Organic Chemistry

Paula Yurkanis Bruice

Chapter 1

Electronic Structure and Bonding • Acids and Bases - all with Video Answers

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Chapter Questions

Problem 1

Oxygen has three isotopes with mass numbers of $16,17,$ and $18 .$ The atomic number of oxygen is eight. How many protons and neutrons does each of the isotopes have?

Arnelia K

Arnelia K

Numerade Educator

Problem 2

Potassium has an atomic number of 19 and one unpaired electron. What orbital does the unpaired electron occupy?

Arnelia K

Numerade Educator

Problem 3

Write electronic configurations for chlorine (atomic number 17 ), bromine (atomic number 35), and iodine (atomic number 53).

Anthony Han

Numerade Educator

Problem 4

Compare the ground-state electronic configurations of the following atoms, and check the relative positions of the atoms in Table 1.3 on $\mathrm{p}$. 10 .
a. carbon and silicon
b. oxygen and sulfur
c. fluorine and bromine
d. magnesium and calcium

RM

Rangika Munaweera

Numerade Educator

Problem 5

Which of the following has
a. the most polar bond?
$\mathrm{NaI}$ $\quad$ $\mathrm{LiBr}$
b. the least polar bond?
$\mathrm{Cl}_{2}$ $\quad$$\mathrm{KCl}$

Caleb Prus

Numerade Educator

Problem 6

After examining the potential maps for $L$ i. $H, H F,$ and $H_{2},$ answer the following questions:
a. Which compounds are polar?
b. Why does LiH have the largest hydrogen?
c. Which compound has the most positively charged hydrogen?

Caleb Prus

Numerade Educator

Problem 7

Determine the partial negative charge on the oxygen atom in a $\mathrm{C}=$ O bond. The bond length is $1.22 \space\mathrm{A}^{*}$ and the bond dipole moment is $2.30 \mathrm{D}$.
If there were a full negative charge on the oxygen atom, the dipole moment would be
$$\left(4.80 \times 10^{-10} \mathrm{esu}\right)\left(1.22 \times 10^{-8} \mathrm{cm}\right)=5.86 \times 10^{-18} \mathrm{esucm}=5.86 \mathrm{D}$$ Knowing that the dipole moment is $2.30 \mathrm{D}$, we calculate that the partial negative charge on the oxygen atom is about 0.4: $$\frac{2.30}{5.86}=0.39$$

Lottie Adams

Numerade Educator

Problem 8

Use the symbols $\delta+$ and $\delta-$ to show the direction of polarity of the indicated bond in each of the following compounds.
a. $\mathrm{HO}-\mathrm{H}$
b. $\mathrm{F}-\mathrm{Br}$
c. $\mathrm{H}_{3} \mathrm{C}-\mathrm{NH}_{2}$
d. $\mathrm{H}_{3} \mathrm{C}-\mathrm{Cl}$
e. $\mathrm{HO}-\mathrm{Br}$
f. $\mathrm{H}_{3} \mathrm{C}-\mathrm{MgBr}$
$\mathrm{g} \cdot \mathrm{I}-\mathrm{Cl}$
h. $\mathrm{H}_{2} \mathrm{N}-\mathrm{OH}$

Susan Hallstrom

Susan Hallstrom

Numerade Educator

Problem 9

A formal charge is a bookkeeping device. It does not necessarily indicate that the atom has greater or less electron density than other atoms in the molecule without formal charges. You can see this by examining the potential maps for $\mathrm{H}_{2} \mathrm{O}, \mathrm{H}_{3} \mathrm{O}^{+},$ and $\mathrm{HO}^{-}$
a. Which atom bears the formal negative charge in the hydroxide ion?
b. Which atom is the most negative in the hydroxide ion?
c. Which atom bears the formal positive charge in the hydronium ion?
d. Which atom is the most positive in the hydronium ion?

Caleb Prus

Numerade Educator

Problem 10

Draw the Lewis structure for each of the following:
a. $\mathrm{NO}_{3}^{-}$
b. $\mathrm{NO}_{2}^{+}$
c. $N O_{2}^{-}$
d. $\mathrm{CO}_{2}$
e. $\mathrm{HCO}_{3}^{-}$
f. $\mathrm{N}_{2}$
g. $\mathrm{CH}_{3} \mathrm{NH}_{3}^{+}$
h. $^{+} C_{2} H_{5}$
i. $^{-} \mathrm{CH}_{3}$
j. $\mathrm{NaOH}$
k. $\mathrm{NH}_{4} \mathrm{Cl}$
l. $\mathrm{Na}_{2} \mathrm{CO}_{3}$

Joshua Gibson

Numerade Educator

Problem 11

a. Draw two Lewis structures for $\mathrm{C}_{2} \mathrm{H}_{6} \mathrm{O}$. $\quad$ b. Draw three Lewis structures for $\mathrm{C}_{3} \mathrm{H}_{8} \mathrm{O}$
(Hint: The two Lewis structures in part a are constitutional isomers; they have the same atoms, but differ in the way the atoms are connected. The three Lewis structures in part b are also constitutional isomers.)

Anthony Han

Numerade Educator

Problem 12

Expand the following condensed structures to show the covalent bonds and lone-pair electrons:
a. $\mathrm{CH}_{3} \mathrm{NHCH}_{2} \mathrm{CH}_{3}$
b. $\left(\mathrm{CH}_{3}\right)_{2} \mathrm{CHCl}$
c. $\left(\mathrm{CH}_{3}\right)_{2} \mathrm{CHCHO}$
d. $\left(\mathrm{CH}_{3}\right)_{3} \mathrm{C}\left(\mathrm{CH}_{2}\right)_{3} \mathrm{CH}\left(\mathrm{CH}_{3}\right)_{2}$

Joshua Gibson

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Problem 13

Predict whether or not $\mathrm{He}_{2}^{+}$ exists.

Anthony Han

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Problem 14

Indicate the kind of molecular orbital $\left(\sigma, \sigma^{*}, \pi, \text { or } \pi^{*}\right)$ that results when the orbitals are combined as indicated:

Joshua Gibson

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Problem 15

What orbitals are used to form the 10 covalent bonds in propane $\left(\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{CH}_{3}\right) ?$

Caleb Prus

Numerade Educator

Problem 16

The bond angles in $\mathrm{H}_{3} \mathrm{O}^{+}$ are greater than__________ and less than _____________.

Himanshu Kushwaha

Himanshu Kushwaha

Numerade Educator

Problem 17

According to the potential map for the ammonium ion, which atom(s) is (are) most positively charged?

Caleb Prus

Numerade Educator

Problem 18

Compare the potential maps for methane, ammonia, and water. Which is the most polar molecule? Which is the least polar?

Caleb Prus

Numerade Educator

Problem 19

a. Predict the relative lengths and strengths of the bonds in $\mathrm{Cl}_{2}$ and $\mathrm{Br}_{2}$
b. Predict the relative lengths and strengths of the bonds in HF, HCl, and HBr.

Anthony Han

Numerade Educator

Problem 20

Which of the bonds of a carbon-carbon double bond has more effective orbital-orbital overlap, the $\sigma$ bond or the $\pi$ bond?

Anthony Han

Numerade Educator

Problem 21

Why would you expect a $\mathrm{C}-\mathrm{C} \sigma$ bond formed by $s p^{2}-s p^{2}$ overlap to be stronger than a $\sigma$ bond formed by $s p^{3}-s p^{3}$ overlap?

Caleb Prus

Numerade Educator

Problem 22

a. What is the hybridization of each of the carbon atoms in the following compound?
b. What is the hybridization of each of the carbon, oxygen, and nitrogen atoms in the following compounds?

Caleb Prus

Numerade Educator

Problem 23

Describe the orbitals used in bonding and the bond angles in the following compounds. (Hint: see Table 1.7).
$\begin{array}{llllll}\text { a. } \mathrm{BeH}_{2} & \text { b. } \mathrm{BH}_{3} & \text { c. } \mathrm{CCl}_{4} & \text { d. } \mathrm{CO}_{2} & \text { e. HCOOH } & \text { f. } \mathrm{N}_{2}\end{array}$

Caleb Prus

Numerade Educator

Problem 24

Account for the difference in the shape and color of the potential maps for ammonia and the ammonium ion in Section 1.12

Caleb Prus

Numerade Educator

Problem 25

Which of the following molecules would you expect to have a dipole moment of zero? To answer parts $g$ and $h$, you may need to consult your answers to Problem 23 a and b.
a. $\mathrm{CH}_{3} \mathrm{CH}_{3}$
b. $\mathrm{H}_{2} \mathrm{C}=\mathrm{O}$
c. $\mathrm{CH}_{2} \mathrm{Cl}_{2}$
d. $\mathrm{NH}_{3}$
e. $\mathrm{H}_{2} \mathrm{C}=\mathrm{CH}_{2}$
f. $\mathrm{H}_{2} \mathrm{C}=\mathrm{CHBr}$
g. $\mathrm{BeCl}_{2}$
h. $B F_{3}$

Caleb Prus

Numerade Educator

Problem 26

a. Draw the conjugate acid of each of the following:
1. $\mathrm{NH}_{3}$
2. $\mathrm{Cl}^{-}$
3. HO $^{-}$
4. $\mathrm{H}_{2} \mathrm{O}$
b. Draw the conjugate base of each of the following:
1. $\mathrm{NH}_{3}$
2. HBr
3. HNO $_{3}$
4. $\mathrm{H}_{2} \mathrm{O}$

Joshua Gibson

Numerade Educator

Problem 27

a. Write an equation showing $\mathrm{CH}_{3} \mathrm{OH}$ reacting as an acid with $\mathrm{NH}_{3}$ and an equation showing it reacting as a base with HCl.
b. Write an equation showing $\mathrm{NH}_{3}$ reacting as an acid with $\mathrm{HO}^{-}$ and an equation showing it reacting as a base with HBr.

Anthony Han

Numerade Educator

Problem 28

a. Which is a stronger acid, one with a $\mathrm{p} K_{\mathrm{a}}$ of 5.2 or one with a $\mathrm{p} K_{\mathrm{a}}$ of $5.8 ?$
b. Which is a stronger acid, one with an acid dissociation constant of $3.4 \times 10^{-3}$ or one with an acid dissociation constant of $2.1 \times 10^{-4} ?$

Shazia Naz

Numerade Educator

Problem 29

An acid has a $K_{\mathrm{a}}$ of $4.53 \times 10^{-6}$ in water. What is its $K_{\mathrm{cq}} ?\left(\left[\mathrm{H}_{2} \mathrm{O}\right]=55.5 \mathrm{M}\right)$

Anthony Han

Numerade Educator

Problem 30

a. For each of the acid-base reactions in Section $1.17,$ compare the $\mathrm{p} K_{\mathrm{a}}$ values of the acids on either side of the equilibrium arrows and convince yourself that the position of equilibrium is in the direction indicated. (The $p K_{\mathrm{a}}$ values you need can be found in Section 1.17 or in Problem 31.
b. Do the same thing for the equilibria in Section $1.16 .$ (The $\mathrm{p} K_{\mathrm{a}}$ of $^{+} \mathrm{NH}_{4}$ is $9.4 .$ )

Himanshu Kushwaha

Himanshu Kushwaha

Numerade Educator

Problem 31

a. Which is a stronger base, $\mathrm{CH}_{3} \mathrm{COO}^{-}$ or $\mathrm{HCOO}^{-2}$ ? (The $\mathrm{p} K_{\mathrm{a}}$ of $\mathrm{CH}_{3} \mathrm{COOH}$ is 4.8; the
$\left.\mathrm{p} K_{\mathrm{a}} \text { of } \mathrm{HCOOH} \text { is } 3.8 .\right)$
b. Which is a stronger base, $\mathrm{HO}^{-}$ or $\mathrm{NH}_{2}$ ? (The $\mathrm{p} K_{\mathrm{a}}$ of $\mathrm{H}_{2} \mathrm{O}$ is $15.7 ;$ the $\mathrm{p} K_{\mathrm{a}}$ of $\mathrm{NH}_{3}$
36.)
c. Which is a stronger base, $\mathrm{H}_{2} \mathrm{O}$ or $\mathrm{CH}_{3} \mathrm{OH}$ ? (The $\mathrm{p} K_{\mathrm{a}}$ of $\mathrm{H}_{3} \mathrm{O}^{+}$ is $-1.7 ;$ the $\mathrm{p} K_{\mathrm{a}}$ of $\mathrm{CH}_{3} \mathrm{OH}_{2}+\mathrm{is}-2.5 .$

Anthony Han

Numerade Educator

Problem 32

Using the $\mathrm{p} K_{\mathrm{a}}$ values in Section $1.17,$ rank the following species in order of decreasing base strength:

Ryder Mora

Numerade Educator

Problem 33

Calculate the equilibrium constant for the acid-base reactions between the following pairs of reactants.
a. $\mathrm{HCl}+\mathrm{H}_{2} \mathrm{O}$
b. $\mathrm{CH}_{3} \mathrm{COOH}+\mathrm{H}_{2} \mathrm{O}$
c. $\mathrm{CH}_{3} \mathrm{NH}_{2}+\mathrm{H}_{2} \mathrm{O}$
d. $\mathrm{CH}_{3}^{+} \mathrm{NH}_{3}+\mathrm{H}_{2} \mathrm{O}$

Ryder Mora

Numerade Educator

Problem 34

For each of the following compounds, indicate which is the stronger acid:
a. $\mathrm{CH}_{3} \mathrm{OCH}_{2} \mathrm{CH}_{2} \mathrm{OH} \quad$ or $\quad \mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{CH}_{2} \mathrm{CH}_{2} \mathrm{OH}$
b. $\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{CH}_{2} \mathrm{NH}_{3}$ or $\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{CH}_{2} \mathrm{OH}_{2}$
c. $\mathrm{CH}_{3} \mathrm{OCH}_{2} \mathrm{CH}_{2} \mathrm{CH}_{2} \mathrm{OH} \quad$ or $\quad \mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{OCH}_{2} \mathrm{CH}_{2} \mathrm{OH}$

Anthony Han

Numerade Educator

Problem 35

List the following compounds in order of decreasing acidity:

Joshua Gibson

Numerade Educator

Problem 36

For each of the following compounds, indicate which is the stronger base:

Joshua Gibson

Numerade Educator

Problem 37

HCI is a weaker acid than HBr. Why, then, is $\mathrm{ClCH}_{2} \mathrm{COOH}$ a stronger acid than $\mathrm{BrCH}_{2} \mathrm{COOH} ?$
To compare the acidities of HCI and HBr, we need to compare the stabilities of $\mathrm{Cl}^{-}$ and $\mathrm{Br}^{-}$. Because we know that size is more important than electronegativity in determining stability, we know that $\mathrm{Br}^{-}$ is more stable than $\mathrm{Cl}^{-}$. Therefore, $\mathrm{HBr}$ is a stronger acid than HCl. In comparing the acidities of the two carboxylic acids, we need to compare the stabilities of $\mathrm{RCOO}^{-}$ and $\mathrm{R}^{\prime} \mathrm{COO}^{-}$. (An $\mathrm{O}-\mathrm{H}$ bond is broken in both compounds.) Therefore, the only factor to be considered is the electronegativities of the atoms that are pulling electrons away from the oxygen atom in the conjugate bases. Because $\mathrm{Cl}$ is more electronegative than $\mathrm{Br}, \mathrm{Cl}$ is better at inductive electron withdrawal. Thus, it is better at stabilizing the base that is formed when the proton leaves.

Ryder Mora

Numerade Educator

Problem 38

a. Which of the halide ions $\left(\mathrm{F}^{-}, \mathrm{Cl}^{-}, \mathrm{Br}^{-}, \mathrm{I}^{-}\right)$ is the strongest base?
b. Which is the weakest base?

Anthony Han

Numerade Educator

Problem 39

a. Which is more electronegative, oxygen or sulfur?
b. Which is a stronger acid, $\mathrm{H}_{2} \mathrm{O}$ or $\mathrm{H}_{2} \mathrm{S}$ ?
c. Which is a stronger acid, $\mathrm{CH}_{3} \mathrm{OH}$ or $\mathrm{CH}_{3} \mathrm{SH} ?$

Shazia Naz

Numerade Educator

Problem 40

Using the table of $\mathrm{p} K_{\mathrm{a}}$ values given in Appendix $\mathrm{II}$, answer the following:
a. Which is the most acidic organic compound in the table?
b. Which is the least acidic organic compound in the table?
c. Which is the most acidic carboxylic acid in the table?
d. Which is more electronegative, an $s p^{3}$ hybridized oxygen or an $s p^{2}$ hybridized oxygen? (Hint: Pick a compound in Appendix II with a hydrogen attached to an $s p^{2}$ oxygen and one with a hydrogen attached to an $s p^{3}$ oxygen, and compare their $\mathrm{p} K_{\mathrm{a}}$ values.)
e. What are the relative electronegativities of $s p^{3}, s p^{2},$ and $s p$ hybridized nitrogen atoms?
f. What are the relative electronegativities of $s p^{3}, s p^{2},$ and $s p$ hybridized carbon atoms?
g. Which is more acidic, HNO $_{3}$ or $\mathrm{HNO}_{2}$ ? Why?

Shazia Naz

Numerade Educator

Problem 41

Which compound would you expect to be a stronger acid? Why?

Joshua Gibson

Numerade Educator

Problem 42

Draw resonance contributors for the following compounds:

Joshua Gibson

Numerade Educator

Problem 43

As long as the pH is greater than__________, more than $50 \%$ of a protonated amine with a $\mathrm{p} K_{\mathrm{a}}$ of 10.4 will be in its neutral, nonprotonated form.

Anthony Han

Numerade Educator

Problem 44

a. At what pH will $99 \%$ of a compound with a $\mathrm{p} K_{\mathrm{a}}$ of 8.4 be in its basic form?
b. At what $\mathrm{pH}$ will $91 \%$ of a compound with a $\mathrm{p} K_{\mathrm{a}}$ of 3.7 be in its acidic form?
c. At what $\mathrm{pH}$ will $9 \%$ of a compound with a $\mathrm{p} K_{\mathrm{a}}$ of 5.9 be in its basic form?
d. At what pH will $50 \%$ of a compound with a $\mathrm{p} K_{\mathrm{a}}$ of 7.3 be in its basic form?
e. At what pH will $1 \%$ of a compound with a $\mathrm{p} K_{\mathrm{a}}$ of 7.3 be in its acidic form?
If $99 \%$ is in the basic form and $1 \%$ is in the acidic form, the Henderson-Hasselbalch equation becomes $$\begin{aligned}
\mathrm{p} K_{\mathrm{a}} &=\mathrm{pH}+\log \frac{1}{99} \\
8.4 &=\mathrm{pH}+\log .01 \\
8.4 &=\mathrm{pH}-2.0 \\
\mathrm{pH} &=10.4
\end{aligned}$$ There is a faster way to get the answer:
If about 100 times more compound is present in the basic form than in the acidic form, the pH will be two units more basic than the $\mathrm{pK}_{\mathrm{a}}$. Thus, $\mathrm{pH}=8.4+2.0=10.4$ If $91 \%$ is in the acidic form and $9 \%$ is in the basic form, there is about 10 times more compound present in the acidic form. Therefore, the $\mathrm{pH}$ is one unit more acidic than the $\mathrm{p} K_{\mathrm{a}} .$ Thus, $\mathrm{pH}=3.7-1.0=2.7$

Shazia Naz

Numerade Educator

Problem 45

a. Indicate whether a carboxylic acid (RCOOH) with a $\mathrm{p} K_{\mathrm{a}}$ of 5 will be mostly charged or mostly neutral in solutions with the following pH values:
1. $\mathrm{pH}=1$
2. $\mathrm{pH}=3$
3. $\mathrm{pH}=5$
4. $\mathrm{pH}=7$
5. $\mathrm{pH}=9$
6. $\mathrm{pH}=11$
7. $\mathrm{pH}=13$
b. Answer the same question for a protonated amine $\left(\mathrm{R} \mathrm{NH}_{3}\right)$ with a $\mathrm{p} K_{\mathrm{a}}$ of 9.
c. Answer the same question for an alcohol (ROH) with a $\mathrm{p} K_{\mathrm{a}}$ of 15.

Caleb Prus

Numerade Educator

Problem 46

For each compound in 1 and 2, indicate the pH at which
a. $50 \%$ of the compound will be in a form that possesses a charge.
b. more than $99 \%$ of the compound will be in a form that possesses a charge.
1. $\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{COOH}\left(\mathrm{p} K_{\mathrm{a}}=4.9\right)$
2. $\mathrm{CH}_{3} \mathrm{NH}_{3}\left(\mathrm{p} K_{\mathrm{a}}=10.7\right)$

Anthony Han

Numerade Educator

Problem 47

For each of the following compounds, shown in their acidic forms, draw the form in which it will predominate in a solution of $\mathrm{pH}=7$ :
a. $\mathrm{CH}_{3} \mathrm{COOH}\left(\mathrm{p} K_{\mathrm{a}}=4.76\right)$
b. $\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{NH}_{3}\left(\mathrm{p} K_{\mathrm{a}}=11.0\right)$
c. $\mathrm{H}_{3} \mathrm{O}^{+}\left(\mathrm{p} K_{\mathrm{a}}=-1.7\right)$
d. $\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{OH}\left(\mathrm{p} K_{\mathrm{a}}=15.9\right)$
e. $\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{OH}_{2}\left(\mathrm{p} K_{\mathrm{a}}=-2.5\right)$
f. $\mathrm{N^{+}H}_{4}\left(\mathrm{p} K_{\mathrm{a}}=9.4\right)$
g. $\mathrm{HC} \equiv \mathrm{N}\left(\mathrm{p} K_{\mathrm{a}}=9.1\right)$
h. $\mathrm{HNO}_{2}\left(\mathrm{p} K_{\mathrm{a}}=3.4\right)$
i. $\mathrm{HNO}_{3}\left(\mathrm{p} K_{\mathrm{a}}=-1.3\right)$
j. $\operatorname{HBr}\left(\mathrm{p} K_{\mathrm{a}}=-9\right)$

Joshua Gibson

Numerade Educator

Problem 48

What is the product of each of the following reactions?
a. $\mathrm{ZnCl}_{2}+\mathrm{CH}_{3} \mathrm{OH} \rightleftharpoons$
b. $\mathrm{FeBr}_{3}+\mathrm{Br}^{-} \rightleftharpoons$
c. $A I C I_{3}+C I^{-} \equiv$
d.

Joshua Gibson

Numerade Educator

Problem 49

Show how each of the following compounds reacts with $\mathrm{HO}^{-}$ :
a. $\mathrm{CH}_{3} \mathrm{OH}$
b. $^{+} N H_{4}$
c.
d. $B F_{3}$
$\mathrm{e} .^{+} \mathrm{CH}_{3}$
f. $\operatorname{Fe} \mathrm{Br}_{3}$
g. $\mathrm{AlCl}_{3}$
h. $\mathrm{CH}_{3} \mathrm{COOH}$

Joshua Gibson

Numerade Educator

Problem 50

Draw a Lewis structure for each of the following species:
a. $\quad \mathrm{H}_{2} \mathrm{CO}_{3}$
b. $\mathrm{CO}_{3}^{2-}$
c. $\quad \mathrm{H}_{2} \mathrm{CO}$
d. $\quad \mathrm{N}_{2} \mathrm{H}_{4}$
e. $\quad \mathrm{CH}_{3} \mathrm{NH}_{2}$
f. $\quad \mathrm{CH}_{3} \mathrm{N}_{2}^{+}$
g. $\mathrm{CO}_{2}$
h. $\mathrm{NO}^{+}$
i. $\quad \mathrm{H}_{2} \mathrm{NO}^{-}$

Joshua Gibson

Numerade Educator

Problem 51

Give the hybridization of the central atom of each of the following species, and tell whether the bond arrangement around it is linear, trigonal planar, or tetrahedral:
a. $\quad \mathrm{NH}_{3}$
b. $\quad \mathrm{BH}_{3}$
c. $\quad-\mathrm{CH}_{3}$
d. $\quad \mathrm{CH}_{3}$
e. $^{+} \mathrm{NH}_{4}$
f. $^{+} \mathrm{CH}_{3}$
g. HCN
h. $\quad C\left(C H_{3}\right)_{4}$
i. $\quad \mathrm{H}_{3} \mathrm{O}^{+}$

Joshua Gibson

Numerade Educator

Problem 52

Draw the condensed structure of a compound that contains only carbon and hydrogen atoms and that has
a. three $s p^{3}$ hybridized carbons.
b. one $s p^{3}$ hybridized carbon and two $s p^{2}$ hybridized carbons.
c. two $s p^{3}$ hybridized carbons and two $s p$ hybridized carbons.

Anthony Han

Numerade Educator

Problem 53

Predict the indicated bond angles:
a. the $\mathrm{C}-\mathrm{N}-\mathrm{H}$ bond angle in $\left(\mathrm{CH}_{3}\right)_{2} \mathrm{NH}$
b. the $\mathrm{C}-\mathrm{N}-\mathrm{C}$ bond angle in $\left(\mathrm{CH}_{3}\right)_{2} \mathrm{NH}$
c. the $\mathrm{C}-\mathrm{N}-\mathrm{C}$ bond angle in $\left(\mathrm{CH}_{3}\right)_{2}^{+} \mathrm{NH}_{2}$
d. the $\mathrm{C}-\mathrm{O}-\mathrm{C}$ bond angle in $\mathrm{CH}_{3} \mathrm{OCH}_{3}$
e. the $\mathrm{C}-\mathrm{O}-\mathrm{H}$ bond angle in $\mathrm{CH}_{3} \mathrm{OH}$
f. the $\mathrm{H}-\mathrm{C}-\mathrm{H}$ bond angle in $\mathrm{H}_{2} \mathrm{C}=\mathrm{O}$
g. the $\mathrm{F}-\mathrm{B}-\mathrm{F}$ bond angle in $\mathrm{BF}_{4}$
h. the $C-C-N$ bond angle in $C H_{3} C \equiv N$
i. the $\mathrm{C}-\mathrm{C}-\mathrm{N}$ bond angle in $\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{NH}_{2}$

Himanshu Kushwaha

Himanshu Kushwaha

Numerade Educator

Problem 54

Give each atom the appropriate formal charge:

Lottie Adams

Numerade Educator

Problem 55

Draw the ground-state electronic configuration for:
a. $\mathrm{Ca}$
b. $C a^{2+}$
c. $A r$
d. $\mathrm{Mg}^{2+}$

Joshua Gibson

Numerade Educator

Problem 56

Write the Kekulé structure for each of the following compounds:
a. $\quad \mathrm{CH}_{3} \mathrm{CHO}$
b. $\quad \mathrm{CH}_{3} \mathrm{OCH}_{3}$
c. $\quad \mathrm{CH}_{3} \mathrm{COOH}$
d. $\left(\mathrm{CH}_{3}\right)_{3} \mathrm{COH}$
e. $\quad \mathrm{CH}_{3} \mathrm{CH}(\mathrm{OH}) \mathrm{CH}_{2} \mathrm{CN}$
f. $\quad\left(\mathrm{CH}_{3}\right)_{2} \mathrm{CHCH}\left(\mathrm{CH}_{3}\right) \mathrm{CH}_{2} \mathrm{C}\left(\mathrm{CH}_{3}\right)_{3}$

Joshua Gibson

Numerade Educator

Problem 57

Show the direction of the dipole moment in each of the following bonds (use the electronegativities given in Table 1.3 ):
a. $\quad \mathrm{CH}_{3}-\mathrm{Br}$
b. $\quad \mathrm{CH}_{3}-\mathrm{Li}$
c. $\mathrm{HO}-\mathrm{NH}_{2}$
d. $\mathrm{I}-\mathrm{Br}$
e. $\quad \mathrm{CH}_{3}-\mathrm{OH}$
f. $\quad\left(\mathrm{CH}_{3}\right)_{2} \mathrm{N}-\mathrm{H}$

Anthony Han

Numerade Educator

Problem 58

What is the hybridization of the indicated atom in each of the following molecules?

Joshua Gibson

Numerade Educator

Problem 59

a. Which of the indicated bonds in each molecule is shorter?
b. Indicate the hybridization of the $C, O,$ and $N$ atoms in each of the molecules.

Lottie Adams

Numerade Educator

Problem 60

For each of the following compounds, draw the form in which it will predominate at $\mathrm{pH}=3, \mathrm{pH}=6, \mathrm{pH}=10,$ and $\mathrm{pH}=14$.
a. $\quad \mathrm{CH}_{3} \mathrm{COOH}$
$p K_{a}=4.8$
b. $\quad \mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{NH}_{3}$
$\mathbf{p} K_{\mathrm{a}}=11.0$
c. $\quad \mathrm{CF}_{3} \mathrm{CH}_{2} \mathrm{OH}$
$p K_{a}=12.4$

Anthony Han

Numerade Educator

Problem 61

Which of the following molecules have tetrahedral bond angles?
$$\mathrm{H}_{2} \mathrm{O} \quad \mathrm{H}_{3} \mathrm{O}^{+} \quad^{+} \mathrm{CH}_{3} \quad \mathrm{BF}_{3} \quad \mathrm{NH}_{3} \quad^{+} \mathrm{NH}_{4} \quad \mathrm{CH}_{3}$$

Joshua Gibson

Numerade Educator

Problem 62

Do the $s p^{2}$ hybridized carbons and the indicated atoms lie in the same plane?

Anthony Han

Numerade Educator

Problem 63

Give the products of the following acid-base reactions, and indicate whether reactants or products are favored at equilibrium (use the p $K_{\mathrm{a} \text { values that are given in Section } 1.17):}$

Joshua Gibson

Numerade Educator

Problem 64

For each of the following molecules, indicate the hybridization of each carbon atom and give the approximate values of all the bond angles:
a. $\quad \mathrm{CH}_{3} \mathrm{C} \equiv \mathrm{CH}$
b. $\quad \mathrm{CH}_{3} \mathrm{CH}=\mathrm{CH}_{2}$
c. $\quad \mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{CH}_{3}$

Anthony Han

Numerade Educator

Problem 65

Estimate the $p K_{\mathrm{a}}$ value of each of the following acids without using a calculator (i.e., between 3 and 4, between 9 and 10, etc.):
1. nitrous acid $\left(\mathrm{HNO}_{2}\right), K_{\mathrm{a}}=4.0 \times 10^{-4}$
2. nitric acid $\left(\mathrm{HNO}_{3}\right), K_{\mathrm{a}}=22$
3. bicarbonate $\left(\mathrm{HCO}_{3}^{-}\right), K_{\mathrm{a}}=6.3 \times 10^{-11}$
4. hydrogen cyanide (HCN), $K_{\mathrm{a}}=7.9 \times 10^{-10}$
5. formic acid (HCOOH), $K_{\mathrm{a}}=2.0 \times 10^{-4}$
b. Determine the $\mathrm{p} K_{\mathrm{a}}$ values, using a calculator.
c. Which is the strongest acid?

Joshua Gibson

Numerade Educator

Problem 66

a. List the following carboxylic acids in order of decreasing acidity:
1. $\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{CH}_{2} \mathrm{COOH}$
$K_{\mathrm{a}}=1.52 \times 10^{-5}$
2. $\quad \mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{CHCOOH}$
$\mathrm{Cl}$
$K_{\mathrm{a}}=1.39 \times 10^{-3}$
3. $\mathrm{ClCH}_{2} \mathrm{CH}_{2} \mathrm{CH}_{2} \mathrm{COOH}$
$K_{\mathrm{a}}=2.96 \times 10^{-5}$
4. $\mathrm{CH}_{3} \mathrm{CHCH}_{2} \mathrm{COOH}$
$$
\mathrm{Cl}
$$
$K_{\mathrm{a}}=8.9 \times 10^{-5}$
b. How does the presence of an electronegative substituent such as $\mathrm{Cl}$ affect the acidity of a carboxylic acid?
c. How does the location of the substituent affect the acidity of a carboxylic acid?

Anthony Han

Numerade Educator

Problem 67

Draw a Lewis structure for each of the following species:
a. $\mathrm{CH}_{3} \mathrm{N}_{2}$
b. $\mathrm{CH}_{2} \mathrm{N}_{2}$
c. $N_{3}^{-}$
d. $\mathrm{N}_{2} \mathrm{O}$ (arranged $\mathrm{NNO}$ )

Anthony Han

Numerade Educator

Problem 68

For each of the following pairs of reactions, indicate which one has the more favorable equilibrium constant (that most favors products):
1. $\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{OH}+\mathrm{NH}_{3} \leftrightharpoons \mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{O}^{-}+\mathrm{NH}_{4}$
Or
$\mathrm{CH}_{3} \mathrm{OH}+\mathrm{NH}_{3} \leftrightharpoons \mathrm{CH}_{3} \mathrm{O}^{-}+\mathrm{NH}_{4}$
2. $\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{OH}+\mathrm{NH}_{3} \leftrightharpoons \mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{O}^{-}+\mathrm{NH}_{4}$
or
$\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{OH}+\mathrm{CH}_{3} \mathrm{NH}_{2} \leftrightharpoons \mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{O}^{-}+\mathrm{CH}_{3} \mathrm{NH}_{3}$
b. Which of the four reactions has the most favorable equilibrium constant?

Ryder Mora

Numerade Educator

Problem 69

The following compound has two isomers:
$$\mathrm{ClCH}=\mathrm{CHCl}$$
One isomer has a dipole moment of 0 D, and the other has a dipole moment of 2.95 D. Propose structures for the two isomers that are consistent with these data.

Anthony Han

Numerade Educator

Problem 70

Knowing that $\mathrm{pH}+\mathrm{pOH}=14$ and that the concentration of water in a solution of water is $55.5 \mathrm{M}$, show that the $\mathrm{p} K_{\mathrm{a}}$ of water is 15.7. (Hint: pOH = - log[HO 7.)

Anthony Han

Numerade Educator

Problem 71

Water and diethyl ether are immiscible liquids. Charged compounds water, and uncharged compounds dissolve in ether.
$$\mathrm{C}_{6} \mathrm{H}_{11} \mathrm{COOH} \text { has a } \mathrm{p} K_{\mathrm{a}} \text { of } 4.8 \text { and } \mathrm{C}_{6} \mathrm{H}_{11} \mathrm{NH}_{3} \text { has a } \mathrm{p} K_{\mathrm{a}} \text { of } 10.7$$
a. What pH would you make the water layer in order to cause both compounds to dissolve in it?
b. What pH would you make the water layer in order to cause the acid to dissolve in the water layer and the amine to dissolve in the ether layer?
c. What pH would you make the water layer in order to cause the acid to dissolve in the ether layer and the amine to dissolve in the water layer?

Anthony Han

Numerade Educator

Problem 72

How could you separate a mixture of the following compounds? The reagents available to you are water, ether, $1.0 \mathrm{M} \mathrm{HCl}$, and 1.0 M NaOH. (Hint: See problem 70.)

Shazia Naz

Numerade Educator

Problem 73

Using molecular orbital theory, explain why shining light on $\mathrm{Br}_{2}$ causes it to break apart into atoms, but shining light on $\mathrm{H}_{2}$ does not break the molecule apart.

Caleb Prus

Numerade Educator

Problem 74

$$\text { Show that } K_{\mathrm{cq}}=\frac{K_{\mathrm{a}} \text { reactant acid }}{K_{\mathrm{a}} \text { product acid }}=\frac{[\text { products }]}{[\text { reactants }]}$$

Ryder Mora

Numerade Educator

Problem 75

Carbonic acid has $a p K_{\mathrm{a}}$ of 6.1 at physiological temperature. Is the carbonic acid/bicarbonate buffer system that maintains the pH of the blood at 7.3 better at neutralizing excess acid or excess base?

Anthony Han

Numerade Educator

Problem 76

a. If an acid with a $\mathrm{p} K_{\mathrm{a}}$ of 5.3 is in an aqueous solution of $\mathrm{pH}$ 5.7, what percentage of the acid is present in the acidic form?
b. At what pH will $80 \%$ of the acid exist in the acidic form?

Shazia Naz

Numerade Educator

Problem 77

Calculate the pH values of the following solutions:
a. a $1.0 \mathrm{M}$ solution of acetic acid $\left(\mathrm{p} K_{\mathrm{a}}=4.76\right)$
b. a $0.1 \mathrm{M}$ solution of protonated methylamine $\left(\mathrm{p} K_{\mathrm{a}}=10.7\right)$
c. a solution containing $0.3 \mathrm{M} \mathrm{HCOOH}$ and $0.1 \mathrm{M} \mathrm{HCOO}^{-}\left(\mathrm{p} K_{\mathrm{a}} \text { of } \mathrm{HCOOH}=3.76\right)$

Anthony Han

Numerade Educator