{2}\right]$
(Complex 3) $\left[\mathrm{V}(\mathrm{en})_{2} \mathrm{Cl}_{2}\right]^{+},$
Which of the three complexes can have (a) geometric isomers, (b) linkage isomers, (c) optical isomers, (d) coordination- sphere isomers?

April Berlyoung
April Berlyoung
Numerade Educator
08:17

Problem 40

Consider the following three complexes:
(Complex 1) $\left[\mathrm{Co}\left(\mathrm{NH}_{3}\right)_{5} \mathrm{SCN}\right]^{2+}$
(Complex 2) $\left[\mathrm{Co}\left(\mathrm{NH}_{3}\right)_{3} \mathrm{Cl}_{3}\right]^{2+}$
(Complex 3) $\mathrm{CoClBr} \cdot 5 \mathrm{NH}_{3}$
Which of the three complexes can have (a) geometric isomers, (b) linkage isomers, (c) optical isomers, (d) coordination-sphere isomers?

Qiao Ruan
Qiao Ruan
Numerade Educator
03:16

Problem 41

A four-coordinate complex $\mathrm{MA}_{2} \mathrm{B}_{2}$ is prepared and found to have two different isomers. Is it possible to determine from this information whether the complex is square planar or tetrahedral? If so, which is it?

April Berlyoung
April Berlyoung
Numerade Educator
02:58

Problem 42

Consider an octahedral complex $\mathrm{MA}_{3} \mathrm{B}_{3} .$ How many geo- metric isomers are expected for this compound? Will any of the isomers be optically active? If so, which ones?

Qiao Ruan
Qiao Ruan
Numerade Educator
06:26

Problem 43

Determine if each of the following complexes exhibits geometric isomerism. If geometric isomers exist, determine how many there are. (a) tetrahedral $\left[\operatorname{Cd}\left(\mathrm{H}_{2} \mathrm{O}\right)_{2} \mathrm{Cl}_{2}\right],(\mathbf{b})$ square-planar $\left[\operatorname{IrCl}_{2}\left(\mathrm{PH}_{3}\right)_{2}\right]^{-},(\mathbf{c})$ octahedral $\left[\mathrm{Fe}(o-\mathrm{phen})_{2} \mathrm{Cl}_{2}\right]^{+}.$

April Berlyoung
April Berlyoung
Numerade Educator
03:52

Problem 44

Determine if each of the following complexes exhibits geometric isomerism. If geometric isomers exist, determine how many there are. (a) [ Rh(bipy) $(o-$ phen $)_{2} ]^{3+},$ $(\mathbf{b})\left[\mathrm{Co}\left(\mathrm{NH}_{3}\right)_{3}(\mathrm{bipy}) \mathrm{Br}\right]^{2+},(\mathbf{c})$ square-planar $\left[\mathrm{Pd}(\mathrm{en})(\mathrm{CN})_{2}\right].$

Qiao Ruan
Qiao Ruan
Numerade Educator
04:16

Problem 45

Determine if each of the following metal complexes is chiral and therefore has an optical isomer: (a) tetrahedral $\left[\mathrm{Zn}\left(\mathrm{H}_{2} \mathrm{O}\right)_{2} \mathrm{Cl}_{2}\right],(\mathbf{b})$ octahedral trans-[Ru(bipy) $)_{2} \mathrm{Cl}_{2} ],(\mathbf{c})$ octahedral cis-[Ru(bipy) $_{2} \mathrm{Cl}_{2} ] .$

April Berlyoung
April Berlyoung
Numerade Educator
04:08

Problem 46

Determine if each of the following metal complexes is chiral and therefore has an optical isomer: (a) square planar $\left[\mathrm{Pd}(\mathrm{en})(\mathrm{CN})_{2}\right],(\mathbf{b})$ octahedral $\left[\mathrm{Ni}(\mathrm{en})\left(\mathrm{NH}_{3}\right)_{4}\right]^{2+},(\mathbf{c})$ octahe-
dral $\operatorname{cis}-\left[\mathrm{V}(\mathrm{en})_{2} \mathrm{ClBr}\right]$

Qiao Ruan
Qiao Ruan
Numerade Educator
04:33

Problem 47

(a) If a complex absorbs light at $610 \mathrm{nm},$ what color would you expect the complex to be? (b) What is the energy in joules of a photon with a wavelength of 610 $\mathrm{nm} ?$ (c) What is the energy of this absorption in $\mathrm{kJ} / \mathrm{mol}$ ?

April Berlyoung
April Berlyoung
Numerade Educator
04:46

Problem 48

(a) A complex absorbs photons with an energy of 4.51 $\times 10^{-19} \mathrm{J}$ . What is the wavelength of these photons? (b) If this is the only place in the visible spectrum where the complex absorbs light, what color would you expect the complex to be?

Qiao Ruan
Qiao Ruan
Numerade Educator
01:41

Problem 49

Identify each of the following coordination complexes as either diamagnetic or paramagnetic:
(a) $\left[\mathrm{ZnCl}_{4}\right]^{2-}$
(b) $\left[\mathrm{Pd}\left(\mathrm{NH}_{3}\right)_{2} \mathrm{Cl}_{2}\right]$
(c) $\left[\mathrm{V}\left(\mathrm{H}_{2} \mathrm{O}\right)_{6}\right]^{3+}$
(d) $\left[\mathrm{Ni}(\mathrm{en})_{3}\right]^{2+}$

Rashmi Sinha
Rashmi Sinha
Numerade Educator
16:37

Problem 50

Identify each of the following coordination complexes as either diamagnetic or paramagnetic:
(a) $\left[\mathrm{Ag}\left(\mathrm{NH}_{3}\right)_{2}\right]^{+}$
(b) square planar $\left[\mathrm{Cu}\left(\mathrm{NH}_{3}\right)_{4}\right]^{2+}$
(c) $\left[\mathrm{Ru}(\mathrm{bipy})_{3}\right]^{2+}$
(d) $\left[\mathrm{CoCl}_{4}\right]^{2-}$

Qiao Ruan
Qiao Ruan
Numerade Educator
02:25

Problem 51

If the lobes of a given $d$-orbital point directly at the ligands, will an electron in that orbital have a higher or lower energy than an electron in a $d$-orbital whose lobes do not point directly at the ligands?

April Berlyoung
April Berlyoung
Numerade Educator
02:38

Problem 52

The lobes of which $d$ orbitals point directly between the ligands in (a) octahedral geometry, (b) tetrahedral geometry?

Qiao Ruan
Qiao Ruan
Numerade Educator
04:00

Problem 53

(a) Sketch a diagram that shows the definition of the crystal-field splitting energy $(\Delta)$ for an octahedral crystal-field. (b) What is the relationship between the magnitude of $\Delta$ and
the energy of the $d$-$d$ transition for a $d^{1}$ complex? (c) Calculate $\Delta$ in $\mathrm{k} J / \mathrm{mol}$ if a $d^{1}$ complex has an absorption maximum at 545 $\mathrm{nm} .$

April Berlyoung
April Berlyoung
Numerade Educator
02:25

Problem 54

As shown in Figure 23.26, the $d-d$ transition of $\left[\mathrm{Ti}\left(\mathrm{H}_{2} \mathrm{O}\right)_{6}\right]^{3+}$ produces an absorption maximum at a wavelength of about 500 $\mathrm{nm}$ . (a) What is the magnitude of $\Delta$ for $\left[\mathrm{Ti}\left(\mathrm{H}_{2} \mathrm{O}\right)_{6}\right]^{3+}$ in $\mathrm{kJ} / \mathrm{mol} ?$ (b) How would the magnitude of $\Delta$change if the $\mathrm{H}_{2} \mathrm{O}$ ligands in $\left[\mathrm{Ti}\left(\mathrm{H}_{2} \mathrm{O}\right)_{6}\right]^{3+}$ were replaced with $\mathrm{NH}_{3}$ ligands?

Qiao Ruan
Qiao Ruan
Numerade Educator
03:20

Problem 55

The colors in the copper-containing minerals malachite, which is green and has an empirical formula of $\mathrm{Cu}_{2} \mathrm{CO}_{3}$ $(\mathrm{OH})_{2},$ and azurite, which is blue and has an empirical formula of $\mathrm{Cu}_{3}\left(\mathrm{CO}_{3}\right)_{2}(\mathrm{OH})_{2},$ come from a single $d-d$ transition in each compound. The compounds are sometimes found together in nature as shown here. (a) What is the electron configuration of the copper ion in each mineral? (b) Based on their colors, in which compound would you predict the crystal-field splitting $\Delta$ is larger?

April Berlyoung
April Berlyoung
Numerade Educator
02:53

Problem 56

The color and wavelength of the absorption maximum for $\left[\mathrm{Ni}\left(\mathrm{H}_{2} \mathrm{O}\right)_{6}\right]^{2+},\left[\mathrm{Ni}\left(\mathrm{NH}_{3}\right)_{6}\right]^{2+},$ and $\left[\mathrm{Ni}(\mathrm{en})_{3}\right]^{2+}$ are given in Figure 23.30. The absorption maximum for the $[$ Ni(bipy $)_{3} ]^{2+}$ ion occurs at about 520 $\mathrm{nm}$ . (a) What color would you expect for the $\left[\mathrm{Ni}(\mathrm{bipy})_{3}\right]^{2+}$ ion? (b) Based on these data, where would you put bipy in the spectrochemical series?

Qiao Ruan
Qiao Ruan
Numerade Educator
03:53

Problem 57

Give the number of (valence) $d$ electrons associated with the central metal ion in each of the following complexes: (a) $\mathrm{K}_{3}\left[\mathrm{TiCl}_{6}\right],(\mathbf{b}) \mathrm{Na}_{3}\left[\mathrm{Co}\left(\mathrm{NO}_{2}\right)_{6}\right],(\mathbf{c})\left[\mathrm{Ru}(\mathrm{en})_{3}\right] \mathrm{Br}_{3},$ $(\mathbf{d})[\mathrm{Mo}(\mathrm{EDTA})] \mathrm{ClO}_{4},(\mathbf{e}) \mathrm{K}_{3}\left[\mathrm{ReCl}_{6}\right].$

April Berlyoung
April Berlyoung
Numerade Educator
07:44

Problem 58

Give the number of (valence) $d$ electrons associated with the central metal ion in each of the following complexes: (a) $\mathrm{K}_{3}\left[\mathrm{Fe}(\mathrm{CN})_{6}\right (\mathbf{b})\left[\mathrm{Mn}\left(\mathrm{H}_{2} \mathrm{O}\right)_{6}\right]\left(\mathrm{NO}_{3}\right)_{2},(\mathbf{c}) \mathrm{Na}\left[\mathrm{Ag}(\mathrm{CN})_{2}\right]$ (d) $\left[\mathrm{Cr}\left(\mathrm{NH}_{3}\right)_{4} \mathrm{Br}_{2}\right] \mathrm{ClO}_{4},(\mathbf{e})[\operatorname{Sr}(\mathrm{EDTA})]^{2-}$

Qiao Ruan
Qiao Ruan
Numerade Educator
01:55

Problem 59

A classmate says, "A weak-field ligand usually means the complex is high spin." Is your classmate correct? Explain.

April Berlyoung
April Berlyoung
Numerade Educator
02:09

Problem 60

For a given metal ion and set of ligands, is the crystal-field splitting energy larger for a tetrahedral or an octahedral geometry?

Qiao Ruan
Qiao Ruan
Numerade Educator
05:04

Problem 61

For each of the following metals, write the electronic configuration of the atom and its $2+$ ion: (a) $\mathrm{Mn},(\mathbf{b}) \mathrm{Ru},(\mathbf{c}) \mathrm{Rh}$. Draw the crystal-field energy-level diagram for the $d$ orbitals of an octahedral complex, and show the placement of the $d$ electrons for each $2+$ ion, assuming a strong-field complex. How many unpaired electrons are there in each case?

April Berlyoung
April Berlyoung
Numerade Educator
03:35

Problem 62

For each of the following metals, write the electronic configuration of the atom and its $3+$ ion: (a) Fe, (b) Mo, (c) Co. Draw the crystal-field energy-level diagram for the $d$ orbitals of an octahedral complex, and show the placement of the $d$ electrons for each $3+$ ion, assuming a weak-field complex. How many unpaired electrons are there in each case?

Qiao Ruan
Qiao Ruan
Numerade Educator
05:37

Problem 63

Draw the crystal-field energy-level diagrams and show the placement of $d$ electrons for each of the following: (a) $\left[\mathrm{Cr}\left(\mathrm{H}_{2} \mathrm{O}\right)_{6}\right]^{2+}$ (four unpaired electrons), $(\mathbf{b})\left[\operatorname{Mn}\left(\mathrm{H}_{2} \mathrm{O}\right)_{6}\right]^{2+}$ (a high-spin complex), (c) $\left[\mathrm{Ru}\left(\mathrm{NH}_{3}\right)_{5}\left(\mathrm{H}_{2} \mathrm{O}\right)\right]^{2+}$ (a low-spin complex) $(\mathbf{d})\left[\operatorname{Ir} \mathrm{Cl}_{6}\right]^{2-}$ (a low-spin complex) $(\mathbf{e})\left[\mathrm{Cr}(\mathrm{en})_{3}\right]^{3+}$ $(\mathbf{f})\left[\mathrm{NiF}_{6}\right]^{4-}.$

April Berlyoung
April Berlyoung
Numerade Educator
07:57

Problem 64

Draw the crystal-field energy-level diagrams and show the placement of electrons for the following complexes: (a) $\left[\mathrm{VCl}_{6}\right]^{3-},$ (b) $\left[\mathrm{FeF}_{6}\right]^{3-}$ | (a high-spin complex) $(\mathbf{c})\left[\mathrm{Ru}(\mathrm{bipy})_{3}\right]^{3+}$ (a low-spin complex), $(\mathbf{d})\left[\mathrm{NiCl}_{4}\right]^{2-}$ (tetrahedral), ( e) $\left[\mathrm{PtBr}_{6}\right]^{2-},(\mathbf{f})\left[\mathrm{Ti}(\mathrm{en})_{3}\right]^{2+}$.

Qiao Ruan
Qiao Ruan
Numerade Educator
01:54

Problem 65

The complex $\left[\mathrm{Mn}\left(\mathrm{NH}_{3}\right)_{6}\right]^{2+}$ contains five unpaired electrons. Sketch the energy-level diagram for the $d$ orbitals, and indicate the placement of electrons for this complex ion. Is the ion a high-spin or a low-spin complex?

April Berlyoung
April Berlyoung
Numerade Educator
02:34

Problem 66

The ion $\left[\mathrm{Fe}(\mathrm{CN})_{6}\right]^{3-}$ has one unpaired electron, whereas $\left[\mathrm{Fe}(\mathrm{NCS})_{6}\right]^{3-}$ has five unpaired electrons. From these results, what can you conclude about whether each complex is high spin or low spin? What can you say about the placement of $\mathrm{NCS}^{-}$ in the spectrochemical series?

Qiao Ruan
Qiao Ruan
Numerade Educator
02:13

Problem 67

The Curie temperature is the temperature at which a ferromagnetic solid switches from ferromagnetic to paramagnetic, and for nickel, the Curie temperature is $354^{\circ} \mathrm{C}$. Knowing this, you tie a string to two paper clips made of nickel and hold the paper clips near a permanent magnet. The magnet attracts the paper clips, as shown in the photograph on the left. Now you heat one of the paper clips with a cigarette lighter, and the clip drops (right photograph). Explain what happened.

April Berlyoung
April Berlyoung
Numerade Educator
02:12

Problem 68

Explain why the transition metals in periods 5 and 6 have nearly identical radii in each group.

Qiao Ruan
Qiao Ruan
Numerade Educator
02:05

Problem 69

Based on the molar conductance values listed here for the series of platinum(IV) complexes, write the formula for each complex so as to show which ligands are in the coordination sphere of the metal. By way of example, the molar conductances of 0.050$M \mathrm{NaCl}$ and $\mathrm{BaCl}_{2}$ are 107 $\mathrm{ohm}^{-1}$ and 197 $\mathrm{ohm}^{-1}$ , respectively.

Arun Bana
Arun Bana
Numerade Educator
01:36

Problem 70

(a) A compound with formula $\mathrm{RuCl}_{3}$ $\cdot 5 \mathrm{H}_{2} \mathrm{O}$ is dissolved in water, forming a solution that is approximately the same color as the solid. Immediately after forming the solution, the addition of excess AgNO $_{3}(a q)$ forms 2 mol of solid AgCl per mole of complex. Write the formula for the compound, showing which ligands are likely to be present in the coordination sphere. (b) After a solution of $\mathrm{RuCl}_{3}$ $\cdot 5 \mathrm{H}_{2} \mathrm{O}$ has stood for about a year, addition of $\mathrm{AgNO}_{3}(a q)$ precipitates 3 mol of AgCl per mole of complex. What has happened in the ensuing time?

Qiao Ruan
Qiao Ruan
Numerade Educator
12:09

Problem 71

Sketch the structure of the complex in each of the following compounds and give the full compound name:
(a) $\operatorname{cis}-\left[\operatorname{Co}\left(\mathrm{NH}_{3}\right)_{4}\left(\mathrm{H}_{2} \mathrm{O}\right)_{2}\right]\left(\mathrm{NO}_{3}\right)_{2}$
(b) $\mathrm{Na}_{2}\left[\mathrm{Ru}\left(\mathrm{H}_{2} \mathrm{O}\right) \mathrm{Cl}_{5}\right]$
(c) $\operatorname{trans} \mathrm{NH}_{4}\left[\mathrm{Co}\left(\mathrm{C}_{2} \mathrm{O}_{4}\right)_{2}\left(\mathrm{H}_{2} \mathrm{O}\right)_{2}\right]$
(d) $\operatorname{cis}-\left[\operatorname{Ru}(\mathrm{en})_{2} \mathrm{Cl}_{2}\right]$

April Berlyoung
April Berlyoung
Numerade Educator
03:06

Problem 72

Which complex ions in Exercise 23.71 have optical isomers?

Qiao Ruan
Qiao Ruan
Numerade Educator
06:50

Problem 73

The molecule dimethylphosphinoethane $\left[\left(\mathrm{CH}_{3}\right)_{2} \mathrm{P} \mathrm{CH}_{2} \mathrm{CH}_{2}\right.$ $\mathrm{P}\left(\mathrm{CH}_{3}\right)_{2},$ which is abbreviated dmpe] is used as a ligand for some complexes that serve as catalysts. A complex that contains this ligand is Mo $(\mathrm{CO})_{4}(\mathrm{dmpe})$ . (a) Draw the Lewis structure for dmpe, and compare it with ethylenediamine as a coordinating ligand. (b) What is the oxidation state of Mo in $\mathrm{Na}_{2}\left[\mathrm{Mo}(\mathrm{CN})_{2}(\mathrm{CO})_{2}(\mathrm{dmpe})\right] ?(\mathbf{c})$ Sketch the structure of the $\left[\mathrm{Mo}(\mathrm{CN})_{2}(\mathrm{CO})_{2}(\mathrm{dmpe})\right]^{2-}$ ion, including all the possible isomers.

April Berlyoung
April Berlyoung
Numerade Educator
01:30

Problem 74

The square-planar complex $\left[\mathrm{Pt}(\mathrm{en}) \mathrm{Cl}_{2}\right]$ only forms in one of two possible geometric isomers. Which isomer is not observed: cis or trans?

Qiao Ruan
Qiao Ruan
Numerade Educator
02:04

Problem 75

The acetylacetone ion forms very stable complexes with many metallic ions. It acts as a bidentate ligand, coordinating to the metal at two adjacent positions. Suppose that one of the $\mathrm{CH}_{3}$ groups of the ligand is replaced by a $\mathrm{CF}_{3}$ group, as shown here: Sketch all possible isomers for the complex with three tfac ligands on cobalt(II). (You can use the symbol to represent the ligand.)

Arun Bana
Arun Bana
Numerade Educator
01:31

Problem 76

Which transition metal atom is present in each of the following biologically important molecules: (a) hemoglobin, (b) chlorophyls, (c) siderophores, (d) hemocyanine.

Qiao Ruan
Qiao Ruan
Numerade Educator
02:03

Problem 77

Carbon monoxide, CO, is an important ligand in coordination chemistry. When $\mathrm{CO}$ is reacted with nickel metal, the product is $\left[\mathrm{Ni}(\mathrm{CO})_{4}\right],$ which is a toxic, pale yellow liquid. (a) What is the oxidation number for nickel in thiscompound? (b) Given that
$\left[\mathrm{Ni}(\mathrm{CO})_{4}\right]$ is a diamagnetic molecule with a tetrahedral geometry, what is the electron configuration of nickel in this compound? (c) Write the name for $\left[\mathrm{Ni}(\mathrm{CO})_{4}\right]$ using the nomenclature rules for coordination compounds.

Vasu Makani
Vasu Makani
Numerade Educator
05:12

Problem 78

Some metal complexes have a coordination number of $5.$ One such complex is $\mathrm{Fe}(\mathrm{CO})_{5},$ which adopts a trigonal bipyramidal geometry (see Figure 9.8$)$ . (a) Write the name for $\mathrm{Fe}(\mathrm{CO})_{5},$ using the nomenclature rules for coordination compounds. (b) What is the oxidation state of Fe in this compound? (c) Suppose one of the CO ligands is replaced with a $\mathrm{CN}^{-}$ ligand, forming $\left[\mathrm{Fe}(\mathrm{CO})_{4 (\mathrm{CN})\right]^{-}$. How many geometric isomers would you predict this complex could have?

Qiao Ruan
Qiao Ruan
Numerade Educator
00:56

Problem 79

Which of the following objects is chiral: (a) a left shoe, (b) a slice of bread, (c) a wood screw, (d) a molecular model of $\mathrm{Zn}(\mathrm{en}) \mathrm{Cl}_{2},$ (e) a typical golf club?

Rashmi Sinha
Rashmi Sinha
Numerade Educator
02:29

Problem 80

The complexes $\left[\mathrm{V}\left(\mathrm{H}_{2} \mathrm{O}\right)_{6}\right]^{3+}$ and $\left[\mathrm{VF}_{6}\right]^{3-}$ are both known. (a) Draw the $d$ -orbital energy-level diagram for $\mathrm{V}(\mathrm{III})$ octahedral complexes. ( b) What gives rise to the colors of these complexes? (c) Which of the two complexes would you expect to absorb light of higher energy?

Qiao Ruan
Qiao Ruan
Numerade Educator
01:32

Problem 81

One of the more famous species in coordination chemistry is the Creutz-Taube complex: It is named for the two scientists who discovered it and initially studied its properties. The central ligand is pyrazine, a planar six-membered ring with nitrogens at opposite sides. (a) How can you account for the fact that the complex, which has only neutral ligands, has an odd overall charge? (b) The metal is in a low-spin configuration in both cases. Assuming octahedral coordination, draw the $d$-orbital energy-level diagram for each metal. (c) In many experiments the two metal ions appear to be in exactly equivalent states. Can you think of a reason that this might appear to be so, recognizing that electrons move very rapidly compared to nuclei?

Arun Bana
Arun Bana
Numerade Educator
02:41

Problem 82

Solutions of $\left[\mathrm{Co}\left(\mathrm{NH}_{3}\right)_{6}\right]^{2+},\left[\mathrm{Co}\left(\mathrm{H}_{2} \mathrm{O}\right)_{6}\right]^{2+}($ both octahedral $)$ and $\left[\mathrm{CoCl}_{4}\right]^{2-}$ (tetrahedral) are colored. One is pink, one is blue, and one is yellow. Based on the spectrochemical series and remembering that the energy splitting in tetrahedral complexes is normally much less that that in octahedral ones, assign a color to each complex.

Qiao Ruan
Qiao Ruan
Numerade Educator
18:39

Problem 83

Oxyhemoglobin, with an $\mathrm{O}_{2}$ bound to iron, is a low-spin Fe(Il) complex; deoxyhemoglobin, without the O $_{2}$ molecule, is a high-spin complex. (a) Assuming that the coordination environment about the metal is octahedral, how many unpaired electrons are centered on the metal ion in each case? (b) What ligand is coordinated to the iron in place of $\mathrm{O}_{2}$ in deoxyhemoglobin? (c) Explain in a general way why the two forms of hemoglobin have different colors (hemoglobin is red, whereas deoxyhemoglobin has a bluish cast. (d) $\mathrm{A} 15$ -minute exposure to air containing 400 $\mathrm{ppm}$ of CO causes about 10$\%$ of the hemoglobin in the blood to be converted into the carbon monoxide complex, called carboxyhemoglobin. What does this suggest about the relative equilibrium constants for binding of carbon monoxide and $\mathrm{O}_{2}$ to hemoglobin? (e) $\mathrm{CO}$ is a strong-field ligand. What color might you expect carboxyhemoglobin to be?

Susan Hallstrom
Susan Hallstrom
Numerade Educator
05:01

Problem 84

Consider the tetrahedral anions $\mathrm{VO}_{4}^{3-}$ (orthovanadate ion), $\mathrm{CrO}_{4}^{2-}$ (chromate ion), and $\mathrm{MnO}_{4}^{-}$ (permanganate ion). (a) These anions are isoelectronic. What does this statement mean? (b) Would you expect these anions to exhibit $d-d$ transitions? Explain. (c) As mentioned in "A Closer Look" on charge-transfer color, the violet color of MnO $_{4}^{-}$ is due to a ligand-to-metal charge transfer (LMCT) transition. What is meant by this term? (d) The LMCT transition in $\mathrm{MnO}_{4}^{-}$ occurs at a wavelength of 565 $\mathrm{nm} .$ The $\mathrm{CrO}_{4}^{2-}$ ion is yellow. Is the wavelength of the LMCT transition for chromate larger or smaller than that for MnO $_{4}^{-}?$ Explain. (e) The VO $_{4}^{3-}$ ion is colorless. Do you expect the light absorbed by the LMCT to fall in the UV or the IR region of the electromagnetic spectrum? Explain your reasoning.

Qiao Ruan
Qiao Ruan
Numerade Educator
05:37

Problem 85

Given the colors observed for $\mathrm{VO}_{4}^{3-}$ (orthovanadate ion), $\mathrm{CrO}_{4}^{2-}$ (chromate ion), and $\mathrm{MnO}_{4}^{-}$ (permanganate ion (see Exercise $23.84 ),$ what can you say about how the energy separation between the ligand orbitals and the empty $d$ orbitals changes as a function of the oxidation state of the transition metal at the center of the tetrahedral anion?

Susan Hallstrom
Susan Hallstrom
Numerade Educator
02:19

Problem 86

The red color of ruby is due to the presence of $\mathrm{Cr}($ III $)$ ions at octahedral sites in the close-packed oxide lattice of $\mathrm{Al}_{2} \mathrm{O}_{3}$ . Draw the crystal-field splitting diagram for $\mathrm{Cr}($ III $)$ in this environment. Suppose that the ruby crystal is subjected to high pressure. What do you predict for the variation in the wavelength of absorption of the ruby as a function of pressure? Explain.

Qiao Ruan
Qiao Ruan
Numerade Educator
02:03

Problem 87

In 2001 , chemists at SUNY-Stony Brook succeeded in synthesizing the complex trans-$\left[\mathrm{Fe}(\mathrm{CN})_{4}(\mathrm{CO})_{2}\right]^{2-}$, which could be a model of complexes that may have played a role in the origin of life. (a) Sketch the structure of the complex. (b) The complex is isolated as a sodium salt. Write the complete name of this salt. (c) What is the oxidation state of Fein this complex? How many d electrons are associated with the Fe in this complex? (d) Would you expect this complex to be high spin or low spin? Explain.

Arun Bana
Arun Bana
Numerade Educator
01:28

Problem 88

When Alfred Werner was developing the field of coordination chemistry, it was argued by some that the optical activity he observed in the chiral complexes he had prepared was due to the presence of carbon atoms in the molecule. To disprove this argument, Werner synthesized a chiral complex of cobalt that had no carbon atoms in it, and he was able to resolve it into its enantiomers. Design a cobalt(III) complex that would be chiral if it could be synthesized and that contains no carbon atoms. (It may not be possible to synthesize the complex you design, but we will not worry about that for now.)

Qiao Ruan
Qiao Ruan
Numerade Educator
08:33

Problem 89

Generally speaking, for a given metal and ligand, the stability of a coordination compound is greater for the metal in the $+3$ rather than in the $+2$ oxidation state (for metals that form stable $+3$ ions in the first place). Suggest an explanation, keeping in mind the Lewis acid-base nature of the metal-ligand bond.

Arun Bana
Arun Bana
Numerade Educator
02:59

Problem 90

Many trace metal ions exist in the blood complexed with amino acids or small peptides. The anion of the amino acid glycine (gly), can act as a bidentate ligand, coordinating to the metal through nitrogen and oxygen atoms. How many isomers are possible for (a) $\left[\mathrm{Zn}(\mathrm{gly})_{2}\right]$ (tetrahedral), $(\mathbf{b})[\mathrm{Pt}(\mathrm{g}] \mathrm{y})_{2} ]$ (square planar), $(\mathbf{c})\left[\operatorname{Cog}(\mathrm{gly})_{3}\right]($ octahedral)? Sketch all possible isomers. Use the symbol to represent the ligand.

Qiao Ruan
Qiao Ruan
Numerade Educator
05:04

Problem 91

The coordination complex $\left[\mathrm{Cr}(\mathrm{CO})_{6}\right]$ forms colorless, diamagnetic crystals that melt at $90^{\circ} \mathrm{C}$ . (a) What is the oxidation number of chromium in this compound? (b) Given that $\left[\mathrm{Cr}(\mathrm{CO})_{6}\right]$ is diamagnetic, what is the electron configuration of chromium in this compound? (c) Given that $\left[\mathrm{Cr}(\mathrm{CO})_{6}\right]$ is colorless, would you expect CO to be a weak-field or strong-field ligand? (d) Write the name for $\left[\mathrm{Cr}(\mathrm{CO})_{6}\right]$ using the nomenclature rules for coordination compounds.

Susan Hallstrom
Susan Hallstrom
Numerade Educator
12:34

Problem 92

Metallic elements are essential components of many important enzymes operating within our bodies. Carbonic anhydrase, which contains $Z n^{2+}$ in its active site, is responsible for rapidly interconverting dissolved $\mathrm{CO}_{2}$ and bicarbonate ion, HCO $_{3}^{-} .$ The zinc in carbonic anhydrase is tetrahedrally coordinated by three neutral nitrogencontaining groups and a water molecule. The coordinated water molecule has a $\mathrm{pK}_{a}$ of $7.5,$ which is crucial for the enzyme's activity. (a) Draw the active site geometry for the Zn (II) center in carbonic anhydrase, just writing "N" for the three neutral nitrogen ligands from the protein. (b) Compare the $\mathrm{pK}_{a}$ of carbonic anhydrase's active site with that of pure water; which species is more acidic? (c) When the coordinated water to the Zn(II) center in carbonic anhydrase is deprotonated, what ligands are bound to the Zn(II) center? Assume the three nitrogen ligands are unaffected. (d) The $\mathrm{p} K_{a}$ of $\left[\mathrm{Zn}\left(\mathrm{H}_{2} \mathrm{O}\right)_{6}\right]^{2+}$ is $10 .$ Suggest an explanation for the difference between this $\mathrm{pK}_{a}$ and that of carbonic anhydrase. (e) Would you expect carbonic anhydrase to have a deep color, like hemoglobin and other metal-ion-containing proteins do? Explain.

Susan Hallstrom
Susan Hallstrom
Numerade Educator
03:19

Problem 93

Two different compounds have the formulation $\operatorname{coBr}\left(S O_{4}\right) \cdot 5 \mathrm{NH}_{3} .$ Compound $\mathrm{A}$ is dark violet, and compound $\mathrm{B}$ is red-violet. When compound $\mathrm{A}$ is treated with AgNO $_{3}(a q),$ no reaction occurs, whereas compound $\mathrm{B}$ reacts with $\mathrm{AgNO}_{3}(a q)$ to form a white precipitate. When compound $\mathrm{A}$ is treated with $\mathrm{BaCl}_{2}(a q),$ a white precipitate is formed, whereas compound B has no reaction with$\mathrm{BaCl}_{2}(a q) .$ (a) Is $\mathrm{Co}$ in the
same oxidation state in these complexes? (b) Explain the reactivity of compounds $A$ and
B with $A g N O_{3}(a q)$ and $B a C l_{2}(a q) .$ (c) Are compounds $A$ and B isomers of one another? If so, which category from Figure 23.19 best describes the isomerism observed for these complexes? (d) Would compounds A and B be expected to be strong electrolytes, weak electrolytes, or nonelectrolytes?

Arun Bana
Arun Bana
Numerade Educator
04:56

Problem 94

A manganese complex formed from a solution containing potassium bromide and oxalate ion is purified and analyzed. It contains $10.0 \% \mathrm{Mn}, 28.6 \%$ potassium, $8.8\%$ carbon, and 29.2$\%$ bromine by mass. The remainder of the compound is oxygen. An aqueous solution of the complex has about the same electrical conductivity as an equimolar solution of $\mathrm{K}_{4}\left[\mathrm{Fe}(\mathrm{CN})_{6}\right] .$ Write the formula of the compound, using brackets to denote the manganese and its coordination sphere.

Qiao Ruan
Qiao Ruan
Numerade Educator
05:16

Problem 95

The $E^{\circ}$ values for two low-spin iron complexes in acidic solution are as follows:
$\left[\mathrm{Fe}(o-\mathrm{phen})_{3}\right]^{3+}(a q)+\mathrm{e}^{-} \Longrightarrow$
$\quad\quad\quad\quad\quad\quad\quad$ $\left[\mathrm{Fe}(o-\mathrm{phen})_{3}\right]^{2+}(a q) \quad E^{\circ}=1.12 \mathrm{V}$
$\left[\mathrm{Fe}(\mathrm{CN})_{6}\right]^{3-}(a q)+\mathrm{e}^{-} \rightleftharpoons$
$\quad\quad\quad\quad\quad\quad\quad\quad\quad\quad$ $\left[\mathrm{Fe}(\mathrm{CN})_{6}\right]^{4-}(a q) \quad E^{\circ}=0.36 \mathrm{V}$
(a) Is it thermodynamically favorable to reduce both Fe(III) complexes to their Fe(II) analogs? Explain. (b) Which complex, $\left[\mathrm{Fe}(o-\mathrm{phen})_{3}\right]^{3+}$ or $\left[\mathrm{Fe}(\mathrm{CN})_{6}\right]^{3-},$ is more difficult to reduce? (c) Suggest an explanation for your answer to (b).

Arun Bana
Arun Bana
Numerade Educator
03:19

Problem 96

A palladium complex formed from a solution containing bromide ion and pyridine, $\mathrm{C}_{5} \mathrm{H}_{5} \mathrm{N}$ (a good electron-pair donor), is found on elemental analysis to contain 37.6$\%$ bromine, 28.3$\%$ carbon, 6.60$\%$ nitrogen, and 2.37$\%$ hydrogen by mass. The compound is slightly soluble in several organic solvents; its solutions in water or alcohol do not conduct electricity. It is found experimentally to have a zero dipole moment. Write the chemical formula, and indicate its probable structure.

Qiao Ruan
Qiao Ruan
Numerade Educator
02:18

Problem 97

(a) In early studies it was observed that when the complex $\left[\mathrm{Co}\left(\mathrm{NH}_{3}\right)_{4} \mathrm{Br}_{2}\right] \mathrm{Br}$ was placed in water, the electrical conductivity of a 0.05$M$ solution changed from an initial value of 191 $\mathrm{ohm}^{-1}$ to a final value of 374 $\mathrm{ohm}^{-1}$ over a period of an hour or so. Suggest an explanation for the observed results.(See Exercise 23.69 for relevant comparison data.) (b) Write a balanced chemical equation to describe the reaction. (c) $A 500$-mL solution is made up by dissolving 3.87g of the complex. As soon as the solution is formed, and before any change in conductivity has occurred, a 25.00-mL portion of the solution is titrated with 0.0100 $\mathrm{M} \mathrm{AgNO}_{3}$ solution. What volume of AgNO $_{3}$ solution do you expect to be required to precipitate the free $\operatorname{Br}^{-}(a q) ?(\mathbf{d})$ Based on the response you gave to part (b), what volume of $\mathrm{AgNO}_{3}$ solution would be required to titrate a fresh 25.00 -mL sample of $\left[\mathrm{Co}\left(\mathrm{NH}_{3}\right)_{4} \mathrm{Br}_{2}\right] \mathrm{Br}$ after all conductivity changes have occurred?

Arun Bana
Arun Bana
Numerade Educator
04:45

Problem 98

The total concentration of $\mathrm{Ca}^{2+}$ and $\mathrm{Mg}^{2+}$ in a sample of hard water was determined by titrating a 0.100-L sample of the water with a solution of EDTA $^{4-} .$ The EDTA
$^{4-}$ chelatesthe two cations:
$$\begin{array}{c}{\mathrm{Mg}^{2+}+[\mathrm{EDTA}]^{4-} \longrightarrow[\mathrm{Mg}(\mathrm{EDTA})]^{2-}} \\ {\mathrm{Ca}^{2+}+[\mathrm{EDTA}]^{4-} \longrightarrow[\mathrm{Ca}(\mathrm{EDTA})]^{2-}}\end{array}$$
It requires 31.5 $\mathrm{mL}$ of 0.0104 $\mathrm{M}[\mathrm{EDTA}]^{4-}$ solution to reach the end point in the titration. A second 0.100-L sample was then treated with sulfate ion to precipitate $\mathrm{Ca}^{2+}$ as calcium sulfate. The $\mathrm{Mg}^{2+}$ was then titrated with 18.7 $\mathrm{mL}$ of 0.0104 $M[\mathrm{EDTA}]^{4-} .$ Calculate the concentrations of $\mathrm{Mg}^{2+}$ and $\mathrm{Ca}^{2+}$ in the hard water in $\mathrm{mg} / \mathrm{L} .$

Qiao Ruan
Qiao Ruan
Numerade Educator
03:22

Problem 99

Carbon monoxide is toxic because it binds more strongly to the iron in hemoglobin (Hb) than does $\mathrm{O}_{2}$ , as indicated by these approximate standard free-energy changes in blood:
$$\begin{array}{cl}{\mathrm{Hb}+\mathrm{O}_{2} \longrightarrow \mathrm{HbO}_{2}} & {\Delta G^{\circ}=-70 \mathrm{kJ}} \\ {\mathrm{Hb}+\mathrm{CO} \longrightarrow \mathrm{HbCO}} & {\Delta G^{\circ}=-80 \mathrm{kJ}}\end{array}$$
Using these data, estimate the equilibrium constant at 298 K for the equilibrium
$$\mathrm{HbO}_{2}+\mathrm{CO} \rightleftharpoons \mathrm{HbCO}+\mathrm{O}_{2}$$

April Berlyoung
April Berlyoung
Numerade Educator
02:45

Problem 100

The value of $\Delta$ for the $\left[\mathrm{CrF}_{6}\right]^{3-}$ complex is 182 $\mathrm{kJ} / \mathrm{mol}$. Calculate the expected wavelength of the absorption corresponding to promotion of an electron from the lower-energy to the higher-energy $d$-orbital set in this complex. Should the complex absorb in the visible range?

Qiao Ruan
Qiao Ruan
Numerade Educator
01:57

Problem 101

A Cu electrode is immersed in a solution that is 1.00$M$ in $\left[\mathrm{Cu}\left(\mathrm{NH}_{3}\right)_{4}\right]^{2+}$ and 1.00 $\mathrm{M}$ in $\mathrm{NH}_{3} .$ When the cathode is a standard hydrogen electrode, the emf of the cell is found to be $+0.08 \mathrm{V} .$ What is the formation constant for $\left[\mathrm{Cu}\left(\mathrm{NH}_{3}\right)_{4}\right]^{2+} ?$

Arun Bana
Arun Bana
Numerade Educator