Essential Organic Chemistry

Paula Yurkanis Bruice

Chapter 2

Acids and Bases: Central to Understanding Organic Chemistry - all with Video Answers

Educators

Chapter Questions

Problem 1

Which of the following are not acids?
$$
\begin{array}{lllll}
\mathrm{CH}_{3} \mathrm{COOH} & \mathrm{CO}_{2} & \mathrm{HNO}_{2} & \mathrm{HCOOH} & \mathrm{CCl}_{4}
\end{array}
$$

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Problem 2

Draw the products of the acid-base reaction when
a. $\mathrm{HCl}$ is the acid and $\mathrm{NH}_{3}$ is the base.
b. $\mathrm{H}_{2} \mathrm{O}$ is the acid and $-\mathrm{NH}_{2}$ is the base.

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Problem 3

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

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Problem 4

a. Which is a stronger acid, one with a p $K_{\mathrm{a}}$ of $5.2$ or one with a 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 $2.1 \times 10^{-4} ?$

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Problem 5

Butyric acid, the compound responsible for the unpleasant odor and taste of sour milk, has a p $K_{\text {a }}$ value of $4.82 .$ Vitamin C has a p $K_{\mathrm{a}}$ value of $4.17 .$ Is butyric acid a stronger acid or a weaker acid than vitamin C?

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Problem 6

Antacids are compounds that neutralize stomach acid. Write the equations that show how Milk of Magnesia, Alka-Seltzer, and Tums remove excess acid.
a. Milk of Magnesia: $\mathrm{Mg}(\mathrm{OH})_{2}$
b. Alka-Seltzer: $\mathrm{KHCO}_{3}$ and $\mathrm{NaHCO}_{3}$
c. Tums: $\mathrm{CaCO}_{3}$

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Problem 7

Are the following body fluids acidic or basic?
a. bile $(\mathrm{pH}=8.4)$
b. urine $(\mathrm{pH}=5.9)$
c. spinal fluid $(\mathrm{pH}=7.4)$

Shazia Naz

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Problem 8

Draw the conjugate acid of each of the following:
a. $\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{OH}$
b. $\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{O}^{-}$
c. $\mathrm{CH}_{3} \mathrm{O}^{-}$
d. $\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{NH}_{2}$

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Problem 9

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

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Problem 10

Estimate the $\mathrm{p} K_{\mathrm{a}}$ values of the following compounds:
$$
\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{CH}_{2} \mathrm{NH}_{2} \quad \mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{CH}_{2} \mathrm{OH} \quad \mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{COOH} \quad \mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{CH}_{2} \mathrm{NH}_{3}
$$

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Problem 11

a. Which is a stronger base, $\mathrm{CH}_{3} \mathrm{COO}^{-}$or $\mathrm{HCOO}^{-}$? (The $\mathrm{p} K_{\mathrm{a}}$ of $\mathrm{CH}_{3} \mathrm{COOH}$ is $4.8$; the $\mathrm{p} K_{\mathrm{a}}$ of $\mathrm{HCOOH}$ is $3.8$.)
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 p $K_{\mathrm{a}}$ of $\mathrm{NH}_{3}$ is $36 .$ )
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 $\mathrm{CH}_{3} \mathrm{OH}_{2}$ is $-2.5 .$ )

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Problem 12

Using the $\mathrm{p} K_{\mathrm{a}}$ values in Section 2.3, rank the following species in order from strongest base to weakest base:

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Problem 13

Does methanol behave as an acid or a base when it reacts with methylamine?

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Problem 14

a. For each of the acid-base reactions in Section $2.3$, compare the $\mathrm{p} K_{\mathrm{a}}$ values of the acids on either side of the equilibrium arrows to prove that the equilibrium lies in the direction indicated. (The $\mathrm{p} K_{\mathrm{a}}$ values you need can be found in Section $2.3$ or in Problem 11.)
b. Do the same for the acid-base reactions in Section $2.1 .$

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Problem 15

Ethyne has a p $K_{\mathrm{a}}$ value of 25, water has a $\mathrm{p} K_{\mathrm{a}}$ value of $15.7$, and ammonia $\left(\mathrm{NH}_{3}\right)$ has a $\mathrm{p} K_{\mathrm{a}}$ value of 36 . Draw the equation, showing equilibrium arrows that indicate whether reactants or products are favored, for the acid-base reaction of ethyne with
a. $\mathrm{HO}^{-}$.
b. $-\mathrm{NH}_{2}$.
c. Which would be a better base to use if you wanted to remove a proton from ethyne, $\mathrm{HO}^{-}$or ${ }^{-} \mathrm{NH}_{2}$ ?

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Problem 16

Which of the following bases can remove a proton from acetic acid in a reaction that favors products?
$$
\begin{array}{llllll}
\mathrm{HO}^{-} & \mathrm{CH}_{3} \mathrm{NH}_{2} & \mathrm{HC} \equiv \mathrm{C}^{-} & \mathrm{CH}_{3} \mathrm{OH} & \mathrm{H}_{2} \mathrm{O} & \mathrm{Cl}^{-}
\end{array}
$$

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Problem 17

List the ions $\left(\mathrm{CH}_{3}, \mathrm{NH}_{2}, \mathrm{HO}^{-}\right.$, and $\left.\mathrm{F}\right)$ in order from most basic to least basic.

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Problem 18

List the carbanions shown in the margin in order from most basic to least basic.

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Problem 19

Which is a stronger acid?

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Problem 20

a. Draw the products of the following reactions:
A $\mathrm{HC} \equiv \mathrm{CH}+\mathrm{CH}_{3} \overline{\mathrm{C}} \mathrm{H}_{2} \rightleftharpoons$
B $\mathrm{H}_{2} \mathrm{C}=\mathrm{CH}_{2}+\mathrm{HC} \equiv \mathrm{C}^{-} \rightleftharpoons$
C $\mathrm{CH}_{3} \mathrm{CH}_{3}+\mathrm{H}_{2} \mathrm{C}=\overline{\mathrm{C}} \mathrm{H} \rightleftharpoons$
b. Which of the reactions favor formation of the products?

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Problem 21

List the halide ions $\left(\mathrm{F}^{-}, \mathrm{Cl}^{-}, \mathrm{Br}^{-}\right.$, and $\left.\mathrm{I}^{-}\right)$in order from strongest base to weakest base.

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Problem 22

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 $\mathrm{CH}_{3} \mathrm{SH}$ ?

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Problem 23

Which is a stronger acid?
a. $\mathrm{HCl}$ or $\mathrm{HBr}$
b. $\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{CH}_{2} \mathrm{NH}_{3}$ or $\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{CH}_{2} \mathrm{OH}_{2}$

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Problem 24

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

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Problem 25

Which is a stronger base?
a. $\mathrm{H}_{2} \mathrm{O}$ or $\mathrm{HO}^{-}$
b. $\mathrm{H}_{2} \mathrm{O}$ or $\mathrm{NH}_{3}$
c. $\mathrm{CH}_{3} \mathrm{CO}^{-}$or $\mathrm{CH}_{3} \mathrm{O}^{-}$
d. $\mathrm{CH}_{3} \mathrm{O}^{-}$or $\mathrm{CH}_{3} \mathrm{~S}^{-}$

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Problem 26

Which is a stronger acid?
a. $\mathrm{CH}_{3} \mathrm{OCH}_{2} \mathrm{CH}_{2} \mathrm{OH}$ or $\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{CH}_{2} \mathrm{CH}_{2} \mathrm{OH}$
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. $\mathrm{CH}_{3} \mathrm{OCH}_{2} \mathrm{CH}_{2} \mathrm{CH}_{2} \mathrm{OH}$ or $\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{OCH}_{2} \mathrm{CH}_{2} \mathrm{OH}$
d.
<smiles>CC(=O)CO</smiles>

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Problem 27

Which is a stronger base?

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Problem 28

If $\mathrm{HCl}$ is a weaker acid than $\mathrm{HBr}$, why is $\mathrm{ClCH}_{2} \mathrm{COOH}$ a stronger acid than $\mathrm{BrCH}_{2} \mathrm{COOH}$ ?
Solution To compare the acidities of $\mathrm{HCl}$ and $\mathrm{HBr}$, we need to compare the stabilities of their conjugate bases, $\mathrm{Cl}^{-}$and $\mathrm{Br}^{-}$. (Notice that an $\mathrm{H}-\mathrm{Cl}$ bond breaks in one compound and an $\mathrm{H}$-Br bond breaks in the other.) 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 $\mathrm{HCl}$.

In comparing the acidities of the two carboxylic acids, we again need to compare the stabilities of their conjugate bases, $\mathrm{ClCH}_{2} \mathrm{COO}^{-}$and $\mathrm{BrCH}_{2} \mathrm{COO}^{-}$. (Notice that an $\mathrm{O}-\mathrm{H}$ bond breaks in both compounds.) The only way the conjugate bases differ is in the electronegativity of the atom that is drawing electrons away from the negatively charged oxygen. Because $\mathrm{Cl}$ is more electronegative than $\mathrm{Br}, \mathrm{Cl}$ exerts greater inductive electron withdrawal. Thus, it has a greater stabilizing effect on the base that is formed when the proton leaves, so the chloro-substituted compound is the stronger acid.

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Problem 29

Fosamax has six acidic groups. The structure of the active form of the drug is shown in the box. (Notice that the phosphorus atom in Fosamax and the sulfur atom in Problem 30 can be surrounded by more than eight electrons since $P$ and $S$ are below the second row of the periodic table.)
a. The $\mathrm{OH}$ groups bonded to phosphorus are the strongest acids of the six groups. Why?
b. Which of the remaining four groups is the weakest acid?

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Problem 30

Which is a stronger acid? Why?

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Problem 31

For each of the following compounds (shown in their acidic forms), write the form that will predominate in a solution of $\mathrm{pH}=5.5$ :
a. $\mathrm{CH}_{3} \mathrm{COOH}\left(\mathrm{p} K_{\mathrm{a}}=4.76\right)$
e. ${ }^{+} \mathrm{NH}_{4}\left(\mathrm{p} K_{\mathrm{a}}=9.4\right)$
b. $\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{NH}_{3}\left(\mathrm{p} K_{\mathrm{a}}=11.0\right)$
f. $\mathrm{HC} \equiv \mathrm{N}\left(\mathrm{p} K_{\mathrm{a}}=9.1\right)$
c. $\mathrm{H}_{3} \mathrm{O}^{+}\left(\mathrm{p} K_{\mathrm{a}}=-1.7\right)$
g. $\mathrm{HNO}_{2}\left(\mathrm{p} K_{\mathrm{a}}=3.4\right)$
d. $\operatorname{HBr}\left(\mathrm{p} K_{\mathrm{a}}=-9\right)$
h. $\mathrm{HNO}_{3}\left(\mathrm{p} K_{\mathrm{a}}=-1.3\right)$

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Problem 32

a. Indicate whether a carboxylic acid (RCOOH) with a p $K_{\mathrm{a}}$ value of $4.5$ will have more charged molecules or more neutral molecules in a solution with the following $\mathrm{pH}$ :
1. $\mathrm{pH}=1$
3. $\mathrm{pH}=5$
5. $\mathrm{pH}=10$
2. $\mathrm{pH}=3$
4. $\mathrm{pH}=7$
6. $\mathrm{pH}=13$
b. Answer the same question for a protonated amine $\left(\mathrm{RNH}_{3}\right)$ with a $\mathrm{p} K_{\mathrm{a}}$ value of $9 .$
c. Answer the same question for an alcohol $(\mathrm{ROH})$ with a p $K_{\mathrm{a}}$ value of 15 .

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Problem 33

A naturally occurring amino acid such as alanine has a group that is a carboxylic acid and a group that is a protonated amine. The $\mathrm{p} K_{\mathrm{a}}$ values of the two groups are shown.
a. If the $\mathrm{p} K_{\mathrm{a}}$ value of carboxylic acid such as acetic acid is about 5 (see Table 2.1), then why is the $\mathrm{p} K_{\mathrm{a}}$ value of the carboxylic acid group of alanine so much lower?
b. Draw the structure of alanine in a solution at $\mathrm{pH}=0$.
c. Draw the structure of alanine in a solution at physiological $\mathrm{pH}(\mathrm{pH}$. 4).
d. Draw the structure of alanine in a solution at $\mathrm{pH}=12$.
e. Is there a pH at which alanine will be uncharged (that is, neither group will have a charge)?

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Problem 34

Water and ether are immiscible liquids. Charged compounds dissolve in water and uncharged compounds dissolve in ether (Section 3.7). Given that $\mathrm{C}_{6} \mathrm{H}_{11} \mathrm{COOH}$ has a $\mathrm{p} K_{\mathrm{a}}=4.8$ and $\mathrm{C}_{6} \mathrm{H}_{11} \mathrm{NH}_{3}$ has a $\mathrm{p} K_{\mathrm{a}}=10.7$, answer the following:
a. What $\mathrm{pH}$ would you make the water layer in order to cause both compounds to dissolve in it?
b. What $\mathrm{pH}$ 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 $\mathrm{pH}$ 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?

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Problem 35

Write the equation that shows how a buffer made by dissolving $\mathrm{CH}_{3} \mathrm{COOH}$ and $\mathrm{CH}_{3} \mathrm{COO}^{-} \mathrm{Na}^{+}$ in water prevents the $\mathrm{pH}$ of a solution from changing appreciably when
a. a small amount of $\mathrm{H}^{+}$is added to the solution.
b. a small amount of $\mathrm{HO}^{-}$is added to the solution.

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Problem 36

You are planning to carry out a reaction that produces hydroxide ion. In order for the reaction to take place at a constant $\mathrm{pH}$, it will be buffered at $\mathrm{pH}=4.2$. Would it be better to use a formic acid/ formate buffer or an acetic acid/acetate buffer? (Note: the $\mathrm{p} K_{\mathrm{a}}$ of formic acid $=3.75$ and the $\mathrm{p} K_{\mathrm{a}}$ of acetic acid $=4.76 .$ )

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Problem 37

What products are formed when each of the following reacts with $\mathrm{HO}^{-} ?$
a. $\mathrm{CH}_{3} \mathrm{OH}$
b. ${ }^{+} \mathrm{NH}_{4}$
c. $\mathrm{CH}_{3} \mathrm{NH}_{3}$
d. $\mathrm{CH}_{3} \mathrm{COOH}$

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Problem 38

a. List the following alcohols in order from strongest acid to weakest acid:
$$
\begin{array}{ccc}
\mathrm{CCl}_{3} \mathrm{CH}_{2} \mathrm{OH} & \mathrm{CH}_{2} \mathrm{ClCH}_{2} \mathrm{OH} & \mathrm{CHCl}_{2} \mathrm{CH}_{2} \mathrm{OH} \\
K_{\mathrm{a}}=5.75 \times 10^{-13} & K_{\mathrm{a}}=1.29 \times 10^{-13} & K_{\mathrm{a}}=4.90 \times 10^{-13}
\end{array}
$$
b. Explain the relative acidities.

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Problem 39

Which is a stronger base?
c. $\mathrm{I}^{-}$or $\mathrm{Cl}^{-}$
e. $\mathrm{CF}_{3} \mathrm{NH}_{2}$ or $\mathrm{CBr}_{3} \mathrm{NH}_{2}$
d. $\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{COO}^{-}$or $\mathrm{CHCl}_{2} \mathrm{COO}^{-}$
f. $\mathrm{CH}_{3}^{-}$or $\mathrm{CH}_{2} \mathrm{CH}^{-}$

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Problem 40

Draw curved arrows to show where the electrons start from and where they end up in the following reactions:

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Problem 41

a. List the following carboxylic acids in order from strongest acid to weakest acid:
$$
\begin{array}{cccc}
\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{CH}_{2} \mathrm{COOH} & \mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{CHCOOH} & \mathrm{ClCH}_{2} \mathrm{CH}_{2} \mathrm{CH}_{2} \mathrm{COOH} & \mathrm{CH}_{3} \mathrm{CHCH}_{2} \mathrm{COOH} \\
K_{\mathrm{a}}=1.52 \times 10^{-5} & \mathrm{Cl} & K_{\mathrm{a}}=2.96 \times 10^{-5} & \mathrm{Cl} \\
& K_{\mathrm{a}}=1.39 \times 10^{-3} & & K_{\mathrm{a}}=8.9 \times 10^{-5}
\end{array}
$$
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 the carboxylic acid?

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Problem 42

For the following compound,
a. draw its conjugate acid.
b. draw its conjugate base.
$\mathrm{H}_{2} \mathrm{NCH}_{2} \mathrm{COOH}$

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Problem 43

List the following compounds in order from strongest acid to weakest acid:
$$
\begin{array}{llll}
\mathrm{CH}_{4} & \mathrm{CH}_{3} \mathrm{COOH} & \mathrm{CH}_{3} \mathrm{OH} & \mathrm{CHCl}_{2} \mathrm{OH}
\end{array}
$$

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Problem 44

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. $\mathrm{CH}_{3} \mathrm{COOH}$
b. $\mathrm{CH}_{3} \mathrm{CH}_{2}+{\mathrm{NH}}_{3}$
c. $\mathrm{CF}_{3} \mathrm{CH}_{2} \mathrm{OH}$

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Problem 45

Give the products of the following acid-base reactions, and indicate whether reactants or products are favored at equilibrium (use the $\mathrm{p} K_{\mathrm{a}}$ values that are given in Section 2.3):
a.
c. $\mathrm{CH}_{3} \mathrm{COH}+\mathrm{CH}_{3} \mathrm{NH}_{2} \rightleftharpoons$
b. $\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{OH}+{ }^{-} \mathrm{NH}_{2} \rightleftharpoons$
d. $\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{OH}+\mathrm{HCl} \rightleftharpoons$

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Problem 46

a. List the following alcohols in order from strongest acid to weakest acid.
b. Explain the relative acidities.
$$
\mathrm{CH}_{2}=\mathrm{CHCH}_{2} \mathrm{OH} \quad \mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{CH}_{2} \mathrm{OH} \quad \mathrm{HC} \equiv \mathrm{CCH}_{2} \mathrm{OH}
$$

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Problem 47

For each compound, indicate the atom that is most likely to be protonated.

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Problem 48

Tenormin, a member of the group of drugs known as beta-blockers, is used to treat high blood pressure and improve survival after a heart attack. It works by slowing down the heart in order to reduce its workload. Which hydrogen in Tenormin is the most acidic?

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Problem 49

From which acids can $\mathrm{HO}^{-}$remove a proton in a reaction that favors product formation?
$$
\begin{array}{cccc}
\mathrm{CH}_{3} \mathrm{COOH} & \mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{NH}_{2} & \mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{NH}_{3} & \mathrm{CH}_{3} \mathrm{C} \equiv \mathrm{CH} \\
\text { A } & \text { B } & \text { C } & \text { D }
\end{array}
$$

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Problem 50

You are planning to carry out a reaction that produces protons. The reaction will be buffered at $\mathrm{pH}=10.5$. Would it be better to use a protonated methylamine/methylamine buffer or a protonated ethylamine/ethylamine buffer? ( $\mathrm{p} K_{\mathrm{a}}$ of protonated methylamine $=10.7$; $\mathrm{p} K_{\mathrm{a}}$ of protonated ethylamine $=11.0$ )

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Problem 51

Which is a stronger acid?
a. $\mathrm{CH}_{3} \mathrm{COOH}$ or $\mathrm{CHCl}_{2} \mathrm{COOH}$
c. $\mathrm{CH}_{3} \mathrm{COOH}$ or $\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{CH}_{2} \mathrm{CH}_{2} \mathrm{CH}_{2} \mathrm{COOH}$

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Problem 52

Citrus fruits are rich in citric acid, a compound with three $\mathrm{COOH}$ groups. Explain why the $\mathrm{p} K_{\mathrm{a}}$ (for the $\mathrm{COOH}$ group in the center of the molecule) is lower than the $\mathrm{p} K_{\mathrm{a}}$ of acetic acid (4.76).

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Problem 53

Carbonic acid has a $\mathrm{p} K_{\mathrm{a}}$ of $6.1$ at physiological temperature. Is the carbonic acid/bicarbonate buffer system that maintains the pH of the blood at $7.4$ better at neutralizing excess acid or excess base?

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Problem 54

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 $1.0 \mathrm{M} \mathrm{NaOH}$. (Hint: See Problem 34.)

Shazia Naz

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