Q: A solution has a $pH$ of 3. What is the $[H^+]$ concentration?

$[H^+] = 1 \times 10^{-3} \text{ M}$

Q: Which of the following is the correct expression for the ion product of water ($K_w$) at $25^A0C$?

$K_w = [H^+][OH^-] = 1.0 \times 10^{-14}$

Question 1

Which of the following best defines chemical equilibrium in a reversible reaction?

Accepted Answer

The forward and reverse reaction rates are equal, resulting in constant concentrations of reactants and products.

Question 2

Given the reaction $aA + bB \rightleftharpoons cC + dD$, which of the following is the correct expression for the equilibrium constant $K_c$?

Accepted Answer

$K_c = \frac{[C]^c [D]^d}{[A]^a [B]^b}$

Question 3

If the equilibrium constant $K$ for a reaction is multiplied by 2, what happens to the value of $K$?

Accepted Answer

The value of $K$ is squared.

Question 4

Consider the reaction $N_2(g) + 3H_2(g) \rightleftharpoons 2NH_3(g)$ at equilibrium. If the concentration of $NH_3$ is increased, what will happen according to Le Chatelier's Principle?

Accepted Answer

The system will shift to the left, producing more $N_2$ and $H_2$.

Question 5

Which of the following statements about acids and bases is correct according to the Bronsted-Lowry definition?

Accepted Answer

A base is a substance that accepts a proton ($H^+$).

Question 6

Which of the following is the correct relationship between $pH$ and $[H^+]$?

Accepted Answer

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

Question 7

A solution has a $pH$ of 3. What is the $[H^+]$ concentration?

Accepted Answer

$[H^+] = 1 	imes 10^{-3} 	ext{ M}$

Question 8

Which of the following will increase the value of the equilibrium constant $K$ for an endothermic reaction?

Accepted Answer

Increasing the temperature.

Question 9

Which of the following is a conjugate acid-base pair?

Accepted Answer

$NH_3$ and $NH_4^+$

Question 10

A buffer solution is prepared by mixing $0.1$ mol of $CH_3COOH$ and $0.1$ mol of $CH_3COONa$ in $1$ L of water. Which equation can be used to calculate the $pH$ of the buffer?

Accepted Answer

$pH = pK_a + \log_{10} \left( \frac{[CH_3COONa]}{[CH_3COOH]} \right)$

Question 11

Which of the following is true about strong acids?

Accepted Answer

They ionize completely in water.

Question 12

If $K_a$ for acetic acid is $1.8 	imes 10^{-5}$, what is the $pK_a$?

Accepted Answer

$pK_a = 4.74$

Question 13

Which of the following is the correct expression for the ion product of water ($K_w$) at $25^ A0C$?

Accepted Answer

$K_w = [H^+][OH^-] = 1.0 	imes 10^{-14}$

Question 14

A $0.01$ M solution of $HCl$ is prepared. What is the $pH$ of the solution?

Accepted Answer

$pH = 2$

Question 15

Which of the following will NOT affect the position of equilibrium in a chemical reaction?

Accepted Answer

Adding a catalyst.

Question 16

A weak acid, $HA$, has a $K_a$ of $1.0 	imes 10^{-6}$. Which of the following statements is true?

Accepted Answer

The acid ionizes only partially in water.

Question 17

Which of the following is the correct $pH$ for a neutral solution at $25^ A0C$?

Accepted Answer

$pH = 7$

Question 18

Which of the following is the correct $pOH$ for a solution with $[OH^-] = 1 	imes 10^{-4}$ M?

Accepted Answer

$pOH = 4$

Question 19

A buffer is made by mixing $0.2$ mol $NH_3$ and $0.1$ mol $NH_4Cl$ in $1$ L of water. If $K_b$ for $NH_3$ is $1.8 	imes 10^{-5}$, what is the $pOH$ of the buffer?

Accepted Answer

$pOH = pK_b + \log_{10} \left( \frac{[NH_4^+]}{[NH_3]} \right)$

Question 20

Which of the following is the correct relationship between $pH$ and $pOH$ in aqueous solution at $25^ A0C$?

Accepted Answer

$pH + pOH = 14$

General Chemistry Study Guide: Chemical Equilibrium, Acids and Bases, and Thermodynamics

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