Polar Covalent Bonds: Acids and Bases

Assign formal charges to the atoms in each of the following molecules:

Question: Assign formal charges to the atoms in each of the following molecules:

Question: Assign formal charges to the atoms in each of the following molecules:

Assign formal charges to the atoms in each of the following molecules:

a.

b.

c.

Question: Which of the following pairs of structures represent resonance forms?

Question: Which of the following pairs of structures represent resonance forms?

Question: Which of the following pairs of structures represent resonance forms?

Question: Which of the following pairs of structures represent resonance forms?

Which of the following pairs of structures represent resonance forms?

a.

b.

c.

d.

Question: Draw as many resonance structures as you can for the following species. 

Question: Draw as many resonance structures as you can for the following

species:

Question: Draw as many resonance structures as you can for the following

species:

Draw as many resonance structures as you can for the following species:

a. 

b.

c.

d.

e.

Write the products of the following acid–base reactions:$\begin{array}{l}\left(a\right)C{H}_{3}OH+H_{2}S{O}_4\rightleftarrows ?\\ \left(b\right)C{H}_{3}OH+NaN{H}_2\rightleftarrows ?\\ \left(c\right)C{H}_{3}N{H_3}^{+}+C{l}^{-}+NaOH\rightleftarrows ?\end{array}$

Rank the following substances in order of increasing acidity:

Which, if any, of the substances in Problem 2-44 is a strong enough acidto react almost completely with NaOH? (The $\mathbf{p}{K}_a$ of  is 15.74.)

The ammonium ion ( ${{\mathbf{NH}}_4}^{+}$, pK_a=9.25) has a lower pKa than the

methylammoniumion (${\mathbf{CH}}_3{{\mathbf{NH}}_3}^{+}$ , pK_a=10.66). Which is the stronger

base, ammonia $\left({\mathbf{NH}}_3\right)$ or methylamine $\left({\mathbf{CH}}_3{\mathbf{NH}}_2\right)$ ? Explain.

Is tert-butoxide anion a strong enough base to react significantly with

water? In other words, can a solution of potassium tert-butoxide be

prepared in water? The pK_a of tert-butyl alcohol is approximately 18.

Predict the structure of the product formed in the reaction of the organic base pyridine with the organic acid acetic acid, and use curved arrows to indicate the direction of electron flow.

Calculate  values from the following ’s:

(a) Acetone,  $p{K}_a$=19.3 (b) Formic acid,  $p{K}_a$=3.75

Calculate  values from the following  ’s:

(a) Nitromethane,  $K_a$= $\mathbf{5}\mathbf{.}\mathbf{0}\mathbf{\times }{\mathbf{10}}^{-11}$

(b) Acrylic acid, $K_a$ = $\mathbf{5}\mathbf{.}\mathbf{6}\mathbf{\times }{\mathbf{10}}^{-5}$

What is the pH of a 0.050 M solution of formic acid, $\text{p}{K}_a$= 3.75?

Sodium bicarbonate, NaHCO₃, is the sodium salt of carbonic acid$\left({\mathbf{H}}_2{\mathbf{CO}}_3\right)$

 ,  $p{K}_a$=6.37. Which of the substances shown in Problem 2-44

will react significantly with sodium bicarbonate?

Maleic acid has a dipole moment, but the closely related fumaric acid,

a substance involved in the citric acid cycle by which food molecules

are metabolized, does not. Explain.

Assume that you have two unlabeled bottles, one of which contains

phenol ( $\mathbf{p}{K}_a$9.9) and one of which contains acetic acid ($\mathbf{p}{K}_a$ =4.76).

In light of your answer to Problem 2-52, suggest a simple way to determine

what is in each bottle.

Which of the following pairs represent resonance structures?

Carbocations, which contain a trivalent, positively charged carbon atom, react with water to give alcohols:

How can your account for the fact that the following carbocation gives a mixture of two alcohols in reaction with water?

The azide functional group, which occurs in azido benzene, contains three adjacent nitrogen atoms. One resonance structure for azido benzene is shown. Draw three additional resonance structures, and assign appropriate formal charges to the atoms in all four.

Thiamin diphosphate (TPP), a derivative of vitamin B1 required for glucose metabolism, is a weak acid that can be deprotonated by a base. Assign formal charges to the appropriate atoms in both TPP and its deprotonation product.

Determine if each compound or ion below has a dipole moment.

(a) Carbonate ion  $\left({{\mathbf{CO}}_3}^{2-}\right)$

Determine if each compound or ion below has a dipole moment.

(a) Carbonate ion  $\left({{\mathbf{CO}}_3}^{2-}\right)$

(b)  $\mathbf{-}\underset{\mathrm{..}}{\overset{\mathrm{..}}{O}}\mathbf{-}$

(c) $\stackrel{+}{C}{\left({\mathbf{CH}}_3\right)}_3$

Determine if each compound or ion below has a dipole moment.

(a) Carbonate ion  $\left({{\mathbf{CO}}_3}^{2-}\right)$

(b)  $\mathbf{-}\underset{\mathrm{..}}{\overset{\mathrm{..}}{O}}\mathbf{-}$

(c) $\stackrel{+}{C}{\left({\mathbf{CH}}_3\right)}_3$

Use the pK_a  table in Appendix B to determine in which direction the

Equilibrium is favored.

(a)

Which intermolecular force is predominantly responsible for each

Observation  below?

(a) ${\mathbf{CH}}_3{\left({\mathbf{CH}}_3\right)}_{29}{\mathbf{CH}}_3$, a component found in paraffin wax, is a solid at

Room temperature while octane is a liquid.${\mathbf{CH}}_3{\mathbf{\left(}{\mathbf{CH}}_2\mathbf{\right)}}_4{\mathbf{CH}}_3$

 (b) ${\mathbf{CH}}_3{\mathbf{CH}}_2{\mathbf{CH}}_2\mathbf{OH}$ has a higher boiling point than  ${\mathbf{CH}}_4$

(c) ${\mathbf{CH}}_3{\mathbf{CO}}_2\mathbf{H}$, which is found in vinegar, will dissolve in water but not

In oil—for simplicity you may assume oil is ${\mathbf{CH}}_3{\left({\mathbf{CH}}_2\right)}_4{\mathbf{CH}}_3$ .

1,1,1-Trichloroethanol is an acid more than 1000 times stronger than ethanol, even though both have a conjugate base where the negative charge is on an oxygen. Provide an explanation for this observation.