Question 1

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

Accepted Answer

A substance that donates a proton ($\mathrm{H^+}$) to another substance.

Question 2

What is the pH of a $0.001$ M solution of $\mathrm{HCl}$ (a strong acid) at $25^\circ$C?

Accepted Answer

$3$

Question 3

Which of the following statements is TRUE regarding the relationship between $K_a$ and acid strength?

Accepted Answer

A larger $K_a$ value indicates a stronger acid.

Question 4

A buffer solution is prepared by mixing $0.20$ mol of acetic acid ($\mathrm{CH_3COOH}$) and $0.20$ mol of sodium acetate ($\mathrm{CH_3COONa}$) in $1.0$ L of water. If the $K_a$ of acetic acid is $1.8 	imes 10^{-5}$, what is the pH of the buffer? ($\log 1.8 \approx 0.26$)

Accepted Answer

$4.74$

Question 5

Which of the following best explains why the pH of a buffer solution changes only slightly when a small amount of strong acid is added?

Accepted Answer

The weak base component of the buffer neutralizes the added acid.

Question 6

Which of the following is the correct expression for the $K_b$ of ammonia ($\mathrm{NH_3}$) in water?

Accepted Answer

$K_b = \frac{[\mathrm{NH_4^+}][\mathrm{OH^-}]}{[\mathrm{NH_3}]}$

Question 7

A $0.10$ M solution of a weak acid has a pH of $3.0$. What is the $[\mathrm{H^+}]$ in this solution?

Accepted Answer

$1.0 	imes 10^{-3}$ M

Question 8

Which of the following pairs would NOT form a buffer solution when mixed in equal concentrations?

Accepted Answer

$\mathrm{HCl}$ and $\mathrm{NaCl}$

Question 9

If the $K_a$ of a weak acid is $1.0 	imes 10^{-5}$, what is the $pK_a$?

Accepted Answer

$5.0$

Question 10

A $0.10$ M solution of a weak base has a pOH of $3.0$. What is the $[\mathrm{OH^-}]$ in this solution?

Accepted Answer

$1.0 	imes 10^{-3}$ M

Question 11

During the titration of a weak acid with a strong base, which of the following best describes the pH at the equivalence point?

Accepted Answer

The pH is greater than $7$ because the conjugate base of the weak acid hydrolyzes to produce $\mathrm{OH^-}$.

Question 12

Which of the following is the correct relationship between $K_a$, $K_b$, and $K_w$ for a conjugate acid-base pair?

Accepted Answer

$K_a 	imes K_b = K_w$

Question 13

A $0.10$ M solution of a weak acid is $2\%$ ionized. What is the $[\mathrm{H^+}]$ in the solution?

Accepted Answer

$2.0 	imes 10^{-3}$ M

Question 14

Which of the following best explains why a strong acid has a lower pH than a weak acid of the same concentration?

Accepted Answer

A strong acid ionizes completely, producing a higher $[\mathrm{H^+}]$.

Question 15

Which of the following is the correct order of acid strength (from strongest to weakest) for the following acids: $\mathrm{HCl}$, $\mathrm{CH_3COOH}$, $\mathrm{H_2CO_3}$?

Accepted Answer

$\mathrm{HCl} > \mathrm{CH_3COOH} > \mathrm{H_2CO_3}$

Question 16

A buffer is made by mixing $0.50$ mol of $\mathrm{NH_3}$ and $0.25$ mol of $\mathrm{NH_4Cl}$ in $1.0$ L of solution. If $K_b$ for $\mathrm{NH_3}$ is $1.8 	imes 10^{-5}$, what is the pH of the buffer? ($K_w = 1.0 	imes 10^{-14}$, $\log 1.8 \approx 0.26$)

Accepted Answer

$9.43$

Question 17

Which of the following best describes the effect of dilution on the pH of a buffer solution?

Accepted Answer

The pH remains nearly constant because the ratio of acid to base does not change.

Question 18

During the titration of a strong acid with a strong base, what is the pH at the equivalence point?

Accepted Answer

$7$

Question 19

Which of the following is the correct formula for calculating the pH of a solution given $[\mathrm{H^+}]$?

Accepted Answer

$\mathrm{pH} = -\log [\mathrm{H^+}]$

Question 20

A solution has a pOH of $5.0$. What is the pH of the solution at $25^\circ$C?

Accepted Answer

$9.0$

Acid-Base Equilibria and Additional Aspects of Aqueous Equilibria: Study Notes

Study Guide - Practice Questions

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