$$K_b = 5.6 \times 10$$^{-10}$$

Question 1

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

Accepted Answer

A substance that donates a proton.

Question 2

Which of the following pairs represents a conjugate acid-base pair?

Accepted Answer

NH$$_3$$ and NH$$_4^+$$

Question 3

Which of the following is a strong acid?

Accepted Answer

HNO$$_3$$

Question 4

Which of the following bases is considered weak?

Accepted Answer

NH$$_3$$

Question 5

Given a weak acid with a pKa of 4.75, which acid is stronger?

Accepted Answer

An acid with pKa = 2.0

Question 6

If the Ka for a weak acid is $$1.8 	imes 10$$^{-5}$$, what is the Kb for its conjugate base? (Given K_w = 1.0$$ 	imes $$10^{-14})$$

Accepted Answer

$$K_b = 5.6 	imes 10$$^{-10}$$

Question 7

What is the pH of a solution with $$[H^+] = 2.5 	imes 10$$^{-3}$$ M?

Accepted Answer

pH = 2.60

Question 8

Which of the following statements is true about the relationship between pH and acidity?

Accepted Answer

A lower pH means a more acidic solution.

Question 9

A buffer solution is prepared using acetic acid and sodium acetate. Which equation is used to calculate its pH?

Accepted Answer

$$pH = pK_a + \log \left( \frac{[A^-]}{[HA]} \right)$$

Question 10

Which salt will produce a basic solution in water?

Accepted Answer

NaCH$$_3$$COO

Question 11

What is the percent dissociation of a 0.10 M solution of a weak acid with $$K_a = 1.0 	imes 10$$^{-4}$$?

Accepted Answer

1.0%

Question 12

Which of the following acids is polyprotic?

Accepted Answer

H$$_3PO$_4$$

Question 13

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

Accepted Answer

pH \u003e 7

Question 14

Which structural feature increases the strength of an acid?

Accepted Answer

Presence of electron-withdrawing groups

Question 15

If a buffer solution contains 0.20 M acetic acid and 0.10 M acetate, and $$pK_a = 4.76$$, what is the pH?

Accepted Answer

pH = 4.46

Question 16

Which of the following best explains why a buffer resists changes in pH when small amounts of acid or base are added?

Accepted Answer

The buffer neutralizes added acid or base through Le Chatelier's principle.

Question 17

What is the equilibrium constant expression for the dissociation of a weak acid HA?

Accepted Answer

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

Question 18

Which of the following best describes the effect of adding a common ion to a solution of a weak acid?

Accepted Answer

The acid dissociates less, decreasing [H$$^+$$].

Question 19

Which titration curve would show a sharp increase in pH at the equivalence point?

Accepted Answer

Strong acid titrated with strong base

Question 20

A buffer is made from 0.50 M NH$$_3$$ and 0.50 M NH$$_4^+$$, with $$pK_b = 4.75. $$What is the pOH?

Accepted Answer

pOH = 4.75

Acids, Bases, and Aqueous Ionic Equilibria – Study Guide

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