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Chemistry and Chemical Reactivity

John C. Kotz, Paul M. Treichel, Gabriela C. Weaver

Chapter 9

Bonding and Molecular Structure: Fundamental Concepts - all with Video Answers

Educators

Chapter Questions

01:50

Problem 1

Give the periodic group number and number of valence electrons for each of the following atoms.
(a) $\mathrm{O}$
(d) $\mathrm{Mg}$
(b) $B$
(e) $\mathrm{F}$
(c) $\mathrm{Na}$
(f) $\mathrm{S}$

Maiah Brush
Maiah Brush
Numerade Educator
01:40

Problem 2

Give the periodic group number and number of valence electrons for each of the following atoms.
(a) $\mathrm{C}$
(d) Si
(b) $\mathrm{Cl}$
(e) Se
(c) $\mathrm{Ne}$
(f) $\mathrm{Al}$

Bryan Li
Bryan Li
Numerade Educator
01:20

Problem 3

For elements in Groups $3 \mathrm{A}-7 \mathrm{A}$ of the periodic table, give the number of bonds an element is expected to form if it obeys the octet rule.

Maiah Brush
Maiah Brush
Numerade Educator
01:58

Problem 4

Which of the following elements are capable of forming compounds in which the indicated atom has more than four valence electron pairs?
(a) C
(b) P
(c) O
(d) F
(c) Cl
(f) B
(g) Se
(h) $\mathrm{Sn}$

Bryan Li
Bryan Li
Numerade Educator
04:41

Problem 5

Which compound has the most negative energy of ion pair formation? Which has the least negative value?
(a) $\mathrm{NaCl}$
(b) MgS
(c) $\mathrm{KI}$

Kathleen Pankow
Kathleen Pankow
Numerade Educator
06:45

Problem 6

Which of the following ionic compounds are not likely to exist: $\mathrm{MgCl}, \mathrm{ScCl}_{3}, \mathrm{BaF}_{3}, \mathrm{CsKr}, \mathrm{Na}_{2} \mathrm{O} ?$ Explain your choices.

Bryan Li
Bryan Li
Numerade Educator
02:11

Problem 7

List the following compounds in order of increasing lattice energy (from least negative to most negative): LiI, LiF, $\mathrm{CaO}, \mathrm{RbI}$.

G Macdonald
G Macdonald
Numerade Educator
07:33

Problem 8

Calculate the molar enthalpy of formation, $\Delta H_{f}^{\circ},$ of solid lithium fluoride using the approach outlined on pages $378-381 . \Delta H_{f}^{\circ}[\mathrm{Li}(\mathrm{g})]=159.37 \mathrm{kJ} / \mathrm{mol},$ and other required data can be found in Appendices $F$ and $L$. (See also Exercise $9.2 .)$

Bryan Li
Bryan Li
Numerade Educator
01:34

Problem 9

To melt an ionic solid, energy must be supplied to disrupt the forces between ions so the regular array of ions collapses. If the distance between the anion and the cation in a crystalline solid decreases (but ion charges remain the same), should the melting point decrease or increase? Explain.

Kathleen Pankow
Kathleen Pankow
Numerade Educator
06:22

Problem 10

Which compound in each of the following pairs should require the higher temperature to melt? (See Study Question $9 .)$
(a) NaCl or RbCl
(b) $\mathrm{BaO}$ or $\mathrm{MgO}$
(c) $\mathrm{NaCl}$ or $\mathrm{MgS}$

Bryan Li
Bryan Li
Numerade Educator
14:12

Problem 11

Draw a Lewis structure for each of the following molecules or ions.
(a) $\mathrm{NF}_{3}$
(b) $\mathrm{ClO}_{3}^{-}$
(c) HOBr
(d) $\mathrm{SO}_{3}^{2-}$

Maiah Brush
Maiah Brush
Numerade Educator
15:02

Problem 12

Draw a Lewis structure for each of the following molecules or ions:
(a) $\mathrm{CS}_{2}$
(b) $\mathrm{BF}_{4}^{-}$
(c) $\mathrm{NO}_{2}^{-}$
(d) $\mathrm{SOCl}_{2}$

Bryan Li
Bryan Li
Numerade Educator
11:48

Problem 13

Draw a Lewis structure for each of the following molecules:
(a) Chlorodifluoromethane, $\mathrm{CHClF}_{2}$ (C is the central atom)
(b) Acetic acid, $\mathrm{CH}_{3} \mathrm{CO}_{2} \mathrm{H}$. Its basic structure is pictured.
(EQUATION CAN'T COPY)
(c) Acetonitrile, $\mathrm{CH}_{3} \mathrm{CN}$ (the framework is $\mathrm{H}_{3} \mathrm{C}-\mathrm{C}-\mathrm{N}$ )
(d) Allene, $\mathrm{H}_{2} \mathrm{CCCH}_{2}$

Maiah Brush
Maiah Brush
Numerade Educator
10:48

Problem 14

Draw a Lewis structure for each of the following molecules.
(a) Methanol, $\mathrm{CH}_{3} \mathrm{OH}$ (C is the central atom)
(b) Vinyl chloride, $\mathrm{H}_{2} \mathrm{C}=\mathrm{CHCl}$, the molecule from which
PVC plastics are made.
(c) Acrylonitrile, $\mathrm{H}_{2} \mathrm{C}=\mathrm{CHCN}$, the molecule from which materials such as Orlon are made.
(EQUATION CAN'T COPY)

Bryan Li
Bryan Li
Numerade Educator
10:17

Problem 15

Show all possible resonance structures for each of the following molecules or ions.
(a) $\mathrm{SO}_{2}$
(b) $\mathrm{NO}_{2}^{-}$
(c) $\mathrm{SCN}^{-}$

Maiah Brush
Maiah Brush
Numerade Educator
10:58

Problem 16

Show all possible resonance structures for each of the following molecules or ions:
(a) Nitrate ion, $\mathrm{NO}_{3}^{-}$
(b) Nitric acid, HNO $_{3}$
(c) Nitrous oxide (laughing gas), $\mathrm{N}_{2} \mathrm{O}$

Bryan Li
Bryan Li
Numerade Educator
07:35

Problem 17

Draw a Lewis structure for each of the following molecules or ions.
(a) $\mathrm{BrF}_{3}$
(b) $\mathrm{I}_{3}^{-}$
(c) $\mathrm{XeO}_{2} \mathrm{F}_{2}$
(d) $\mathrm{XeF}_{3}^{+}$

Kathleen Pankow
Kathleen Pankow
Numerade Educator
07:45

Problem 18

Draw a Lewis structure for each of the following molecules or ions:
(a) $\mathrm{BrF}_{5}$
(b) IF $_{3}$
(c) $\mathrm{IBr}_{2}^{-}$
(d) $\mathrm{BrF}_{2}^{+}$

Bryan Li
Bryan Li
Numerade Educator
09:16

Problem 19

Draw a Lewis structure for each of the following molecules or ions. Describe the electron-pair geometry and the molecular geometry around the central atom.
(a) $\mathrm{NH}_{2} \mathrm{Cl}$
(b) $\mathrm{Cl}_{2} \mathrm{O}$ (O is the central atom)
(c) $\mathrm{SCN}^{-}$
(d) HOF

Kathleen Pankow
Kathleen Pankow
Numerade Educator
15:01

Problem 20

Draw a Lewis structure for each of the following molecules or ions. Describe the electron-pair geometry and the molecular geometry around the central atom.
(a) $\mathrm{ClF}_{2}^{+}$
(b) $\mathrm{SnCl}_{3}^{-}$
(c) $\mathrm{PO}_{4}^{3-}$
(d) $\mathrm{CS}_{2}$

Bryan Li
Bryan Li
Numerade Educator
08:27

Problem 21

The following molecules or ions all have two oxygen atoms attached to a central atom. Draw a Lewis structure for each one and then describe the electron-pair geometry and the molecular geometry around the central atom. Comment on similarities and differences in the series.
(a) $\mathrm{CO}_{2}$
(b) $\mathrm{NO}_{2}^{-}$
(c) $\mathrm{O}_{3}$
(d) $\mathrm{ClO}_{2}^{-}$

Kathleen Pankow
Kathleen Pankow
Numerade Educator
10:12

Problem 22

The following molecules or ions all have three oxygen atoms attached to a central atom. Draw a Lewis structure for each one and then describe the electron-pair geometry and the molecular geometry around the central atom. Comment on similarities and differences in the series.
(a) $\mathrm{CO}_{3}^{2-}$
(b) $\mathrm{NO}_{3}^{-}$
(c) $\mathrm{SO}_{3}^{2-}$
(d) $\mathrm{ClO}_{3}^{-}$

Bryan Li
Bryan Li
Numerade Educator
09:28

Problem 23

Draw a Lewis structure for each of the following molecules or ions. Describe the electron-pair geometry and the molecular geometry around the central atom.
(a) $\mathrm{ClF}_{2}^{-}$
(b) $\mathrm{ClF}_{3}$
(c) $\mathrm{CIF}_{4}^{-}$
(d) CIF $_{5}$

Kathleen Pankow
Kathleen Pankow
Numerade Educator
10:33

Problem 24

Draw a Lewis structure of each of the following molecules or ions. Describe the electron-pair geometry and the molecular geometry around the central atom.
(a) $\mathrm{SiF}_{6}^{2-}$
(b) $\mathrm{PF}_{5}$
(c) $\mathrm{SF}_{4}$
(d) $\mathrm{XeF}_{4}$

Bryan Li
Bryan Li
Numerade Educator
08:36

Problem 25

Give approximate values for the indicated bond angles.
(a) $\mathrm{O}-\mathrm{S}-\mathrm{O}$ in $\mathrm{SO}_{2}$
(b) $\mathrm{F}-\mathrm{B}-\mathrm{F}$ angle in $\mathrm{BF}_{3}$
(c) $\mathrm{Cl}-\mathrm{C}-\mathrm{Cl}$ angle in $\mathrm{Cl}_{2} \mathrm{CO}$
(c) $\mathrm{H}-\mathrm{C}-\mathrm{H}$ (angle 1 ) and $\mathrm{C}-\mathrm{C} \equiv \mathrm{N}$ (angle 2 ) in acetonitrile.
(EQUATION CAN'T COPY)

Kathleen Pankow
Kathleen Pankow
Numerade Educator
05:28

Problem 26

Give approximate values for the indicated bond angles.
(a) $\mathrm{Cl}-\mathrm{S}-\mathrm{Cl}$ in $\mathrm{SCl}_{2}$
(b) $\mathrm{N}-\mathrm{N}-\mathrm{O}$ in $\mathrm{N}_{2} \mathrm{O}$
(c) Bond angles in vinyl alcohol (a component of polymers and another molecule found in space).
(EQUATION CAN'T COPY)

Bryan Li
Bryan Li
Numerade Educator
06:02

Problem 27

Phenylalanine is one of the natural amino acids and is a "breakdown" product of aspartame. Estimate the values of the indicated angles in the amino acid. Explain why the $\mathrm{CH}_{2}\mathrm{CH}\left(\mathrm{NH}_{2}\right)-\mathrm{CO}_{2} \mathrm{H}$ chain is not linear.
(EQUATION CAN'T COPY)

Kathleen Pankow
Kathleen Pankow
Numerade Educator
03:10

Problem 28

Acetylacetone has the structure shown here. Estimate the values of the indicated angles.
(EQUATION CAN'T COPY)

Bryan Li
Bryan Li
Numerade Educator
12:21

Problem 29

Determine the formal charge on each atom in the following molecules or ions:
(a) $\mathrm{N}_{2} \mathrm{H}_{4}$
(c) $\mathrm{BH}_{4}^{-}$
(b) $\mathrm{PO}_{4}^{3-}$
(d) $\mathrm{NH}_{2} \mathrm{OH}$

Kathleen Pankow
Kathleen Pankow
Numerade Educator
12:48

Problem 30

Determine the formal charge on each atom in the following molecules or ions.
(a) SCO
(b) $\mathrm{HCO}_{2}^{-}$ (formate ion)
(c) $\mathbf{O}_{3}$
(d) $\mathrm{HCO}_{2} \mathrm{H}$ (formic acid)

Bryan Li
Bryan Li
Numerade Educator
13:19

Problem 31

Determine the formal charge on each atom in the following molecules and ions.
(a) $\mathrm{NO}_{2}^{+}$
(c) $\mathrm{NF}_{3}$
(b) $\mathrm{NO}_{2}^{-}$
(d) HNO $_{3}$

Kathleen Pankow
Kathleen Pankow
Numerade Educator
13:34

Problem 32

Determine the formal charge on each atom in the following molecules and ions.
(a) $\mathrm{SO}_{2}$
(c) $\mathrm{SO}_{2} \mathrm{Cl}_{2}$
(b) $\mathrm{SOCl}_{2}$
(d) $\mathrm{FSO}_{3}^{-}$

Bryan Li
Bryan Li
Numerade Educator
03:41

Problem 33

For each pair of bonds, indicate the more polar bond and use an arrow to show the direction of polarity in each bond.
(a) $\mathrm{C}-\mathrm{O}$ and $\mathrm{C}-\mathrm{N}$
(c) $\mathrm{B}-\mathrm{O}$ and $\mathrm{B}-\mathrm{S}$
(b) $\mathrm{P}-\mathrm{Br}$ and $\mathrm{P}-\mathrm{Cl}$
(d) $\mathrm{B}-\mathrm{F}$ and $\mathrm{B}-\mathrm{I}$

Maiah Brush
Maiah Brush
Numerade Educator
04:56

Problem 34

For each of the bonds listed below, tell which atom is the more negatively charged.
(a) $\mathrm{C}-\mathrm{N}$
(c) $\mathrm{C}-\mathrm{Br}$
(b) $\mathrm{C}-\mathrm{H}$
(d) $\mathrm{S}-\mathrm{O}$

Bryan Li
Bryan Li
Numerade Educator
03:13

Problem 35

Acrolein, $C_{3} H_{4} O,$ is the starting material for certain plastics. (EQUATION CAN'T COPY) (a) Which bonds in the molecule are polar and which are nonpolar?
(b) Which is the most polar bond in the molecule? Which is the more negative atom of this bond?

Kathleen Pankow
Kathleen Pankow
Numerade Educator
02:37

Problem 36

Urea, $\left(\mathrm{NH}_{2}\right)_{2} \mathrm{CO},$ is used in plastics and fertilizers. It is also the primary nitrogen-containing substance excreted by humans.
(a) Which bonds in the molecule are polar and which are nonpolar?
(b) Which is the most polar bond in the molecule? Which atom is the negative end of the bond dipole?
(EQUATION CAN'T COPY)

Bryan Li
Bryan Li
Numerade Educator
12:45

Problem 37

Considering both formal charges and bond polarities, predict on which atom or atoms the negative charge resides in the following anions:
(a) $\mathrm{OH}^{-}$
(b) $\mathrm{BH}_{4}^{-}$
(c) $\mathrm{CH}_{3} \mathrm{CO}_{2}^{-}$

Kathleen Pankow
Kathleen Pankow
Numerade Educator
11:19

Problem 38

Considering both formal charge and bond polarities, predict on which atom or atoms the positive charge resides in the following cations.
(a) $\mathrm{H}_{3} \mathrm{O}^{+}$
(c) $\mathrm{NO}_{2}^{+}$
(b) $\mathrm{NH}_{4}^{+}$
(d) $\mathrm{NF}_{4}^{+}$

Bryan Li
Bryan Li
Numerade Educator
09:38

Problem 39

Three resonance structures are possible for dinitrogen oxide, $\mathrm{N}_{2} \mathrm{O}$
(a) Draw the three resonance structures.
(b) Calculate the formal charge on each atom in each resonance structure.
(c) Based on formal charges and electro negativity, predict which resonance structure is the most reasonable.

Kathleen Pankow
Kathleen Pankow
Numerade Educator
09:35

Problem 40

Compare the electron dot structures of the carbonate $\left(\mathrm{CO}_{3}^{2-}\right)$ and borate $\left(\mathrm{BO}_{3}^{3-}\right)$ ions.
(a) Are these ions isoelectronic?
(b) How many resonance structures does each ion have?
(c) What are the formal charges of each atom in these ions?
(d) If an $\mathrm{H}^{+}$ ion attaches to $\mathrm{CO}_{3}^{2-}$ to form the bicarbonate ion, $\mathrm{HCO}_{3}^{-},$ does it attach to an $\mathrm{O}$ atom or to the Catom?

Bryan Li
Bryan Li
Numerade Educator
05:43

Problem 41

Two resonance structures are possible for $\mathrm{NO}_{2}^{-} .$ Draw these structures and then find the formal charge on each atom in each resonance structure. If an $\mathrm{H}^{+}$ ion is attached to $\mathrm{NO}_{2}^{-}$ (to form the acid $\mathrm{HNO}_{2}$ ), does it attach to $\mathrm{O}$ or N?

Kathleen Pankow
Kathleen Pankow
Numerade Educator
08:22

Problem 42

Draw the resonance structures for the formate ion, $\mathrm{HCO}_{2}^{-}$ and find the formal charge on each atom. If an $\mathrm{H}^{+}$ ion is attached to $\mathrm{HCO}_{2}^{-}$ (to form formic acid), does it attach to
Cor O?

Bryan Li
Bryan Li
Numerade Educator
11:43

Problem 43

Consider the following molecules:
(a) $\mathrm{H}_{2} \mathrm{O}$
(c) $\mathrm{CO}_{2}$
(e) $\mathrm{CCl}_{4}$
(b) $\mathrm{NH}_{3}$
(d) CIF
(i) In which compound are the bonds most polar?
(ii) Which compounds in the list are not polar?
(iii) Which atom in CIF is more negatively charged?

Kathleen Pankow
Kathleen Pankow
Numerade Educator
08:48

Problem 44

Consider the following molecules:
(a) $\mathrm{CH}_{4}$
(c) $\mathrm{BF}_{3}$
(b) $\mathrm{NH}_{2} \mathrm{Cl}$
(d) $\mathrm{CS}_{2}$
(i) Which compound has the most polar bonds?
(ii) Which compounds in the list are not polar?

Bryan Li
Bryan Li
Numerade Educator
10:44

Problem 45

Which of the following molecules is (are) polar? For each polar molecule, indicate the direction of polarity-that is, which is the negative end and which is the positive end of the molecule.
(a) $\mathrm{BeCl}_{2}$
(c) $\mathrm{CH}_{3} \mathrm{Cl}$
(b) $\mathrm{HBF}_{2}$
(d) $\mathrm{SO}_{3}$

Kathleen Pankow
Kathleen Pankow
Numerade Educator
06:38

Problem 46

Which of the following molecules is (are) not polar? Which molecule has the most polar bonds?
(a) CO
(d) $\mathrm{PCl}_{3}$
(b) $\mathrm{BCl}_{3}$
(e) $\mathrm{GeH}_{4}$
(c) $\mathrm{CF}_{4}$

Bryan Li
Bryan Li
Numerade Educator
09:45

Problem 47

Give the bond order for each bond in the following molecules or ions.
(a) $\mathrm{CH}_{2} \mathrm{O}$
(c) $\mathrm{NO}_{2}^{+}$
(b) $\mathrm{SO}_{3}^{2-}$
(d) NOCl

Kathleen Pankow
Kathleen Pankow
Numerade Educator
04:51

Problem 48

Give the bond order for each bond in the following molecules or ions.
(a) $\mathrm{CN}^{-}$
(b) $\mathrm{CH}_{3} \mathrm{CN}$
(c) $\mathrm{SO}_{3}$
(d) $\mathrm{CH}_{3} \mathrm{CH}=\mathrm{CH}_{2}$

Bryan Li
Bryan Li
Numerade Educator
03:41

Problem 49

In each pair of bonds, predict which is shorter.
(a) $\mathrm{B}-\mathrm{Cl}$ or $\mathrm{Ga}-\mathrm{Cl}$
(b) $\mathrm{Sn}-$ O or $\mathrm{C}-\mathrm{O}$
(c) $\mathrm{P}-\mathrm{S}$ or $\mathrm{P}-\mathrm{O}$
(d) $\mathrm{C}=\mathrm{O}$ or $\mathrm{C}=\mathrm{N}$

Kathleen Pankow
Kathleen Pankow
Numerade Educator
05:53

Problem 50

In each pair of bonds, predict which is shorter.
(a) $\mathrm{Si}-\mathrm{N}$ or $\mathrm{Si}-\mathrm{O}$
(b) $\mathrm{Si}-\mathrm{O}$ or $\mathrm{C}-\mathrm{O}$
(c) $\mathrm{C}-\mathrm{F}$ or $\mathrm{C}-\mathrm{Br}$
(d) The $\mathrm{C}-\mathrm{N}$ bond or the $\mathrm{C} \equiv \mathrm{N}$ bond in $\mathrm{H}_{2} \mathrm{NCH}_{2} \mathrm{C} \equiv \mathrm{N}$

Bryan Li
Bryan Li
Numerade Educator
08:28

Problem 51

Consider the nitrogen-oxygen bond lengths in $\mathrm{NO}_{2}^{+}$ $\mathrm{NO}_{2}^{-},$ and $\mathrm{NO}_{3}^{-} .$ In which ion is the bond predicted to be longest? In which is it predicted to be the shortest? Explain briefly.

Kathleen Pankow
Kathleen Pankow
Numerade Educator
06:49

Problem 52

Compare the carbon-oxygen bond lengths in the formate ion $\left(\mathrm{HCO}_{2}^{-}\right),$ in methanol $\left(\mathrm{CH}_{3} \mathrm{OH}\right),$ and in the carbonate ion $\left(\mathrm{CO}_{3}^{2-}\right) .$ In which species is the carbon-oxygen bond predicted to be longest? In which is it predicted to be shortest? Explain briefly.

Bryan Li
Bryan Li
Numerade Educator
05:16

Problem 53

Consider the carbon-oxygen bond in formaldehyde $\left(\mathrm{CH}_{2} \mathrm{O}\right)$ and carbon monoxide (CO). In which molecule is the CO bond shorter? In which molecule is the CO bond stronger?

Kathleen Pankow
Kathleen Pankow
Numerade Educator
03:13

Problem 54

Compare the nitrogen-nitrogen bond in hydrazine, $\mathrm{H}_{2} \mathrm{NNH}_{2},$ with that in "laughing gas," $\mathrm{N}_{2} \mathrm{O}$. In which molecule is the nitrogen-nitrogen bond shorter? In which is the bond stronger?

Bryan Li
Bryan Li
Numerade Educator
03:37

Problem 55

Hydrogenation reactions, which involve the addition of $\mathrm{H}_{2}$ to a molecule, are widely used in industry to transform one compound into another. For example, 1-butene $\left(\mathrm{C}_{4} \mathrm{H}_{8}\right)$ is converted to butane $\left(\mathrm{C}_{4} \mathrm{H}_{10}\right)$ by addition of $\mathrm{H}_{2}$.
(EQUATION CAN'T COPY)
Use the bond energies of Table 9.10 to estimate the enthalpy change for this hydrogenation reaction.

Kathleen Pankow
Kathleen Pankow
Numerade Educator
04:35

Problem 56

Phosgene, $\mathrm{Cl}_{2} \mathrm{CO},$ is a highly toxic gas that was used as weapon in World War I. Using the bond energies of Table 9.10, estimate the enthalpy change for the reaction of carbon monoxide and chlorine to produce phosgene. (Hint: First draw the electron dot structures of the reactants and products so you know the types of bonds involved.)$$\mathrm{CO}(\mathrm{g})+\mathrm{Cl}_{2}(\mathrm{g}) \longrightarrow \mathrm{Cl}_{2} \mathrm{CO}(\mathrm{g})$$.

Bryan Li
Bryan Li
Numerade Educator
05:59

Problem 57

The compound oxygen difluoride is quite reactive, giving oxygen and HF when treated with water:$$\begin{aligned}\mathrm{OF}_{2}(\mathrm{g})+\mathrm{H}_{2} \mathrm{O}(\mathrm{g}) & \longrightarrow \mathrm{O}_{2}(\mathrm{g})+2 \mathrm{HF}(\mathrm{g}) \\\Delta H_{\mathrm{rxn}}^{\circ} &=-318 \mathrm{kJ}\end{aligned}$$.Using bond energies, calculate the bond dissociation energy of the $\mathbf{O}-$ F bond in $\mathrm{OF}_{2}$.

Kathleen Pankow
Kathleen Pankow
Numerade Educator
06:24

Problem 58

Oxygen atoms can combine with ozone to form oxygen: $$\mathrm{O}_{3}(\mathrm{g})+\mathrm{O}(\mathrm{g}) \longrightarrow 2 \mathrm{O}_{2}(\mathrm{g}) \quad \Delta H_{\mathrm{rxn}}^{\circ}=-394 \mathrm{kJ}$$,Using $\Delta H_{\mathrm{ren}}^{\circ}$ and the bond energy data in Table 9.10 estimate the bond energy for the oxygen-oxygen bond in ozone, $\mathbf{O}_{3} .$ How does your estimate compare with the energies of an $\mathrm{O}-\mathrm{O}$ single bond and an $\mathrm{O}=\mathrm{O}$ double bond? Does the oxygen-oxygen bond energy in ozone correlate with its bond order?

Bryan Li
Bryan Li
Numerade Educator
02:03

Problem 59

Specify the number of valence electrons for $\mathrm{Li}, \mathrm{Ti}, \mathrm{Zn}, \mathrm{Si}$ and Cl.

Rolly Sharda
Rolly Sharda
Numerade Educator
01:48

Problem 60

Describe the formation of KF from K and F atoms using Lewis symbols. Is bonding in KF ionic or covalent?

Bryan Li
Bryan Li
Numerade Educator
02:02

Problem 61

Predict whether the following compounds are ionic or covalent: $\mathrm{KI}, \mathrm{MgS}, \mathrm{CS}_{2}, \mathrm{P}_{4} \mathrm{O}_{10}$.

Kathleen Pankow
Kathleen Pankow
Numerade Educator
03:15

Problem 62

Define lattice energy. Which should have the more negative lattice energy, LiF or CsF? Explain.

Bryan Li
Bryan Li
Numerade Educator
01:43

Problem 63

Which compound is not likely to exist: $\operatorname{CaCl}_{2}$ or $\mathrm{CaCl}_{4} ?$ Explain.

Kathleen Pankow
Kathleen Pankow
Numerade Educator
01:50

Problem 64

In boron compounds the B atom often is not surrounded by four valence electron pairs. Illustrate this with $\mathrm{BCl}_{3}$ Show how the molecule can achieve an octet configuration by forming a coordinate covalent bond with ammonia $\left(\mathrm{NH}_{3}\right)$.

Bryan Li
Bryan Li
Numerade Educator
05:51

Problem 65

Which of the following compounds or ions do not have an octet of electrons surrounding the central atom: $\mathbf{B F}_{4}^{-}$ $\mathrm{SiF}_{4}, \mathrm{SeF}_{4}, \mathrm{BrF}_{4}^{-}, \mathrm{XeF}_{4} ?^{-}$

Kathleen Pankow
Kathleen Pankow
Numerade Educator
08:44

Problem 66

In which of the following does the central atom obey the octet rule: $\mathrm{NO}_{2}, \mathrm{SF}_{4}, \mathrm{NH}_{3}, \mathrm{SO}_{3}, \mathrm{O}_{2}^{-}$ ? Are any of these species odd-electron molecules or ions?

Bryan Li
Bryan Li
Numerade Educator
03:17

Problem 67

Give the bond order of each bond in acetylene, $\mathrm{H}-\mathrm{C} \equiv \mathrm{C}-\mathrm{H},$ and phosgene, $\mathrm{Cl}_{2} \mathrm{CO}$.

Kathleen Pankow
Kathleen Pankow
Numerade Educator
03:51

Problem 68

Draw resonance structures for the formate ion, $\mathrm{HCO}_{2}^{-}$ and then determine the $\mathrm{C}-$ O bond order in the ion.

Bryan Li
Bryan Li
Numerade Educator
03:06

Problem 69

Determine the $\mathrm{N}-$ O bond order in the nitrate ion, $\mathrm{NO}_{3}^{-}$.

Kathleen Pankow
Kathleen Pankow
Numerade Educator
02:39

Problem 70

Consider a series of molecules in which carbon is bonded by single bonds to atoms of second-period elements:
$\mathrm{C}-\mathrm{O}, \mathrm{C}-\mathrm{F}, \mathrm{C}-\mathrm{N}, \mathrm{C}-\mathrm{C},$ and $\mathrm{C}-\mathrm{B} .$ Place these bonds in order of increasing bond length.

Bryan Li
Bryan Li
Numerade Educator
04:15

Problem 71

To estimate the enthalpy change for the reaction,$$\mathrm{O}_{2}(\mathrm{g})+2 \mathrm{H}_{2}(\mathrm{g}) \longrightarrow 2 \mathrm{H}_{2} \mathrm{O}(\mathrm{g})$$.What bond energies do you need? Outline the calculation, being careful to show correct algebraic signs.

Kathleen Pankow
Kathleen Pankow
Numerade Educator
04:55

Problem 72

What is the principle of electroN neutrality? Use this rule to exclude a possible resonance structure of $\mathrm{CO}_{2}$

Bryan Li
Bryan Li
Numerade Educator
06:55

Problem 73

Draw Lewis structures (and resonance structures where appropriate) for the following molecules and ions. What similarities and differences are there in this series?
(a) $\mathrm{CO}_{2}$
(b) $\mathrm{N}_{3}^{-}$
(c) OCN

Kathleen Pankow
Kathleen Pankow
Numerade Educator
02:52

Problem 74

Does SO $_{2}$ have a dipole moment? If so, what is the direction of the net dipole in $\mathrm{SO}_{2} ?$

Bryan Li
Bryan Li
Numerade Educator
05:59

Problem 75

What are the orders of the $\mathrm{N}-$ O bonds in $\mathrm{NO}_{2}^{-}$ and $\mathrm{NO}_{2}^{+} ?$ The nitrogen-oxygen bond length in one of these ions is $110 \mathrm{pm}$ and $124 \mathrm{pm}$ in the other. Which bond length corresponds to which ion? Explain briefly.

Kathleen Pankow
Kathleen Pankow
Numerade Educator
04:48

Problem 76

Which has the greater $\mathbf{O}-\mathbf{N}-\mathbf{O}$ bond angle, $\mathbf{N O}_{2}^{-}$ or $\mathrm{NO}_{2}^{+} ?$ Explain briefly.

Bryan Li
Bryan Li
Numerade Educator
03:54

Problem 77

Compare the $\mathrm{F}-\mathrm{Cl}-\mathrm{F}$ angles in $\mathrm{ClF}_{2}^{+}$ and $\mathrm{ClF}_{2}^{-} .$ Using Lewis structures, determine the approximate bond angle in each ion. Decide which ion has the greater bond angle and explain your reasoning.

Kathleen Pankow
Kathleen Pankow
Numerade Educator
04:08

Problem 78

Draw an electron dot structure for the cyanide ion, $\mathrm{CN}^{-}$. In aqueous solution this ion interacts with $\mathrm{H}^{+}$ to form the acid. Should the acid formula be written as HCN or CNH?

Bryan Li
Bryan Li
Numerade Educator
01:55

Problem 79

Draw the electron dot structure for the sulfite ion, $\mathrm{SO}_{3}^{2-}$ In aqueous solution the ion interacts with $\mathrm{H}^{+}$. Does $\mathrm{H}^{+}$ attach itself to the S atom or the O atom of $\mathrm{SO}_{3}^{2-} ?$

Kathleen Pankow
Kathleen Pankow
Numerade Educator
04:57

Problem 80

Dinitrogen monoxide, $\mathrm{N}_{2} \mathrm{O},$ can decompose to nitrogen and oxygen gas: $$2 \mathrm{N}_{2} \mathrm{O}(\mathrm{g}) \longrightarrow 2 \mathrm{N}_{2}(\mathrm{g})+\mathrm{O}_{2}(\mathrm{g})$$,Use bond energies to estimate the enthalpy change for this reaction.

Bryan Li
Bryan Li
Numerade Educator
01:38

Problem 81

The equation for the combustion of gaseous methanol is $$2 \mathrm{CH}_{3} \mathrm{QH}(\mathrm{g})+3 \mathrm{Q}_{3}(\mathrm{g}) \longrightarrow 2 \mathrm{CQ}_{2}(\mathrm{g})+4 \mathrm{H}_{2} \mathrm{Q}(\mathrm{g})$$.(a) Using the bond energies in Table 9.10 , estimate the enthalpy change for this reaction. What is the heat of combustion of one mole of gaseous methanol?
(b) Compare your answer in part (a) with a calculation of $\Delta H_{\mathrm{ran}}^{\circ}$ using thermochemical data and the methods of Chapter 6 (see Equation 6.6 ).

Lottie Adams
Lottie Adams
Numerade Educator
04:17

Problem 82

Acrylonitrile, $\mathrm{C}_{3} \mathrm{H}_{3} \mathrm{N},$ is the building block of the synthetic fiber Orlon.
(EQUATION CAN'T COPY)
(a) Give the approximate values of angles $1,2,$ and 3
(b) Which is the shorter carbon-carbon bond?
(c) Which is the stronger carbon-carbon bond?
(d) Which is the most polar bond?

Bryan Li
Bryan Li
Numerade Educator
06:10

Problem 83

The cyanate ion, NCO", has the least electronegative atom, $\mathbf{C},$ in the center. The very unstable fulminate ion, CNO $^{-}$, has the same formula, but the $\mathrm{N}$ atom is in the center.
(a) Draw the three possible resonance structures of $\mathrm{CNO}^{-}$
(b) On the basis of formal charges, decide on the resonance structure with the most reasonable distribution of charge.
(c) Mercury fulminate is so unstable it is used in blasting caps. Can you offer an explanation for this instability? (Hint: Are the formal charges in any resonance structure reasonable in view of the relative electron negativities of the atoms?)

Kathleen Pankow
Kathleen Pankow
Numerade Educator
04:46

Problem 84

Vanillin is the flavoring agent in vanilla extract and in vanilla ice cream. Its structure is shown here:
(EQUATION CAN'T COPY)
(a) Give values for the three bond angles indicated.
(b) Indicate the shortest carbon-oxygen bond in the molecule.
(c) Indicate the most polar bond in the molecule.

Bryan Li
Bryan Li
Numerade Educator
05:10

Problem 85

Given that the spatial requirement of a lone pair is much greater than that of a bond pair, explain why
(a) $\mathrm{XeF}_{2}$ has a linear molecular structure and not a bent one.
(b) CIF $_{3}$ has a T-shaped structure and not a trigonal-planar one.

Kathleen Pankow
Kathleen Pankow
Numerade Educator
03:52

Problem 86

The formula for nitryl chloride is $\mathrm{CINO}_{2} .$ Draw the Lewis structure for the molecule, including all resonance structures. Describe the electron-pair and molecular geometries, and give values for all bond angles.

Bryan Li
Bryan Li
Numerade Educator
04:25

Problem 87

Hydroxyproline is a less common amino acid.
(EQUATION CAN'T COPY)
(a) Give approximate values for the indicated bond angles.
(b) Which are the most polar bonds in the molecule?

Kathleen Pankow
Kathleen Pankow
Numerade Educator
02:38

Problem 88

Amides are an important class of organic molecules. They are usually drawn as sketched here, but another resonance structure is possible.
(EQUATION CAN'T COPY)
(a) Draw that structure, and then suggest why it is usually not pictured.
(b) Suggest a reason for the fact that the $\mathrm{H}-\mathrm{N}-\mathrm{H}$ angle is close to $120^{\circ}$

Bryan Li
Bryan Li
Numerade Educator
05:31

Problem 89

Use the bond energies in Table 9.10 to calculate the enthalpy change for the decomposition of urea (Study Question 36 ) to hydrazine, $\mathrm{H}_{2} \mathrm{N}-\mathrm{NH}_{2},$ and carbon monoxide. (Assume all compounds are in the gas phase.)

Kathleen Pankow
Kathleen Pankow
Numerade Educator
08:56

Problem 90

The molecule shown here, 2 -furylmethanethiol, is responsible for the aroma of coffee:
(EQUATION CAN'T COPY)
(a) What are the formal charges on the $\mathrm{S}$ and $\mathrm{O}$ atoms?
(b) Give approximate values of angles $1,2,$ and 3
(c) Which are the shorter carbon-carbon bonds in the molecule?
(d) Which bond in this molecule is the most polar?
(e) Is the molecule as a whole polar or nonpolar?
(f) The molecular model makes it clear that the four $\mathbf{C}$ atoms of the ring are all in a plane. Is the O atom in that same plane (making the five-member ring planar), or is the $\mathrm{O}$ atom bent above or below the plane?

Bryan Li
Bryan Li
Numerade Educator
07:42

Problem 91

A Dihydroxyacetone is a component of quick-tanning lotions. (It reacts with the amino acids in the upper layer of skin and colors them brown in a reaction similar to that occurring when food is browned as it cooks.)
(a) Supposing you can make this compound by treating acetone with oxygen, use bond energies to estimate the enthalpy change for the following reaction (which is assumed to occur in the gas phase). Is the reaction exothermic or endothermic?
(EQUATION CAN'T COPY)
(b) Is acetone polar?
(c) Positive $\mathrm{H}$ atoms can sometimes be removed (as $\mathrm{H}^{+}$ ) from molecules with strong bases (which is in part what happens in the tanning reaction). Which $\mathrm{H}$ atoms are the most positive in dihydroxyacetone?

Kathleen Pankow
Kathleen Pankow
Numerade Educator
06:35

Problem 92

Nitric acid, HNO $_{3},$ has three resonance structures. One of them, however, contributes much less to the resonance hybrid than the other two. Sketch the three resonance structures and assign a formal charge to each atom. Which one of your structures is the least important?

Bryan Li
Bryan Li
Numerade Educator
07:53

Problem 93

Acrolein is used to make plastics. Suppose this compound can be prepared by inserting a carbon monoxide molecule into the $\mathrm{C}-\mathrm{H}$ bond of ethylene.
(EQUATION CAN'T COPY)
(a) Which is the stronger carbon-carbon bond in acrolein?
(b) Which is the longer carbon-carbon bond in acrolein?
(c) Is ethylene or acrolein polar?
(d) Is the reaction of CO with $\mathrm{C}_{2} \mathrm{H}_{4}$ to give acrolein endothermic or exothermic?

Kathleen Pankow
Kathleen Pankow
Numerade Educator
05:39

Problem 94

(a) Glycolaldehyde was featured in the story "Molecules in Space" (page 372 ). Indicate the unique bond angles in this molecule.
(b) One molecule found in the 1995 Hale-Bopp comet is HC $_{3}$ N. Suggest a structure for this molecule. (Hint: it is based on a chain of atoms.)

Bryan Li
Bryan Li
Numerade Educator
03:14

Problem 95

1.2-Dichloroethylene can be synthesized by adding $\mathrm{Cl}_{2}$ to the carbon-carbon triple bond of acetylene.
(EQUATION CAN'T COPY)
Using bond energies, estimate the enthalpy change for this reaction in the gas phase.

Kathleen Pankow
Kathleen Pankow
Numerade Educator
03:45

Problem 96

The following molecules or ions have fluorine atoms attached to a central atom from Groups $3 \mathrm{A}$ through $7 \mathrm{A}$. Draw the Lewis structure for each one and then describe the electron-pair geometry and the molecular geometry. Comment on similarities and differences in the series.
(a) $\mathrm{BF}_{3}$
(b) $\mathrm{CF}_{4}$
(c) $\mathrm{PF}_{3}$
(d) $\mathrm{OF}_{2}$
(e) $\mathrm{HF}$

Bryan Li
Bryan Li
Numerade Educator
04:08

Problem 97

The molecule pictured below is epinephrine, a compound used as a bronchodilator and anti-glaucoma agent.
(EQUATIONS CAN'T COPY)
(a) Give a value for each of the indicated bond angles.
(b) What are the most polar bonds in the molecule?

Kathleen Pankow
Kathleen Pankow
Numerade Educator
02:32

Problem 98

Define "bond dissociation energy." Does the enthalpy change for a bond-breaking reaction [e.g., $\mathrm{C}-\mathrm{H}(\mathrm{g}) \longrightarrow \mathrm{C}(\mathrm{g})+\mathrm{H}(\mathrm{g})]$ always have a positive sign, always have a negative sign, or vary? Explain briefly.

Bryan Li
Bryan Li
Numerade Educator
02:05

Problem 99

A molecule has four electron pairs around a central atom. Explain how the molecule can have a pyramidal structure. How can the molecule have a bent structure? What bond angles are predicted in each case?

Kathleen Pankow
Kathleen Pankow
Numerade Educator
01:50

Problem 100

What is the difference between the electron-pair geometry and the molecular geometry of a molecule? Use the water molecule as an example in your discussion.

Bryan Li
Bryan Li
Numerade Educator
13:23

Problem 101

Bromine plays a role in environmental chemistry. It is, for example, evolved in volcanic eruptions.
(a) The following molecules are important in bromine environmental chemistry: HBr, BrO, HOBr, and OH. Which are odd-electron molecules?
(b) Use bond energies to estimate the energies of three reactions of bromine:
$\mathrm{Br}_{2}(\mathrm{g}) \longrightarrow 2 \mathrm{Br}(\mathrm{g})$
$2 \mathrm{Br}(\mathrm{g})+\mathrm{O}_{2}(\mathrm{g}) \longrightarrow 2 \mathrm{BrO}(\mathrm{g})$
$\mathrm{BrO}(\mathrm{g})+\mathrm{H}_{2} \mathrm{O}(\mathrm{g}) \longrightarrow \mathrm{HOBr}(\mathrm{g})+\mathrm{OH}(\mathrm{g})$
(c) Using bond energies, estimate the standard heat of formation of HOBr $(\mathrm{g})$ from $\mathrm{H}_{2}(\mathrm{g}), \mathrm{O}_{2}(\mathrm{g}),$ and $\mathrm{Br}_{2}(\mathrm{g})$
(d) Are the reactions in parts (b) and (c) exothermic or endothermic?

Kathleen Pankow
Kathleen Pankow
Numerade Educator
04:09

Problem 102

The simple molecule acrylamide, $\mathrm{H}_{2} \mathrm{C}=\mathrm{CHC}(=$
O) $\mathrm{NH}_{2}$, is a known neurotoxin and possible carcinogen. It was a shock to all consumers of potato chips and french fries a few years ago when was found to occur in those products. (Acrylamide arises during the cooking process from a reaction of the sugar glucose and the amino acid asparagine, both naturally found in many foods, $)$.
(a) Draw an electron dot structure for acrylamide, showing any possible resonance structures.
(b) Sketch the molecular structure of acrylamide, showing all unique bond angles.
(c) Indicate which carbon-carbon bond is the stronger of the two.
(d) Is the molecule polar or nonpolar?
(e) The amount of acrylamide found in potato chips is
$1.7 \mathrm{mg} / \mathrm{kg} .$ If a serving of potato chips is $28 \mathrm{g},$ how many moles of acrylamide are you consuming?

Rajesh Singh
Rajesh Singh
Numerade Educator
00:58

Problem 103

Examine the trends in lattice energy in Table $9.3 .$ The value of the lattice energy becomes somewhat more negative on going from NaI to NaBr to NaCl, and all are in the range of -700 to $-800 \mathrm{kJ} / \mathrm{mol}$. Suggest a reason for the observation that the lattice energy of NaF $\left(\Delta E_{\text {latice }}=\right.$.$-926 \mathrm{kJ} / \mathrm{mol})$ is much more negative than those of the other sodium halides.

Carlene Jimenez
Carlene Jimenez
Numerade Educator
04:40

Problem 104

Locate the molecules in the table shown here in the Molecular Models folder on the General Chemistry Now CD-ROM or website. Measure the carbon-carbon bond length in each and complete the table. (Note that the bond lengths are given in angstrom units, where $1 \AA=0.1 \mathrm{nm} .)$.
(TABLE CAN'T COPY)
What relationship between bond order and carboncarbon bond length do you observe?

Bryan Li
Bryan Li
Numerade Educator
06:57

Problem 105

See General Chemistry Now CD-ROM or website Screen
9.18 Molecular Polarity. Use the Molecular Polarity tool on this screen to explore the polarity of molecules.
(a) Is $\mathrm{BF}_{3}$ a polar molecule? Does the molecular polarity change as $\mathrm{F}$ is replaced by $\mathrm{H}$ on $\mathrm{BF}_{3}$ ? Does the polarity change as $\mathrm{F}$ is replaced by $\mathrm{H}$ ? What happens when two
F atoms are replaced by H?
(b) Is $\mathrm{BeCl}_{2}$ a polar molecule? Does the polarity change when $\mathrm{Cl}$ is replaced by $\mathrm{Br}$ ?

Kathleen Pankow
Kathleen Pankow
Numerade Educator
07:51

Problem 106

Locate the following molecules in the Molecular Models folder on the General Chemistry Now CD-ROM or website. In each case, measure unique bond angles and bond lengths and use them to label a sketch of the molecule.
(a) Tylenol (Drugs folder)
(b) $\mathrm{CIF}_{3}$ (Inorganic folder)
(c) Ethylene glycol (Organic Alcohols folder)

Bryan Li
Bryan Li
Numerade Educator