$K_b = \dfrac{[\text{NH}_4^+][\text{OH}^-]}{[\text{NH}_3]}

$$\text{pH} + \text{pOH} = 14$$

$$\text{pH} = 14 - \log[\text{OH}^-]$$

Question 1

Which of the following best describes a Bronsted-Lowry acid?

Accepted Answer

A substance that donates a proton (H$$^+) to $$another substance.

Question 2

Which of the following is a Lewis base?

Accepted Answer

NH$$_3$$, because it donates a pair of electrons.

Question 3

Which of the following statements about the autoionization of water is correct?

Accepted Answer

It produces equal concentrations of H$$_3O$^+$$ and OH$$^-$$ ions.

Question 4

Given that $$K_w = 1.0 	imes 10$$^{-14}$$ at 25$$^\circ$$C, what is the pH of pure water at this temperature?

Accepted Answer

$$	ext{pH} = 7.00$$

Question 5

Which salt will produce a basic solution when dissolved in water?

Accepted Answer

NaF

Question 6

Which of the following acids is expected to be the strongest based on molecular structure?

Accepted Answer

HClO$$_4$$

Question 7

A 0.10 M solution of acetic acid ($$K_a = 1.8 	imes 10$$^{-5}$$) is prepared. What is the pH of the solution? (Assume x$$ \ll 0.10$$)

Accepted Answer

$$	ext{pH} = 2.87$$

Question 8

Which of the following best explains why HF is a weak acid while HCl is a strong acid?

Accepted Answer

The H–F bond is much stronger than the H–Cl bond, making HF less likely to ionize.

Question 9

Calculate the percent ionization of a 0.20 M solution of a weak acid, HA, with $$K_a = 1.0 	imes 10$$^{-5}$$.

Accepted Answer

0.7\%

Question 10

A solution is prepared by mixing 50.0 mL of 0.10 M HCl and 50.0 mL of 0.10 M HNO$$_3. $$What is the resulting pH?

Accepted Answer

$$	ext{pH} = 1.00$$

Question 11

Which of the following is the correct expression for the base dissociation constant, $$K_b$$, for ammonia ($$	ext{NH}_3) in $$water?

Accepted Answer

$K_b = \dfrac{[	ext{NH}_4^+][	ext{OH}^-]}{[	ext{NH}_3]}

Question 12

If the $$K_a of a $$weak acid is $$1.0 	imes 10$$^{-6}$$, what is the K_b$ of its conjugate base at 25$$^\circ$$C?

Accepted Answer

$$K_b = 1.0 	imes 10$$^{-8}$$

Question 13

Which of the following solutions has the lowest pH?

Accepted Answer

0.10 M HNO$$_3$$

Question 14

Which of the following is NOT a correct conjugate acid-base pair?

Accepted Answer

H$$_2O / OH$^-$$

Question 15

A solution has a pH of 9.25. What is the concentration of H$$_3O$^+ in $$the solution?

Accepted Answer

$$5.6 	imes 10$$^{-10}$$ M

Question 16

Which of the following best explains why the acidity of oxoacids increases with increasing number of oxygen atoms?

Accepted Answer

Additional oxygen atoms stabilize the negative charge on the conjugate base through delocalization.

Question 17

Which of the following is the correct relationship between pH and pOH in aqueous solution at 25$$^\circC$$?

Accepted Answer

$$	ext{pH} + 	ext{pOH} = 14$$

Question 18

A 0.10 M solution of a weak base, B, has a pH of 11.00. What is the $$K_b$$ for this base?

Accepted Answer

$$1.0 	imes 10$$^{-5}$$

Question 19

Which of the following best describes the effect of adding NaCH$$_3$$COO to a solution of acetic acid?

Accepted Answer

The percent ionization of acetic acid decreases due to the common ion effect.

Question 20

Which of the following is the correct formula for calculating the pH of a strong base solution such as 0.010 M NaOH?

Accepted Answer

$$	ext{pH} = 14 - \log[	ext{OH}^-]$$

Acids, Bases, and Aqueous Equilibria: Concepts, Calculations, and Applications

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