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Inorganic Chemistry

Keith F. Purcell, John C. Kotz

Chapter 6

ENERGETICS AND STRUCTURES AS GUIDES TO MAIN - all with Video Answers

Educators

Chapter Questions

05:56

Problem 1

How large must be $K$ for the reaction $\mathrm{A}^{-}+\mathrm{B}^{+} \rightarrow \mathrm{C}^{+}+\mathrm{D}^{-}$if the products are to be contaminated with no more than $0.1 \%$ of each reactant? What value of $\Delta G^{\circ}$ does this condition require? How large a change in $\log K$ is incurred by a change in $\Delta G^{\circ}$ of $1.38 \mathrm{kcal} /$ mole? Reflecting on the influence of "condensation energies," would you say that choice of solvent could be critical to reaction efficiency?

Zaida Minjares
Zaida Minjares
Numerade Educator
03:37

Problem 2

Referring to the reaction in problem 1 , what is the minimum difference in half-cell $E^{\circ}$ s required to meet the product purity criterion?

Rashmi Sinha
Rashmi Sinha
Numerade Educator
04:02

Problem 3

For a reaction $\mathrm{A}+\mathrm{B} \rightarrow \mathrm{C}$, for which $K=10^2 \mathrm{M}^{-1}$, what ratio of $\mathrm{A}_0$ to $\mathrm{B}_0$ is required to produce a product contaminated by no more than $0.1 \%$ of $\mathrm{B}$ ? ( $\mathrm{A}_0$ and $\mathrm{B}_0$ are the initial concentrations of $\mathrm{A}$ and $\mathrm{B}$ ). If $\mathrm{B}_0=1 \mathrm{M}$, what must $\mathrm{A}_0$ be?

Ronald Prasad
Ronald Prasad
Numerade Educator
00:27

Problem 4

Is the reaction exothermic?
$$
\mathrm{R}_3 \mathrm{P}=\mathrm{O}+\mathrm{Si}_2 \mathrm{Cl}_6 \rightarrow \mathrm{R}_3 \mathrm{P}+\left(\mathrm{Cl}_3 \mathrm{Si}_2\right) \mathrm{O}
$$

Aadit Sharma
Aadit Sharma
Numerade Educator
02:11

Problem 5

Do you suppose that the thermochemical bond energies in Table 6-3 are larger or smaller than simple homolytic dissociation energies? Why? (You may find it helpful to re-read the bond energy section of Chapter 3.)

Susan Hallstrom
Susan Hallstrom
Numerade Educator
01:31

Problem 6

With reference to Figure 6-1, predict whether
or
$$
\begin{aligned}
& >\mathrm{B}-\mathrm{F}+\mathrm{HOR} \rightarrow \geq \mathrm{BOR}+\mathrm{HF} \\
& \geq \mathrm{B}-\mathrm{Cl}+\mathrm{HOR} \rightarrow \geq \mathrm{BOR}+\mathrm{HCl}
\end{aligned}
$$
is more exothermic. To what do you ascribe the greater driving force in your choice?

Narayan Hari
Narayan Hari
Numerade Educator
03:19

Problem 7

Would
$$
\mathrm{S}_2 \mathrm{Cl}_2+2 \mathrm{H}_2 \mathrm{~S}_{\mathrm{n}} \rightarrow \mathrm{H}_2 \mathrm{~S}_{2 \mathrm{n}+2}+2 \mathrm{HCl}
$$
be a reasonable (from a thermodynamic view) scheme for synthesizing sulfanes?

Christopher Nilsen
Christopher Nilsen
Numerade Educator
01:03

Problem 8

Is the reaction
$$
\mathrm{R}_8 \mathrm{SiOR}+\mathrm{BX}_3 \rightarrow \mathrm{R}_3 \mathrm{SiX}+\mathrm{BX}_2(\mathrm{OR})
$$
a potentially useful way to convert a silyl ether to a silyl fluoride or chloride?

Aadit Sharma
Aadit Sharma
Numerade Educator
04:52

Problem 9

How would entropy factors and solvent polarity affect scrambling reactions like
$$
\mathrm{BX}_3+\mathrm{BY}_3 \rightleftarrows \mathrm{BX}_2 \mathrm{Y}+\mathrm{BY}_2 \mathrm{X} \quad \text { ? }
$$

Rashmi Sinha
Rashmi Sinha
Numerade Educator
02:42

Problem 10

Using the expression
$$
E=e^2 q_{+} q_{-} / d+B / d^2
$$
for a single ion pair, determine how $d_0$ depends on $q_* q_2$, and $B$. What is the effect of ion charge on the value of $d_0$ ? Assuming $n$ to be the same for $\mathrm{NaF}$ and $\mathrm{MgO}$ (both cations and anions have the same inert gas configuration), what is the ratio $d_0(\mathrm{NaF}) / d_0(\mathrm{MgO})$ ?

Dominador Tan
Dominador Tan
Numerade Educator
04:10

Problem 11

Assuming that the $\mathrm{Na}^{+}$and $\mathrm{F}^{-}$ions are just in contact in $\mathrm{NaF}$ and knowing that $d_0=2.31$ A, calculate the radii of $\mathrm{Na}^{+}$and $\mathrm{F}^{-}$from Slater's effective nuclear charges (Chapter 1), where $r=$ const./ $Z^*$.

William Mills
William Mills
Numerade Educator
02:37

Problem 12

Using the Born equation as a basis for your answer, to what can you attribute the facts that $\mathrm{MgO}$ is much harder, higher melting, and less soluble in $\mathrm{H}_2 \mathrm{O}$ than $\mathrm{NaF}$ (they both exhibit the same crystal structure)?

Pronoy Sinha
Pronoy Sinha
Numerade Educator
01:45

Problem 13

What plane through a face-centered cubic unit cell contains the largest number of ion nuclei? How many nuclei are in that plane?

Dr. Satish Ingale
Dr. Satish Ingale
Numerade Educator
01:10

Problem 14

How many formula weights of $\mathrm{MX}_2$ occur in the unit cell of the rutile structure? What is the coordination number of each cation and anion?

Adriano Chikande
Adriano Chikande
Numerade Educator
03:20

Problem 15

What is the ratio $r_h / r_l$ for the triangular holes in a layer of close packed ions? Were such a structure (with all trigonal holes filled) found for a compound, what would be its empirical formula? Taking the lattice ion to be $\mathrm{O}^{2-}$, are there any cations (except $\mathrm{H}^{+}$) small enough to fit in the trigonal holes?

Lottie Adams
Lottie Adams
Numerade Educator
01:47

Problem 16

Calculate the volume of the unit cell of $\mathrm{KCl}$ and then the density of the salt (experimental value $=1.98 \mathrm{~g} / \mathrm{cm}^3$ ).

Keshav Singh
Keshav Singh
Numerade Educator
03:16

Problem 17

Which of the ionic structure types $(\mathrm{CsCl}$ or $\mathrm{NaCl})$ is favored for a given compound $\mathrm{MX}$ if severe pressure is exerted on the crystal?
18. When the cation in the anion lattice holes is smaller than the hole, will the lattice energy be different from that predicted by the Born equation? How and why?

Khalida Dawar
Khalida Dawar
Numerade Educator
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Problem 19

A simple binary compound, $\mathrm{M}_{\mathrm{m}} \mathrm{X}_{\mathrm{n}}$, is known to have a structure of ecp anions with all $T_d$ holes filled with $\mathrm{M}$ cations. What is the empirical formula of the compound?

Susan Hallstrom
Susan Hallstrom
Numerade Educator
View

Problem 20

Use the following data (in $\mathrm{kcal} / \mathrm{mole}$ ) to calculate the electron affinity of $\mathrm{Cl}$.
$$
\begin{array}{lrcccc}
& \Delta H_i & \Delta H_{\text {sub }}^{\mathrm{M}} & I_{\mathrm{M}} & D_{\mathrm{Cl}_2} & \text { shortest inter-ion distance } \\
\hline \mathrm{NaCl} & 98.3 & 25.9 & 5.14 & 57.8 & 2.81 \mathrm{~A} \\
\mathrm{KCl} & 104.4 & 19.8 & 4.34 & & 3.14 \mathrm{~A} \\
\hline
\end{array}
$$

Vipin Singh
Vipin Singh
Numerade Educator
07:08

Problem 21

Which would you predict would have higher solid state ionic conductivity, a salt MX with the $\mathrm{NaCl}$ structure or a salt $\mathrm{MX}$ with the zinc blende structure?

Kevin Zaborsky
Kevin Zaborsky
Numerade Educator

Problem 22

The solid $\mathrm{Ag}_2 \mathrm{HgI}_4$ (yellow) consists of cubic close packed $\mathrm{I}^{-}$with $\mathrm{Ag}^{+}$and $\mathrm{Hg}^{2+}$ ions in tetrahedral holes. Are there sufficient cations to occupy all the $T_4$ holes? In the range from $40^{\circ}$ to $50^{\circ} \mathrm{C}$, the color changes to red and the conductivity increases to a value $\sim 1000$ times greater than normal for an ionic solid at $50^{\circ}$, yet the anion lattice remains cubic close packed. What do you suppose happens within the crystal in the $40^{\circ}-50^{\circ}$ range?

Check back soon!
01:21

Problem 23

Describe predicted structural types for $\mathrm{AlP}_2, \mathrm{FeCl}_3, \mathrm{NaH}_2, \mathrm{MnF}, \mathrm{Cul}, \mathrm{NaBH}$, and TICl.

Shazia Naz
Shazia Naz
Numerade Educator
03:16

Problem 24

Both $\mathrm{FeCl}_2$ and $\mathrm{FeCl}_3$ have layer structures based on close-packed anions. How do their structures differ? Aside from the anions, in what sense are their structures alike? Make sketches like those of Figure 6-4 to illustrate your points.

Khalida Dawar
Khalida Dawar
Numerade Educator
02:52

Problem 25

Which salt in each pair do you expect to show the larger deviation from the ideal ionic behavior?
$$
\begin{array}{lll}
\mathrm{CaCl}_2 / \mathrm{ZnCl}_2 & \mathrm{MgF}_2 / \mathrm{TiO}_2 & \mathrm{MgCl}_2 / \mathrm{BeCl}_2 \\
\mathrm{CdCl}_2 / \mathrm{CdI}_2 & \mathrm{Al}_2 \mathrm{O}_3 / \mathrm{Ga}_2 \mathrm{O}_3 & \\
\mathrm{ZnO} / \mathrm{ZnS} & \mathrm{CaCl}_2 / \mathrm{CdCl}_2
\end{array}
$$

Adriano Chikande
Adriano Chikande
Numerade Educator
00:43

Problem 26

Make a sketch, like those of Figure 6-4, for $\mathrm{CrCl}_3$ (each $\mathrm{Cr}^{3+}$ has a $\mathrm{C} . \mathrm{N}$. $=6$, each $\mathrm{Cl}^{-}$ has a C.N. = 2).

Aadit Sharma
Aadit Sharma
Numerade Educator
01:01

Problem 27

Account for the observed trends in $\Delta H$; of the following series (use a Haber cycle to identify critically important influences on $\Delta H_i^{\circ}$ ). Remember that $\Delta H_i^{;}<0$.
a) $\mathrm{NaF}<\mathrm{NaCl}<\mathrm{NaBr}<\mathrm{NaI}$
b) $\mathrm{LiF}<\mathrm{NaF}<\mathrm{KF}<\mathrm{RbF}$
c) Lil $>\mathrm{NaI}>\mathrm{KI}>\mathrm{Rbl}>\mathrm{CsI}$

Narayan Hari
Narayan Hari
Numerade Educator
01:01

Problem 28

Why can $\mathrm{BPh}_4^{-}$be used to determine $\mathrm{K}^{+}$gravimetrically in aqueous solution, while $\mathrm{ClO}_4^{-}$ cannot (the anions are very nearly the same size)?

Narayan Hari
Narayan Hari
Numerade Educator
02:42

Problem 29

Suggest reasons why $\mathrm{MClO}_4$ salts $(\mathrm{M}=$ alkali metal) exhibit a minimum in aqueous solubility at $\mathrm{M}=\mathrm{Rb}^{+}$.

Shahina -
Shahina -
Numerade Educator
04:40

Problem 30

Consider the body centered unit cell for metals (all atoms of like size, in contact along the body diagonal). Find the unit cell volume as a function of $r$, the atom radius. What is the packing efficiency (the fraction of the unit cell volume actually occupied by atoms)? Is the body centered structure more or less efficient than the face centered geometry?

Nicole Smina
Nicole Smina
Numerade Educator
02:41

Problem 31

Do you expect GaAs to be an ionic solid? What do you expect would happen to the electrical conductivity of GaAs if Se were added? If Ga were added? If a crystal of GaAs is doped with $\mathrm{Se}$ at one end and with Ga at the other, in which direction would electric current (electrons) flow more readily? Would you anticipate greater or less discrimination in direction of electron flow from such an extrinsic semiconductor, compared to one doped at one end only?

Marissa Turner
Marissa Turner
Numerade Educator
02:26

Problem 32

The "closo" borane anion $(\mathrm{BH})_{12}^2$ has an icosohedral structure. From a valence electron point of view, does it seem reasonable to you that the carborane $\mathrm{B}_{10} \mathrm{C}_2 \mathrm{H}_{12}$ exists? of the three geometric isomers $[(1,2)$. $(1,7)$, and $(1,12)]$ possible for the carborane, two may be readily interconverted at $450^{\circ} \mathrm{C}$. Starting with the icosohedron below, discover which pair $[(1.2 \rightleftharpoons 1.7) .(1.2 \rightleftharpoons 1.12)$ or $(1.7 \rightleftharpoons 1.12)]$ are interconverted simply by expansion of the icosohedron into a cuboctahedron and then relaxation back to an icosohedron.
figure cant copy

Adriano Chikande
Adriano Chikande
Numerade Educator
05:16

Problem 33

Knowing that $\mathrm{B}_2 \mathrm{H}_6$ and $\mathrm{BH}_4^{-}$hydrolyze in aqueous acid, why do you suppose $85 \% \mathrm{H}_3 \mathrm{PO}_4$ (1:1 mole ratio $\mathrm{H}_2 \mathrm{O} / \mathrm{H}_3 \mathrm{PO}_4$ ) can be used in the synthesis of diborane? What is the likely experimental arrangement and order of mixing of the reagents in this synthesis?

Jennifer Hudspeth
Jennifer Hudspeth
Numerade Educator
01:13

Problem 34

Knowing that $\mathrm{Al}_2 \mathrm{Cl}_7$ has a $\mathrm{C}_{3 \pm}$ geometry, what do you conclude about the $\mathrm{Al}-\mathrm{Cl}-\mathrm{Al}$ angle? Is this expected for the central $\mathrm{Cl}^{-}$sharing only two electron pairs with the two $\mathrm{Al}$ ions? Suggest a feature of the $\mathrm{Al}-\mathrm{Cl}-\mathrm{Al}$ bonding to account for that angle.

Anand Jangid
Anand Jangid
Numerade Educator
04:24

Problem 35

Propose single step syntheses of $\mathrm{B}(\mathrm{OR})_3$ starting with a boron hydride, a boron halide, and a boron oxide.

Himanshu Kushwaha
Himanshu Kushwaha
Numerade Educator
01:09

Problem 36

By analogy with carbon allotropes, suggest two structures for boron nitride, $(\mathrm{BN})_x$ =

Matthew Confer
Matthew Confer
Numerade Educator
03:37

Problem 37

Compare the thermal yields of
and
$$
\begin{aligned}
& \mathrm{CH}_{4(\xi)}+\mathrm{O}_{2(k)} \rightarrow \mathrm{CO}_{2(\xi)}+\mathrm{H}_2 \mathrm{O}_{(k)} \\
& \mathrm{B}_2 \mathrm{H}_{\text {(k) }}+\mathrm{O}_{2(k)} \rightarrow \mathrm{B}_2 \mathrm{O}_{3(\xi)}+\mathrm{H}_2 \mathrm{O}_{(k)}
\end{aligned}
$$
on the basis of $\mathrm{kcal} /\left(\mathrm{g}\right.$ hydride). Would use of $\mathrm{B}_2 \mathrm{H}_6$ as a substitute for natural gas be practical? (What are the physical properties of the products?)

Adriano Chikande
Adriano Chikande
Numerade Educator
05:29

Problem 38

Predict products for the following reactions.
a) $2 \mathrm{NaBH}_4+2 \mathrm{I}_2 \rightarrow 2 \mathrm{NaI}+$ ?
(reducing (oxidizing
Lewis base) Lewis acid)
b) $\mathrm{B}_2 \mathrm{Cl}_4+\mathrm{C}_2 \mathrm{H}_4 \rightarrow$ ? (intermediate species from $\pi$ acid/base concept)
c) $3 \mathrm{Me}_2 \mathrm{PH}+\frac{3}{2} \mathrm{~B}_2 \mathrm{H}_6 \underset{2}{ } \mathrm{H}_2+$ ?
d) $\mathrm{R}_2 \mathrm{BH}+\mathrm{C}_2 \mathrm{H}_4 \underset{3}{ }$ ? (consider the HOMO and LUMO of both reagents)
e) the product from (d) $+\mathrm{H}_2 \mathrm{O} \xrightarrow{\mathrm{H}^{+}} \mathrm{C}_2 \mathrm{H}_6+$ ?

Colton K
Colton K
Numerade Educator

Problem 39

Why do you think the order and rate of mixing of $\mathrm{H}_2 \mathrm{SO}_4$ and $\mathrm{LiAlH}_4$ /THF is important to the preparation of $\mathrm{AlH}_3$ ?

Check back soon!
03:44

Problem 40

Why do you suppose $\mathrm{HCl}$ is an effective choice of solvent for the reaction
$$
\mathrm{CH}_3 \mathrm{COCl}+\mathrm{Al}_2 \mathrm{Cl}_8 \rightarrow\left[\mathrm{CH}_3 \mathrm{CO}\right]\left[\mathrm{Al}_2 \mathrm{Cl}_7\right] ?
$$

Nicholas Sacco
Nicholas Sacco
Numerade Educator
03:46

Problem 41

Predict products for the following reactions.
a) $\mathrm{LiAlH}_4+4 \mathrm{RCHCH}_2 \rightarrow$ ? (a Li+ salt of 4-coordinate Al; related to question 38(d))
b) $\mathrm{LiAlH}_4+\mathrm{Me}_3 \mathrm{NH}^{+} \mathrm{Cl}^{-} \rightarrow \mathrm{H}_2+$ ?
c) $\mathrm{LiAlH}_4+4 \mathrm{ROH} \rightarrow 2 \mathrm{H}_2+$ ?
d) $4 \mathrm{LiH}+\mathrm{AlCl}_3 \xrightarrow[\mathrm{El}_2 \mathrm{O}]{ } 3 \mathrm{LiCl}+$ ?
e) $\mathrm{Al}_2 \mathrm{X}_6+\mathrm{Al}_2 \mathrm{R}_6 \rightarrow$ ? (product has bridging $\mathrm{X}$ )
CARBON AND SILICON
$$
\begin{aligned}
&\text { Bond Energies for Reference }\\
&\begin{array}{rrrr}
\hline \mathrm{Si}=\mathrm{Si} & 76 & \mathrm{C} \equiv \mathrm{C} & 200 \\
\mathrm{Si}-\mathrm{Si} & 54 & \mathrm{C}=\mathrm{C} & 146 \\
\mathrm{Si}-\mathrm{H} & 76 & \mathrm{C}-\mathrm{C} & 83 \\
\mathrm{Si}-\mathrm{C} & 73 & \mathrm{C}-\mathrm{H} & 99 \\
\mathrm{Si}-\mathrm{O} & 111 & \mathrm{C}-\mathrm{O} & 86 \\
\mathrm{Si}-\mathrm{F} & 143 & \mathrm{C}-\mathrm{F} & 117 \\
\mathrm{Si}-\mathrm{Cl} & 96 & \mathrm{C}-\mathrm{Cl} & 78 \\
\hline
\end{array}
\end{aligned}
$$

Susan Hallstrom
Susan Hallstrom
Numerade Educator
01:28

Problem 42

Recall or look up the structure of graphite and predict the $\mathrm{C}-\mathrm{C}$ bond order. Does your result fit with the fact that the $\mathrm{C}-\mathrm{C}$ distance in graphite is a little greater than that in benzene?

Lottie Adams
Lottie Adams
Numerade Educator
01:28

Problem 43

Is the fluorination of graphite to produce poly(carbon fluoride) exothermic?
$$
(C)_n+\frac{n}{2} \mathrm{~F}_2 \rightarrow(C F)_n
$$
Which compound, graphite or $(\mathrm{CF})_n$, should be more stable to air oxidation to $\mathrm{CO}_2$ ? To be of advantage as a substitute for graphite lubricant. (CF) must have what structural characteristic? Knowing that the hexagons of (CF), have a "boat" structure, make a sketch of several fused "boats" (show the CF bonds, too) so as to compare the lamellar structure directly with that of graphite.

Lottie Adams
Lottie Adams
Numerade Educator
02:50

Problem 44

The simpler metal carbides are of three types with distinctly different hydrolytic behavior:
$$
\begin{aligned}
& \mathrm{Be}_2 \mathrm{C} \text { or } \mathrm{Al}_4 \mathrm{C}_2 \xrightarrow{\mathrm{H}_2 \mathrm{O}} \mathrm{CH}_4+\text { metal hydroxide } \\
& \mathrm{Na}_2 \mathrm{C}_2 \text { or } \mathrm{CaC}_2 \xrightarrow{\mathrm{H}_2 \mathrm{O}} \mathrm{C}_2 \mathrm{H}_2+\text { metal hydroxide } \\
& \mathrm{Mg}_2 \mathrm{C}_3 \xrightarrow{\mathrm{H}_2 \mathrm{O}} \mathrm{C}_3 \mathrm{H}_4+\mathrm{Mg}(\mathrm{OH})_2 \\
& \mathrm{SiC} \xrightarrow{\mathrm{H}_3 \mathrm{O}} \text { inert }
\end{aligned}
$$

Characterize each of these as covalent or ionic; in the latter eases, infer a structure for the carbon anion present. Carborundum (SiC) is an extremely hard material used as an abrasive. Identify a sketch in this chapter that describes its structure.

Susan Hallstrom
Susan Hallstrom
Numerade Educator
05:19

Problem 45

Construct $\pi$ mo diagrams for the linear molecules $\mathrm{C}, \mathrm{O}_2$ for $n=1,3,5$ and for $n=2,4$. Which set yields free radicals? What is their spin multiplicity? Only one of these sets ( $n$ even or odd) is known; which is it?

Emerson G
Emerson G
Numerade Educator
03:40

Problem 46

Cyanogen. $(\mathrm{CN})_2$, is a flammable gas. Although it is generally stable, impurities can cause its polymerization to solid paracyanogen, $(\mathrm{CN})_z$, at high temperature. Estimate the exothermicity of this reaction, using $E_{\mathrm{cev}}=212 \mathrm{kcal} / \mathrm{mole}, E_{\mathrm{C}=\mathrm{V}}=147 \mathrm{kcal} / \mathrm{mole}$, and $E_{\mathrm{C}-\mathrm{N}}=73 \mathrm{kcal} / \mathrm{mole}$.
figure cant copy
Is your estimate in the range where-the energy of $(\mathrm{CN})_{\text {ses }} \rightarrow(\mathrm{CN})_{\text {res }}$ and the overall entropy change might seriously affect $\Delta G^{\circ}$ ?

Ronald Prasad
Ronald Prasad
Numerade Educator
02:56

Problem 47

Liquid HCN is dangerously unstable with respect to trimer formation. Propose a structure for the trimer and estimate the energy of the trimerization reaction. (See the preceding problem for bond energy values.) What all-carbon and boron/nitrogen compounds exhibit related structures?

Kim Trang Nguyen
Kim Trang Nguyen
Numerade Educator
01:43

Problem 48

Account for the large $\mathrm{Si}-\mathrm{O}-\mathrm{Si}$ angle of $\sim 150^{\circ}$ in $\left(\mathrm{H}_3 \mathrm{Si}\right)_2 \mathrm{O}$.

Hitendra Singh
Hitendra Singh
Numerade Educator
02:29

Problem 49

Is it surprising to you to learn that $\mathrm{Me}_3 \mathrm{SiOH}$ is as good a hydrogen-bonding acid as $t$-BuOH? If so, why and how can you rationalize this finding? If not, why not? Du yuu expect a large $\mathrm{Si}-\mathrm{O}-\mathrm{H}$ angle?

Lottie Adams
Lottie Adams
Numerade Educator
02:04

Problem 50

$\mathrm{Ph}_3 \mathrm{SiX}$ reacts with bipyridine figure cant copy to form an ionic solid of formula $\mathrm{Ph}_3 \mathrm{SiX}$ - bipy. Propose a geometry for the silicon cation; note and comment on any unusual aspect regarding the positions of the carbon and nitrogen atoms about silicon.

Lottie Adams
Lottie Adams
Numerade Educator
02:04

Problem 51

Propose a structure for dimeric bus(trimethylsilyl)amide, $\left(\mathrm{Me}_3 \mathrm{Si}_2 \mathrm{~N}^{-}\right.$, and comment on any "unusual" aspect of the disposition of $\mathrm{C}$ and $\mathrm{N}$ about $\mathrm{Si}$.

Lottie Adams
Lottie Adams
Numerade Educator
00:43

Problem 52

Predict products for
a) $\mathrm{X}_3 \mathrm{SiH}+\mathrm{C}_2 \mathrm{H}_4 \xrightarrow[\text { (metal catyst1 }]{ }$ (see problems $6-38,6-41$ )
b) $2 \mathrm{SiF}_{(4)}+\mathrm{H}_2 \mathrm{O}_{(\mathrm{k})} \rightarrow$

Grigoriy Sereda
Grigoriy Sereda
Numerade Educator
02:28

Problem 53

Which silicate anion structure most resembles those of $\mathrm{B}_2 \mathrm{O}_3$ and $(\mathrm{CF})_n$ ? Does it have the expected shear properties?

Kim Trang Nguyen
Kim Trang Nguyen
Numerade Educator
02:14

Problem 54

What are the point groups for $\left(\mathrm{SiO}_3^{2-}\right)_3$ and $\left(\mathrm{SiO}_3^{2-}\right)_6$ ?

Dominador Tan
Dominador Tan
Numerade Educator
06:08

Problem 55

Make a "bed-spring" sketch of hypothetical racemic quartz (i.e., similar to 22). With silicon ions at the points of tangency, satisfy yourself that the silicon is in a planar environment of four oxygens in racemic quartz, whereas coils of like symmetry produce a tetrahedral environment for silicon.

Crystal Wang
Crystal Wang
Numerade Educator
01:49

Problem 56

Using an $\mathrm{Si}-\mathrm{O}_6$ distance of $1.7 \mathrm{~A}$ and an $\mathrm{Si}-\mathrm{O}_6-\mathrm{Si}$ angle of $140^{\circ}$ in $\left(\mathrm{SiO}_3^{2-}\right)_6$, calculate the distance between nearest silicon atoms. How big (diameter) is the "bowl" of the hexamer? Does this seem large enough to pass an $\mathrm{O}_2$ molecule $(\sim 1.2 \times 1.4 \mathrm{~A})$ ?

Narayan Hari
Narayan Hari
Numerade Educator
02:32

Problem 57

Using resonance structures and bond order arguments, comment on the less hazardous nature of $\mathrm{NaN}_3$ than of $\mathrm{HN}_3$, with respect to decomposition to produce $\mathrm{N}_2$. Does knowing that $r_{\mathrm{NN}}=1.16 \AA$ in $\mathrm{N}_3^{-}$and $1.24 \AA, 1.13 \AA$ in $\mathrm{HN}_3$ relate to your theoretical arguments?
Which in each pair is more likely to detonate?
$$
\begin{aligned}
& \mathrm{RbN}_3, \mathrm{AgN}_3 \\
& \mathrm{Hg}_3\left(\mathrm{~N}_3\right)_2, \mathrm{Ba}\left(\mathrm{N}_3\right)_2 \\
& \mathrm{KN}_3, \mathrm{CuN}
\end{aligned}
$$

Freddie Montague
Freddie Montague
Numerade Educator
04:08

Problem 58

The problem of chemical conversion (nitrogen "fixation") of $\mathrm{N}_2$ to $\mathrm{NH}_3$ is a significant one that illustrates the importance of thermodynamic concepts. Consider the relative ease of the steps Which step is most costly (in terms of energy), and which of the species $\mathrm{N}_2, \mathrm{~N}_2 \mathrm{H}_2$, or $\mathrm{N}_2 \mathrm{H}_4$ therefore requires the greatest chemical activation (either by extreme temperature conditions or by catalytic combination) so as to weaken the NN link? The first three species exhibit a lone pair on each nitrogen. How does the Ip/Ip repulsion increase for $\mathrm{N}_2 \rightarrow \mathrm{N}_2 \mathrm{H}_2$ compare with that of $\mathrm{N}_2 \mathrm{H}_2 \rightarrow \mathrm{N}_2 \mathrm{H}_4$ ?

Anatole Borisov
Anatole Borisov
Numerade Educator
02:04

Problem 59

Which compound, $\mathrm{NF}_3$ or $\mathrm{NCl}_3$, is more unstable with respect to reversion to the elements? Are both unstable in this sense? Which presents the greater hazard in handling?

Nicole Smina
Nicole Smina
Numerade Educator
05:16

Problem 60

Were you to attempt synthesis of $\mathrm{N}(\mathrm{OH})_3$, what decomposition pathways might you have to guard against? Consider only known, "stable" oxides and oxyacids of nitrogen as possible products, tiz.,
$$
\mathrm{N}(\mathrm{OH})_3 \rightarrow \mathrm{HNO}_2+\mathrm{H}_2 \mathrm{O}
$$

Arjun Tibrewal
Arjun Tibrewal
Numerade Educator
01:28

Problem 61

How might you explain why the fumes generated by $\mathrm{HNO}_3$ oxidation of $\mathrm{Cu}$ are colorless for a few millimeters above the solution surface, but brown thereafter?

Crystal Wang
Crystal Wang
Numerade Educator
00:54

Problem 62

With regard to the structure of $\mathrm{N}_2 \mathrm{O}_{\mathrm{Sg} \text {. }}$ would a linear $\mathrm{N}-\mathrm{O}-\mathrm{N}$ geometry favor a $D_{2 k}$ or $D_{24}$ (twisted $\mathrm{NO}_2$ groups) structure?

Alkendra Singh
Alkendra Singh
Numerade Educator
01:47

Problem 63

Is nitric oxide thermodynamically stable with respect to nitrous oxide and nitrogen dioxide?

Ajay Singhal
Ajay Singhal
Numerade Educator
01:56

Problem 64

Using the approach of Chapter 4, develop an mo diagram applicable to $\mathrm{NO}_2$ and $\mathrm{NF}_2$. Identify the HOMO in each case so as to predict whether the radicals are $\sigma$ or $\pi$ in nature.

CG
Chirag Gupta
Numerade Educator
03:35

Problem 65

Following the idea of association of $\mathrm{NO}_2$ and $\mathrm{NO}$ radicals by HOMO overlap, extract from the text the $\mathrm{N}-\mathrm{N}$ bond dissociation energies of $\mathrm{N}_2 \mathrm{O}_4, \mathrm{~N}_2 \mathrm{O}_3$, and $\mathrm{N}_2 \mathrm{O}_2$ and correlate their order with the variation in HOMO-HOMO overlaps.

Prachita Kush
Prachita Kush
Numerade Educator
02:29

Problem 66

Sketch the LUMO of $\mathrm{NO}_2^*$ and account for the structure of $\mathrm{XNO}_2$ in terms of attack by $\mathrm{X}^{-}$upon $\mathrm{NO}_2^{+}$(what is there about the LUMO that renders its amplitude at $\mathrm{N}$ larger than at $\mathrm{O}^?$ ).

Adriano Chikande
Adriano Chikande
Numerade Educator
01:13

Problem 67

With reference to the parenthetical comment on p. 337 regarding the $\mathrm{O}-\mathrm{H}$, rather than $\mathrm{N}-\mathrm{H}$, bond in $\mathrm{HNO}_2$, argue that an $\mathrm{F}-\mathrm{N}$, rather than $\mathrm{F}-\mathrm{O}$, bond is preferred in $\mathrm{FNO}_2$

Sam Limsuwannarot
Sam Limsuwannarot
Numerade Educator
00:55

Problem 68

Since there is no difference in the number of $\mathrm{P}$-P bonds per phosphorus atom in the white and black allotropes, why is the former so much more (a) volatile and (b) reactive than the latter?

Mishal Gul
Mishal Gul
Numerade Educator
01:13

Problem 69

With regard to the NO a bond strength as a function of nitrogen hybrid $s$ character, how do the fluorines of $\mathrm{F}_3 \mathrm{NO}$ affect the $\mathrm{NO}$ bond strength relative to organic amine oxides? (Consult the section on proton affinities in Chapter 5 before answering.)

Sam Limsuwannarot
Sam Limsuwannarot
Numerade Educator
03:10

Problem 70

Estimate the enthalpy of
$$
2 \mathrm{P}_2 \mathrm{R}_2 \rightarrow(\mathrm{PR})_4
$$
in order to identify whether the cyclophosphine may be produced during attempts to synthesize compounds containing $-\mathrm{P}=\mathrm{P}-$.

Tracy Tourville
Tracy Tourville
Numerade Educator
00:40

Problem 71

While $\mathrm{PF}_5$ is a colorless gas, $\mathrm{PCl}_5$ is a white solid, often described as having a pale green-yellow tinge to it. $\mathrm{PCl}_3$ is a colorless liquid (b.p. $76^{\circ}$ ). Account for the "greenyellow" tinge to $\mathrm{PCl}_5$ and infer from this some ideas about the strengths of bonds in $\mathrm{PCl}_5$.

Hunza Gilgit
Hunza Gilgit
Numerade Educator
02:37

Problem 72

Diphosphine, a pyrophoric volatile liquid, is photosensitive, yielding $P_4$ and phosphine
$$
3 \mathrm{P}_2 \mathrm{H}_4 \xrightarrow{A} 4 \mathrm{PH}_3+\frac{1}{2} \mathrm{P}_4
$$

Argue that this reaction is approximately thermally "neutral" ( $\Delta E \approx 0)$ but free-energy spontaneous.

Himanshu Kushwaha
Himanshu Kushwaha
Numerade Educator
03:19

Problem 73

Draw resonance structures for $\mathrm{HPO}_3$ (obtained from thermal dehydration of $\mathrm{H}_3 \mathrm{PO}_4$ at $\geq 300^{\circ}$ ) and the conjugate base $\mathrm{PO}_3^{-}$. Comment on the anion structure of $\mathrm{Na}_3 \mathrm{P}_3 \mathrm{O}_9$ in relation to that of monomeric $\mathrm{BO}_3^{3-}$ salts.

Nadir Iqbal
Nadir Iqbal
Numerade Educator
05:04

Problem 74

Compare the approximate energies for
$$
\begin{aligned}
& \mathrm{O}_2 \mathrm{~F}_2 \rightarrow \mathrm{O}_2+\mathrm{F}_2 \\
& \mathrm{~S}_2 \mathrm{~F}_2 \rightarrow \frac{1}{4} \mathrm{~S}_8+\mathrm{F}_2
\end{aligned}
$$

Is a distinction to be made in the care with which the difluorides must be handled? Which of the two difluorides is potentially more useful for selective fluorination reactions?

Iryna Ivaniuk
Iryna Ivaniuk
Numerade Educator
02:57

Problem 75

Generalize in equation form the energy of
$$
\mathrm{XO}_2 \mathrm{X} \rightarrow \mathrm{XO}_2 \mathrm{X}+\frac{n-2}{2} \mathrm{O}_2
$$

What is the prognosis for preparation of polyoxide materials?

Lottie Adams
Lottie Adams
Numerade Educator
03:03

Problem 76

Would decomposition of $\mathrm{RO}_2 \mathrm{H}$ more likely produce $\left(\mathrm{RH}+\mathrm{O}_2\right)$ or $\left(\mathrm{ROH}+\frac{1}{2} \mathrm{O}_2\right)$ ?

Banhishikha Sinha
Banhishikha Sinha
Numerade Educator
05:04

Problem 77

Comment on the order of thermochemical bond energies $E_{0-0}<E_{0-F}$ with respect to $\mathrm{Ip} / \mathrm{lp}$ repulsions, $\sigma$ bond strengths, and atom relaxation energies (for the latter you may wish to consult the section on bond energies in Chapter 3).

Brandy Heflin
Brandy Heflin
Numerade Educator

Problem 78

Why should $\mathrm{S}_8^{2+}$ prefer the bicyclo(3.3) rather than bicyclo(1.5) or bicyclo(2.4) structures?

Check back soon!
03:14

Problem 79

a) Use Pauling's defined relation between bond energy and atom electronegativity to estimate $E_{\mathrm{s}-\mathrm{Br}}$ and $E_{\mathrm{s}-1}$.
$$
\Delta x=\frac{1}{23}\left[E_{\mathrm{s}-\mathrm{x}}-\left(E_{\mathrm{S}-5} \cdot E_{\mathrm{x}-\mathrm{x}}\right)^{1 / 2}\right]
$$

From these, estimate the enthalpy change for
$$
\frac{1}{8} \mathrm{~S}_{8(k)}+\mathrm{X}_{2(k)} \rightarrow \mathrm{SX}_{2(k)}
$$
Finally, might condensation energies and entropy changes be important enough to affect your decision to attempt synthesis of $\mathrm{SBr}_2$ or $\mathrm{SI}_2$ ?
b) Were you to attempt synthesis of $\mathrm{SBr}_2$ or $\mathrm{SI}_2$. would there be cause to anticipate product disproportionation to $\mathrm{S}_{\mathrm{2}}$ and $\mathrm{SX}_6$ ?

Aadit Sharma
Aadit Sharma
Numerade Educator
04:27

Problem 80

Can the stabilities of $\mathrm{SF}_6$ and $\mathrm{S}_2 \mathrm{~F}_{10}$ toward hydrolysis be thermodynamic in origin? In answering. propose as hydrolysis products reasonable oxyacids, exclusive of redox reactions with $\mathrm{H}_2 \mathrm{O}$.

Ronald Prasad
Ronald Prasad
Numerade Educator
03:36

Problem 81

Should $\mathrm{SO}_2^{-}$be a o or $\pi$ radical (what does the HOMO, Chapter 5, look like)? Does your prediction help to explain the structural features of dithionite [long $\mathrm{S}-\mathrm{S}$ bond of $2.4 \mathrm{~A}$, nearly parallel $\mathrm{SO}_2$ planes, and eclipsed $\left(C_{2 v}\right)$ geometryl? Is there an analogy here with $(\mathrm{NO})_2$ and $\mathrm{N}_2 \mathrm{O}_4$ ?

Aadit Sharma
Aadit Sharma
Numerade Educator
04:44

Problem 82

From donor/acceptor concepts, predict possible structures for $\mathrm{S}_2 \mathrm{O}_5^{2-}$. Identify the donor and acceptor atoms in each case.

Rajesh Singh
Rajesh Singh
Numerade Educator
03:46

Problem 83

By analogy with the hydrolysis of $\mathrm{SO}_3$. propose a synthesis method for $\mathrm{HS}_4 \mathrm{SO}_3 \mathrm{H}$.

Colton Brushwood
Colton Brushwood
Numerade Educator
01:53

Problem 84

Propose a mechanism for the incorporation
$$
\mathrm{S}_2 \mathrm{O}_4^{2-}+{ }^* \mathrm{SO}_2 \leadsto \mathrm{O}_2 \mathrm{~S}^* \mathrm{SO}_2^2+\mathrm{SO}_2
$$
of labeled sulfur dioxide into dithionite.

Lottie Adams
Lottie Adams
Numerade Educator
03:36

Problem 85

Compare the series of $\mathrm{S}_z \mathrm{O}_y^{n-}$ and $\mathrm{Cl}_z \mathrm{O}_y$ compounds for correspondence. As the structures of $\mathrm{Cl}_2 \mathrm{O}_3$ and $\mathrm{Cl}_2 \mathrm{O}_6$ are not known, do you feel confident in assuming, by analogy, they have the structures of $\mathrm{S}_2 \mathrm{O}_3^{2-}$ and $\mathrm{S}_2 \mathrm{O}_6^{2-}$ ? What other reasonable structures for $\mathrm{Cl}_2 \mathrm{O}_3$ and $\mathrm{Cl}_2 \mathrm{O}_6$ can you suggest?

VS
Vivek Singh
Numerade Educator
01:28

Problem 86

Why do you suppose that oxygen, but not fluorine, is found combined with chlorine in the +7 oxidation state? Is the reason for the chemical inertness of $\mathrm{SF}_6$ related to the basis for your answer?

Adriano Chikande
Adriano Chikande
Numerade Educator
16:39

Problem 87

Contrast the structures of $\mathrm{Cl}_2 \mathrm{O}_7, \mathrm{~B}_2 \mathrm{H}_7^{-}, \mathrm{Al}_2 \mathrm{Cl}_7, \mathrm{~S}_2 \mathrm{O}_7^{-}$, and $\left(\mathrm{Cl}_3 \mathrm{Si}_2\right)_2 \mathrm{O}$.

Matthew Bittner
Matthew Bittner
Numerade Educator
07:42

Problem 88

Estimate the energy for the reactions
$$
\begin{aligned}
\mathrm{FXeN}\left(\mathrm{SO}_3 \mathrm{~F}\right)_2 & \rightarrow \mathrm{Xe}+\mathrm{FN}\left(\mathrm{SO}_3 \mathrm{~F}\right)_2 \\
& \rightarrow \mathrm{Xe}+\frac{1}{2} \mathrm{~F}_2+\frac{1}{2}\left(\mathrm{FSO}_3\right)_2 \mathrm{~N}_2
\end{aligned}
$$
in order to estimate the thermodynamically more favored decomposition products (the $\mathrm{XeN}$ bond energy is unknown). Assuming the favored reaction to be exothermic, place an upper limit on $E_{\text {xeN }}$.

Iryna Ivaniuk
Iryna Ivaniuk
Numerade Educator
00:33

Problem 89

Predict structures and point group symbols for $\mathrm{XeOF}_2, \mathrm{XeOF}_4, \mathrm{XeO}_2 \mathrm{~F}_2$, and $\mathrm{XeO}_3 \mathrm{~F}_2$.

Ayushi Sambyal
Ayushi Sambyal
Numerade Educator
01:22

Problem 90

Would the synthesis of $\mathrm{XeOF}_4$ by $\mathrm{XeF}_6$ hydrolysis in the gas phase probably be exothermic?

Lottie Adams
Lottie Adams
Numerade Educator
24:13

Problem 91

a) Using Pauling's thermochemical method (see problem 79, p. 348) for estimating atom electronegativities, insert the $\mathrm{XeF}$ and $\mathrm{XeO}$ thermochemical bond energies to estimate $X_{x_e} . \mathrm{Xe}$ is like what halogens in its $\chi$ values?
b) After considering the Lewis dot structure for $\mathrm{XeO}_4$ and/or after reading the discussion supporting Figure 4-16, criticize the view that the Xe-O bond is a "normal" a bond.

Susan Hallstrom
Susan Hallstrom
Numerade Educator
03:29

Problem 92

To which neutral and ionic halogen compounds are the known $\mathrm{XeF}_{\mathrm{n}}$ and $\mathrm{XeO}_n$ compounds similar?

Aadit Sharma
Aadit Sharma
Numerade Educator