Free Practice Quiz Question List

03 Acids, Bases, and Curved-Arrow Notation Online Quiz Questions

Use this free practice quiz with 20 questions to review 03 Acids, Bases, and Curved-Arrow Notation, test your knowledge, and prepare for your next test or exam.

20 questions

True or false

1 point

True or false: You can always rank two acids by comparing their pKa values directly, even when the values were measured in different solvents.

A
True
B
False

Written response

1 point

In the proton-transfer reaction $\mathrm{OH^- + H^+ \rightarrow H_2O}$ , what is the conjugate acid of hydroxide?

Choose one

1 point

In $\mathrm{CH_3CO_2H + OH^- \rightleftharpoons CH_3CO_2^- + H_2O}$ , which product is the conjugate base formed from acetic acid?

A
Hydroxide
B
Acetate
C
Water
D
Acetic acid

Choose one

1 point

In $\mathrm{NH_3 + BF_3 \rightarrow H_3N{-}BF_3}$ , which description correctly identifies the electron-pair roles?

A
$\mathrm{NH_3}$ is the Lewis acid, and $\mathrm{BF_3}$ is the Lewis base.
B
$\mathrm{NH_3}$ is the Lewis base, and $\mathrm{BF_3}$ is the Lewis acid.
C
Both $\mathrm{NH_3}$ and $\mathrm{BF_3}$ are Lewis acids.
D
Neither reactant participates as a Lewis acid or base.

True or false

1 point

True or false: A reaction can be a Lewis acid–base reaction even if no proton is transferred, as long as one species donates an electron pair and another accepts it.

A
True
B
False

Choose one

1 point

Which pair of curved arrows correctly represents proton transfer from acetic acid to hydroxide?

A
Move an arrow from the acidic hydrogen to hydroxide, then from oxygen to the O–H bond.
B
Move an arrow from the acetic acid oxygen to hydroxide, then from the hydrogen to oxygen.
C
Move an arrow from a hydroxide oxygen lone pair to the acidic hydrogen, and another from the acetic acid O–H bond to its oxygen.
D
Move both arrows from the acidic hydrogen, one to hydroxide and one to oxygen.

Written response

1 point

Acid X has $\mathrm{p}K_a = 2$ and acid Y has $\mathrm{p}K_a = 5$ . By what factor is $K_a$ for X greater than $K_a$ for Y?

Choose all

1 point

Select all statements that correctly describe curved-arrow notation.

A
The tail of a curved arrow begins at the electrons being moved.
B
The head of a curved arrow points to where those electrons go.
C
A curved arrow shows the movement of an atom by itself, independently of its electrons.
D
A full-headed arrow represents two electrons, whereas a fishhook arrow represents one electron.

Choose all

1 point

For HA + B⁻ ⇌ A⁻ + HB, pKa(HA) is 4.0 and pKa(HB) is 4.2. Select all conclusions supported by these values.

A
Products are favored because HB has the higher pKa.
B
Reactants are favored because HA has the lower pKa.
C
Neither side is overwhelmingly favored because the pKa values are similar.
D
The reaction must go completely to products.

Choose one

1 point

Which expression gives the logarithmic definition of $\mathrm{p}K_a$ ?

A
$\mathrm{p}K_a = \log_{10} K_a$
B
$\mathrm{p}K_a = -\log_{10} K_a$
C
$\mathrm{p}K_a = 10K_a$
D
$\mathrm{p}K_a = K_a - 10$

Choose one

1 point

Acid X has a lower pKa than acid Y, with both values measured under comparable conditions. Which statement correctly compares their conjugate bases?

A
The conjugate base of acid X is stronger.
B
The conjugate bases are equally strong.
C
The conjugate base of acid X is weaker.
D
The pKa values alone say nothing about relative conjugate-base strength.

Open ended

1 point

For the general proton-transfer equilibrium $\mathrm{HA + B^- \rightleftharpoons A^- + HB}$ , explain how to use the two acid pKa values to estimate which side is favored. Include the approximate relationship for $K$ and describe what happens when the pKa values are similar.

Choose one

1 point

In the reaction $\mathrm{CH_3CO_2H + OH^- \rightleftharpoons CH_3CO_2^- + H_2O}$ , what is the conjugate base of acetic acid?

A
Water, because it receives a proton
B
Acetate, because acetic acid loses a proton
C
Hydroxide, because it donates a proton
D
Acetic acid, because it accepts a proton

True or false

1 point

A full-headed curved arrow represents the movement of two electrons, whereas a fishhook arrow represents one electron.

A
True
B
False

Choose one

1 point

In the Lewis acid–base reaction $\mathrm{NH_3 + BF_3 \rightarrow H_3N{-}BF_3}$ , which description explains the bond formation?

A
BF₃ donates a proton to ammonia, forming an N–H bond.
B
Ammonia accepts an electron pair from BF₃, forming a B–H bond.
C
Ammonia donates a lone pair to boron, forming an N–B bond.
D
Ammonia donates a proton to BF₃, forming a B–N bond.

Written response

1 point

Using $\mathrm{p}K_\mathrm{a}(\text{acetic acid}) \approx 4.8$ and $\mathrm{p}K_\mathrm{a}(\text{water}) \approx 15.7$ , what is the difference $\mathrm{p}K_\mathrm{a}(\text{water}) - \mathrm{p}K_\mathrm{a}(\text{acetic acid})$ , to one decimal place?

Choose one

1 point

For $\mathrm{CH_3CO_2H + OH^- \rightleftharpoons CH_3CO_2^- + H_2O}$ , which pair of curved-arrow directions correctly depicts proton transfer?

A
From a hydroxide oxygen lone pair to the acidic hydrogen, and from the acid’s O–H bond to its oxygen
B
From the acidic hydrogen to hydroxide, and from the acid’s oxygen to the O–H bond
C
From the acid’s O–H bond to hydroxide, and from a hydroxide lone pair to the acid’s oxygen
D
From hydroxide oxygen to the acid’s oxygen, and from the acidic hydrogen to the O–H bond

Written response

1 point

When hydroxide accepts a proton in a Brønsted acid–base reaction, what is the name of the resulting conjugate acid?

Fill in the blank

1 point

In the reaction $\mathrm{CH_3CO_2H + OH^- \rightleftharpoons CH_3CO_2^- + H_2O}$ , the Brønsted acid is , and the Brønsted base is .

Fill in the blank

1 point

For an acid HA, the acid-dissociation constant Ka describes its tendency to .