Q: Which statement about the autoionization of water is correct?

The product $[H^+][OH^-]$ is always $1.0 \times 10^{-14}$ at 25°C.

Question 1

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

Accepted Answer

A substance that donates a proton ($H^+$) in a chemical reaction.

Question 2

Which of the following pairs are conjugate acid-base pairs?

Accepted Answer

$NH_3$ and $NH_4^+$

Question 3

Given the reaction: $NH_3 + H_2O \rightarrow NH_4^+ + OH^-$, which species acts as the Brønsted-Lowry base?

Accepted Answer

$NH_3$

Question 4

What is the $pH$ of a solution with $[H^+] = 1.0 	imes 10^{-4}$ M?

Accepted Answer

$pH = 4.0$

Question 5

If the $pOH$ of a solution is 3.0 at 25°C, what is the $pH$?

Accepted Answer

$pH = 11.0$

Question 6

Which of the following is a strong acid?

Accepted Answer

$HNO_3$

Question 7

Calculate the $pH$ of a 0.01 M $HCl$ solution.

Accepted Answer

$pH = 2.0$

Question 8

Which statement about the autoionization of water is correct?

Accepted Answer

The product $[H^+][OH^-]$ is always $1.0 	imes 10^{-14}$ at 25°C.

Question 9

A solution has $[OH^-] = 1.0 	imes 10^{-9}$ M. What is its $pH$?

Accepted Answer

$pH = 5.0$

Question 10

Which of the following is true for a weak acid in water?

Accepted Answer

It partially dissociates, and $K_a$ is much less than 1.

Question 11

What is the conjugate base of $HCO_3^-$?

Accepted Answer

$CO_3^{2-}$

Question 12

Which indicator would be most suitable for measuring the $pH$ of a solution expected to be around $pH = 4.5$?

Accepted Answer

Methyl red

Question 13

A student mixes $0.1$ M $NaOH$ with water. What is the $pH$ of the resulting solution?

Accepted Answer

$pH = 13.0$

Question 14

Which of the following equations correctly relates $pH$ and $[H^+]$?

Accepted Answer

$pH = -\log_{10}[H^+]$

Question 15

If $[H^+] = [OH^-]$, what is the $pH$ of the solution at 25°C?

Accepted Answer

$pH = 7.0$

Question 16

Which of the following is a correct statement about strong bases?

Accepted Answer

Strong bases dissociate completely in water to produce $OH^-$ ions.

Question 17

A solution has $pH = 8.5$. Which of the following best describes the solution?

Accepted Answer

It is basic.

Question 18

Which of the following is the acid dissociation constant ($K_a$) expression for $HA \rightleftharpoons H^+ + A^-$?

Accepted Answer

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

Question 19

A weak acid has $K_a = 1.8 	imes 10^{-5}$. If the initial concentration is $0.10$ M, which of the following best describes the $[H^+]$ at equilibrium?

Accepted Answer

Much less than $0.10$ M

Acid-Base Equilibria: Concepts, Calculations, and Applications

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