Question 1

Which of the following statements about resonance forms is CORRECT?

Accepted Answer

The resonance hybrid is more stable than any individual resonance form.

Question 2

Which of the following is NOT a valid resonance structure for the acetate ion?

Accepted Answer

A structure where a carbon atom has 10 electrons around it.

Question 3

Given the following acid-base reaction: $$\mathrm{CH_3COOH} + \mathrm{OH^-} \rightarrow \mathrm{CH_3COO^-} + \mathrm{H_2O}$$, which direction will the equilibrium favor based on pKa values?

Accepted Answer

Toward the formation of acetate ion and water.

Question 4

Which of the following best describes a Brønsted–Lowry acid?

Accepted Answer

A substance that donates a hydrogen ion ($$\mathrm{H^+}).$$

Question 5

What is the pKa value for water ($$\mathrm{H_2O}$$)?

Accepted Answer

$$15.74$$

Question 6

Which of the following organic compounds is the strongest acid based on the given pKa values?

Accepted Answer

Acetic acid ($$pK_a = 4.76)$$

Question 7

Which of the following is a characteristic of a Lewis base?

Accepted Answer

It donates an electron pair.

Question 8

Which of the following is stabilized by resonance and by having the negative charge on a highly electronegative atom?

Accepted Answer

The acetate ion ($$\mathrm{CH_3COO^-})$$

Question 9

Which of the following is a valid application of the pKa concept in predicting acid-base reactions?

Accepted Answer

A reaction will proceed from the stronger acid to the weaker acid side.

Question 10

Which of the following compounds is an example of a Lewis acid?

Accepted Answer

$$\mathrm{BF_3$} ($$boron trifluoride)

Question 11

Which of the following best explains why carboxylic acids are common in metabolic pathways?

Accepted Answer

They contain the $$-\mathrm{CO_2H}$$ group, which is reactive and can stabilize anions by resonance.

Question 12

Which of the following is a correct statement about the movement of electrons in resonance structures?

Accepted Answer

Curved arrows indicate the movement of electrons.

Question 13

Which of the following is a Brønsted–Lowry base in the reaction $$\mathrm{NH_3$} + \mathrm{H_2O} \rightarrow \mathrm{NH_4$^+} + \mathrm{OH^-}$$?

Accepted Answer

$$\mathrm{NH_3$}$$

Question 14

Which of the following organic molecules can act as a Lewis base due to the presence of a lone pair of electrons?

Accepted Answer

Methanol ($$\mathrm{CH_3OH})$$

Question 15

Which of the following is the correct expression for the acid dissociation constant ($$K_a) $$for a generic acid $$HA in $$water?

Accepted Answer

$$K_a = \frac{[H_3O^+][A^-]}{[HA]}$$

Question 16

Which of the following is a correct statement about the stability of resonance hybrids?

Accepted Answer

The resonance hybrid is more stable than any individual resonance form.

Question 17

Which of the following is a Lewis acid in the reaction between $$\mathrm{BF_3$}$$ and dimethyl ether ($$\mathrm{(CH_3$)_2O}$$)?

Accepted Answer

$$\mathrm{BF_3$}$$

Question 18

Which of the following best explains why the acetate ion is stabilized after deprotonation of acetic acid?

Accepted Answer

The negative charge is delocalized by resonance over two oxygen atoms.

Polar Covalent Bonds; Acids and Bases – Resonance, Acid-Base Theories, and Organic Examples

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