$$1.5 \times 10$$^{-2}$$ \ \mathrm{M}$$

$$3.3 \times 10$$^{-11}$$ \ \mathrm{M}$$

$$[H_3O^+] = 1.0 \times 10$$^{-3.523}$$ \ \mathrm{M}$$

Question 1

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

Accepted Answer

A substance that donates a proton

Question 2

A 1.5 	imes $$10^{-2}$$ \ \mathrm{M} solution of $$HNO_3 is $$prepared. What is the [H_3O^+] in this solution?

Accepted Answer

$$1.5 	imes 10$$^{-2}$$ \ \mathrm{M}$$

Question 3

Which of the following statements is true about strong acids in water?

Accepted Answer

They dissociate completely, so [HA] approaches zero.

Question 4

Given $$K_a$$ values for several acids, which acid is the weakest?

Accepted Answer

The acid with the smallest $$K_a$$ value

Question 5

A solution of 0.50 M HF at 25°C has $$K_a = 7.2 	imes 10$$^{-4}$$. Which expression correctly represents the K_a$ for this acid?

Accepted Answer

$$K_a = \frac{[H_3O^+][F^-]}{[HF]}$$

Question 6

A chemist adds HCl gas to pure water at 25°C and measures $$[H_3O^+] = 3.0 	imes 10$$^{-4}$$ \ \mathrm{M}. $$What is $$[OH^-] in $$the solution?

Accepted Answer

$$3.3 	imes 10$$^{-11}$$ \ \mathrm{M}$$

Question 7

Which of the following best describes a Lewis base?

Accepted Answer

An electron pair donor

Question 8

A 0.85 M solution of $$NH_3 at 25$$°C has $$K_b = 1.8 	imes 10$$^{-5}$$. What is the correct expression for K_b$?

Accepted Answer

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

Question 9

A solution has a pH of 3.523. What is the $$[H_3O^+]$$?

Accepted Answer

$$[H_3O^+] = 1.0 	imes 10$$^{-3.523}$$ \ \mathrm{M}$$

Question 10

Which of the following solutions is most basic?

Accepted Answer

A solution with pH = 13.323

Question 11

A 2.0 M NaOH solution is prepared for cleaning. What is the $$[OH^-] in $$this solution?

Accepted Answer

$$2.0 \ \mathrm{M}$$

Question 12

What is the pH of pure water at 25°C?

Accepted Answer

$$7$$

Question 13

A 0.100 M solution of propanoic acid (HA) has $$K_a = 1.30 	imes 10$$^{-5}$$. Which assumption is valid for simplifying the equilibrium calculation?

Accepted Answer

The change in [HA] is negligible if $$K_a is $$small and initial [HA] is large

Question 14

A solution of 8.00 M formic acid is 0.47% ionized in water. What is the best method to calculate $$K_a$$?

Accepted Answer

Use the percent ionization to find [H_3O^+], then substitute into $$K_a = \frac{[H_3O^+][A^-]}{[HA]}$$

Question 15

Which of the following is a correct statement about the relationship between $$K_a$$ and $$pK_a$$?

Accepted Answer

$$pK_a = -\log K_a$$

Question 16

A solution is prepared by adding 0.050 mol HA ($$K_a = 1.5 	imes 10$$^{-5}$$) and 0.0050 mol A- to 0.500 L of water. What type of problem is this?

Accepted Answer

A common ion problem

Question 17

Which of the following best explains why strong acids do not have $$K_a$$ values?

Accepted Answer

Their $$K_a$$ values are so large they approach infinity, indicating complete dissociation

Question 18

A 1.5 M solution of dimethylamine ($$(CH_3$)_2NH) $$has $$K_b = 5.9 	imes 10$$^{-4}$$. What is the correct setup to find the pH of this solution?

Accepted Answer

Calculate $$[OH^-]$$ using $$K_b$$, then use $$pOH = -\log[OH^-]$$ and $$pH = 14 - pOH$$

Question 19

Which of the following is a real-world application of weak acid equilibrium calculations?

Accepted Answer

Determining the pH of blood in medical diagnostics

Acid-Base Equilibria: Properties, Strength, and Calculations in Aqueous Solution

Study Guide - Practice Questions