Question 1

Complete the reaction and draw the curved-arrow notation.

Accepted Answer

The answer of Complete the reaction and draw the curved-arrow...

Question 2

Show the curved-arrow notation and the product (including all unshared valence electrons and formal charges, if any) for the Lewis acid-base association reaction of the two species. (Aluminum is in group 3A of the periodic table, beneath boron.) Then identify and label the nucleophile in the reaction.

Accepted Answer

The answer of Show the curved-arrow notation and the product...

Question 3

Give the products of the electron-pair displacement reaction. (Don't forget unshared pairs and formal charges.) Then circle the nucleophile.

Accepted Answer

The product of the transformation is:
  The hydroxide is the nucleophile.

Question 4

Draw curved arrows and give the products for an electron-pair displacement reaction in which hydroxide ion is the nucleophile and a carbon is the electrophile. Be sure to show all unshared electrons!

Accepted Answer

The answer of Draw curved arrows and give the products...

Question 5

Consider this Brønsted acid-base equilibrium: 1. Fill in the structure of X; show formal charge and all valence electrons. 2. What is K_eq for this reaction for the left-to-right direction? 3. If the reaction starts out with 1 M NaOH and 0.5 M NH₃ in the solvent water (55.5 M), which species (other than water) is present in the highest concentration at equilibrium?

Accepted Answer

The answer of Consider this Brønsted acid-base equilibrium:
  1....

Question 6

Using curved arrows, show how each resonance structure is converted into the other.

Accepted Answer

The answer of Using curved arrows, show how each resonance...

Question 7

Consider the Brønsted acid-base reaction:
  ​
The equilibrium constant for this reaction is 250 (favorable to the right). What is the pKa of HCN (the acid on the right)?

Accepted Answer

The answer of Consider the Brønsted acid-base reaction:
  ​
The...

Question 8

Determine the standard free-energy change of a reaction with an equilibrium constant of 250, given that 2.3RT at 298 K is 5.7 kJ mol^-¹. ΔG° = ________________ kJ mol^-¹.

Accepted Answer

The answer of Determine the standard free-energy change of a...

Question 9

Complete the electron-pair displacement reaction by showing the curved arrows and the structure(s) of the product(s), including all charges and unshared valence electron pairs. Assume that phosphorus is the nucleophilic atom.

Accepted Answer

The answer of Complete the electron-pair displacement reaction by showing...

Question 10

Aspirin has the structure on the left with a pK_a of 3.4. a. Complete the structure on the right for the conjugate base of aspirin. b. In a large excess of stomach acid at pH = 2, calculate the fraction of aspirin that is ionized (to 2 significant figures).

Accepted Answer

The answer of Aspirin has the structure on the left...

Question 11

In this acid-base equilibrium, the pK_a values of the two acids are 4.8 and 9.8, but you must decide which is which from your knowledge of approximate pK_a values. What is the equilibrium constant for this reaction?

Accepted Answer

The answer of In this acid-base equilibrium, the pK_a values...

Question 12

In the reaction, CH₃O⁻ acts as a nucleophile, the phosphorus as an electrophilic center, and CH₃S as a leaving group. (Don't be concerned that phosphorus has more than an octet of electrons-that's allowed, and it's irrelevant to the problem.) a. In the equation, draw the curved arrows for the process described. b. In the box, draw the products of the reaction. Don't forget formal charges.

Accepted Answer

The answer of In the reaction, CH₃O⁻ acts as a...

Question 13

Consider the acid-base equilibrium: a. What is the equilibrium constant K_eq for this reaction? b. In the above equation, circle the strongest base. c. On the left side of the equation, draw the curved arrows that show the formation of the products on the right.

Accepted Answer

The answer of Consider the acid-base equilibrium:
  a. What...

Question 14

The dissociation reaction for an acid has an associated standard free energy change (ΔG°_a) = 28.6 kJ mol⁻¹. What is the pK_a of the acid? (2.3RT at 298 K = 5.71 kJ mol⁻¹.)

Accepted Answer

The answer of The dissociation reaction for an acid has...

Question 15

Select the strongest acid.

Accepted Answer

The answer of Select the strongest acid.

...

Question 16

Select the correct statement about this reaction:
$$\begin{array} { l } 
\mathrm { CH } _ { 3 } \mathrm { CH } _ { 2 } \mathrm { SH } + { } ^ { - } \mathrm { CN }  \rightleftarrows \mathrm { CH } _ { 3 } \mathrm { CH } _ { 2 } \mathrm {~S} ^ { - } + \mathrm { HCN } \
\mathrm { p } K _ { \mathrm { a } } = 10.5 \
p K _ { \mathrm { a } } = 9.4 \
\end{array}$$

Accepted Answer

The equilibrium constant (K) for the reaction can be calculated using the difference in pKa values of the acid (HCN, pKa = 9.4) and the thiol (CH3CH2SH, pKa = 10.5). The difference in pKa values is -1.1 (9.4 - 10.5), which means the equilibrium constant K = 10^(-1.1) ≈ 0.08, indicating the equilibrium lies to the left, favoring reactants.

Question 17

Equal amount of compounds A and B (0.01 mol each) are dissolved together in 1 L of water, and this equilibrium is established:
 What are the major species in solution at equilibrium? (Select all that apply)

Accepted Answer

The answer of Equal amount of compounds A and B...

Question 18

Pivalic acid, which has the structure (CH₃)₃C-CO₂H, has a pK_a of 5.2. The standard free energy of ionization of pivalic acid is ________________ kJ mol⁻¹.

Accepted Answer

The answer of Pivalic acid, which has the structure (CH₃)₃C-CO₂H,...

Question 19

Pentothal is a barbiturate used (as its sodium salt) as a short-acting anesthetic. Pentothal is a weak acid with a dissociation constant K_a = 4 × 10⁻⁸ M. Which one of the statements best describes the dissociation state of pentothal in the blood, which has a pH of 7.4?

Accepted Answer

The answer of Pentothal is a barbiturate used (as its...

Question 20

Choose the number that is closest to the equilibrium constant K_eq for this reaction:

Accepted Answer

The answer of Choose the number that is closest to...

Quiz 3: The Curved-Arrow Notation, Resonance, Acids and Bases, and Chemical Equilibrium

Complete the reaction and draw the curved-arrow notation.

Give the products of the electron-pair displacement reaction. (Don't forget unshared pairs and formal charges.) Then circle the nucleophile.

Draw curved arrows and give the products for an electron-pair displacement reaction in which hydroxide ion is the nucleophile and a carbon is the electrophile. Be sure to show all unshared electrons!

Using curved arrows, show how each resonance structure is converted into the other.

Consider the Brønsted acid-base reaction: The equilibrium constant for this reaction is 250 (favorable to the right). What is the pKa of HCN (the acid on the right)?

Determine the standard free-energy change of a reaction with an equilibrium constant of 250, given that 2.3RT at 298 K is 5.7 kJ mol^-¹. ΔG° = ________________ kJ mol^-¹.

Complete the electron-pair displacement reaction by showing the curved arrows and the structure(s) of the product(s), including all charges and unshared valence electron pairs. Assume that phosphorus is the nucleophilic atom.

Consider the acid-base equilibrium: a. What is the equilibrium constant K_eq for this reaction? b. In the above equation, circle the strongest base. c. On the left side of the equation, draw the curved arrows that show the formation of the products on the right.

The dissociation reaction for an acid has an associated standard free energy change (ΔG°_a) = 28.6 kJ mol⁻¹. What is the pK_a of the acid? (2.3RT at 298 K = 5.71 kJ mol⁻¹.)

Select the strongest acid.

Equal amount of compounds A and B (0.01 mol each) are dissolved together in 1 L of water, and this equilibrium is established: What are the major species in solution at equilibrium? (Select all that apply)

Pivalic acid, which has the structure (CH₃)₃C-CO₂H, has a pK_a of 5.2. The standard free energy of ionization of pivalic acid is ________________ kJ mol⁻¹.

Pentothal is a barbiturate used (as its sodium salt) as a short-acting anesthetic. Pentothal is a weak acid with a dissociation constant K_a = 4 × 10⁻⁸ M. Which one of the statements best describes the dissociation state of pentothal in the blood, which has a pH of 7.4?

Choose the number that is closest to the equilibrium constant K_eq for this reaction:

Quiz 3: The Curved-Arrow Notation, Resonance, Acids and Bases, and Chemical Equilibrium

Complete the reaction and draw the curved-arrow notation.

Give the products of the electron-pair displacement reaction. (Don't forget unshared pairs and formal charges.) Then circle the nucleophile.

Draw curved arrows and give the products for an electron-pair displacement reaction in which hydroxide ion is the nucleophile and a carbon is the electrophile. Be sure to show all unshared electrons!

Using curved arrows, show how each resonance structure is converted into the other.

Consider the Brønsted acid-base reaction: ​ The equilibrium constant for this reaction is 250 (favorable to the right). What is the pKa of HCN (the acid on the right)?

Determine the standard free-energy change of a reaction with an equilibrium constant of 250, given that 2.3RT at 298 K is 5.7 kJ mol-1. ΔG° = ________________ kJ mol-1.

Complete the electron-pair displacement reaction by showing the curved arrows and the structure(s) of the product(s), including all charges and unshared valence electron pairs. Assume that phosphorus is the nucleophilic atom.

Aspirin has the structure on the left with a pKa of 3.4. ​a. Complete the structure on the right for the conjugate base of aspirin. b. In a large excess of stomach acid at pH = 2, calculate the fraction of aspirin that is ionized (to 2 significant figures).

In this acid-base equilibrium, the pKa values of the two acids are 4.8 and 9.8, but you must decide which is which from your knowledge of approximate pKa values. What is the equilibrium constant for this reaction?

Consider the acid-base equilibrium: a. What is the equilibrium constant Keq for this reaction? b. In the above equation, circle the strongest base. c. On the left side of the equation, draw the curved arrows that show the formation of the products on the right.

The dissociation reaction for an acid has an associated standard free energy change (ΔG°a) = 28.6 kJ mol−1. What is the pKa of the acid? (2.3RT at 298 K = 5.71 kJ mol−1.)

Select the strongest acid.

Equal amount of compounds A and B (0.01 mol each) are dissolved together in 1 L of water, and this equilibrium is established: What are the major species in solution at equilibrium? (Select all that apply)

Pivalic acid, which has the structure (CH3)3C-CO2H, has a pKa of 5.2. The standard free energy of ionization of pivalic acid is ________________ kJ mol−1.

Pentothal is a barbiturate used (as its sodium salt) as a short-acting anesthetic. Pentothal is a weak acid with a dissociation constant Ka = 4 × 10−8 M. Which one of the statements best describes the dissociation state of pentothal in the blood, which has a pH of 7.4?

Choose the number that is closest to the equilibrium constant Keq for this reaction:

Consider the Brønsted acid-base reaction: The equilibrium constant for this reaction is 250 (favorable to the right). What is the pKa of HCN (the acid on the right)?

Determine the standard free-energy change of a reaction with an equilibrium constant of 250, given that 2.3RT at 298 K is 5.7 kJ mol^-¹. ΔG° = ________________ kJ mol^-¹.

Consider the acid-base equilibrium: a. What is the equilibrium constant K_eq for this reaction? b. In the above equation, circle the strongest base. c. On the left side of the equation, draw the curved arrows that show the formation of the products on the right.

The dissociation reaction for an acid has an associated standard free energy change (ΔG°_a) = 28.6 kJ mol⁻¹. What is the pK_a of the acid? (2.3RT at 298 K = 5.71 kJ mol⁻¹.)

Pivalic acid, which has the structure (CH₃)₃C-CO₂H, has a pK_a of 5.2. The standard free energy of ionization of pivalic acid is ________________ kJ mol⁻¹.

Pentothal is a barbiturate used (as its sodium salt) as a short-acting anesthetic. Pentothal is a weak acid with a dissociation constant K_a = 4 × 10⁻⁸ M. Which one of the statements best describes the dissociation state of pentothal in the blood, which has a pH of 7.4?

Choose the number that is closest to the equilibrium constant K_eq for this reaction: