Question

name:

1. how does an indicator provide information about the ph of a solution?

a. by reacting with acids or bases in solution and forming a colored complex
b. by dissociating into ions that have a different color than the molecular form
c. by reducing the number of free hydronium or hydroxide ions in solution
d. by causing the acid or base in solution to dissociate into a colored form

1. what are the brønsted-lowry acids in the following equilibrium reaction?

\\(\text{cn}^- + \text{h}_2\text{o} \
ightleftharpoons \text{hcn} + \text{oh}^-\\)
a. \\(\text{cn}^-, \text{h}_2\text{o}\\)
b. \\(\text{h}_2\text{o}, \text{hcn}\\)
c. \\(\text{cn}^-, \text{oh}^-\\)
d. \\(\text{h}_2\text{o}, \text{oh}^-\\)

1. which of the following represents a brønsted-lowry conjugate acid-base pair?

a. \\(\text{so}_3^{2-}\\) and \\(\text{so}_2\\)
b. \\(\text{co}_3^{2-}\\) and \\(\text{co}\\)
c. \\(\text{h}_2\text{o}\\) and \\(\text{h}_2\\)
d. \\(\text{nh}_4^+\\) and \\(\text{nh}_3\\)

1. the products of self-ionization of water are _______

a. \\(\text{h}_3\text{o}^+\\) and \\(\text{h}_2\text{o}\\)
b. \\(\text{oh}^-\\) and \\(\text{oh}_2^+\\)
c. \\(\text{oh}^-\\) and \\(\text{h}^-\\)
d. \\(\text{oh}^-\\) and \\(\text{h}_3\text{o}^+\\)

1. in a neutral solution, \\(\text{h}^+\\) is _______

a. \\(10^{-14} m\\)
b. zero
c. \\(1 \times 10^7 m\\)
d. equal to \\(\text{oh}^-\\)

1. which type of solution is one with a ph of 8?

a. acidic
b. basic
c. neutral
d. the type varies, depending on the solution.

1. what characterizes a strong acid or base?

a. polar covalent bonding
b. complete ionization in water
c. ionic bonding
d. presence of a hydroxide or hydrogen ion

Explanation:

Mechanism of Acid-Base Indicators

Using the Acid-Base Indicators knowledge point
An indicator is a weak acid or base whose conjugate forms display different colors due to structural changes upon protonation/deprotonation.

$$ \text{HIn (color A)} ightleftharpoons \text{H}^+ + \text{In}^- \text{ (color B)} $$

Identifying Brønsted-Lowry Acids

Using the Bronsted-Lowry Theory knowledge point
A Brønsted-Lowry acid is a proton (\(\text{H}^+\)) donor.
In the forward reaction:

$$ \text{H}_2\text{O} ightarrow \text{OH}^- \quad (\text{donates } \text{H}^+) $$

In the reverse reaction:

$$ \text{HCN} ightarrow \text{CN}^- \quad (\text{donates } \text{H}^+) $$

Conjugate Acid-Base Pairs

Using the Conjugate Acid-Base Pairs knowledge point
A conjugate acid-base pair consists of two species that differ by exactly one proton (\(\text{H}^+\)).

$$ \text{NH}_4^+ ightleftharpoons \text{NH}_3 + \text{H}^+ $$

Products of Water Self-Ionization

Using the Self-Ionization of Water knowledge point
Water molecules transfer a proton to form hydronium and hydroxide ions.

$$ 2\text{H}_2\text{O} ightleftharpoons \text{H}_3\text{O}^+ + \text{OH}^- $$

Neutral Solution Characteristics

Using the Neutral Solution pH knowledge point
In pure water at \(25^\circ\text{C}\), the concentrations of hydrogen and hydroxide ions are equal.

$$ [\text{H}^+] = [\text{OH}^-] = 1.0 \times 10^{-7}\text{ M} $$

pH Scale Classification

A solution's pH indicates its acidity or basicity:

• \(\text{pH} < 7\): Acidic
• \(\text{pH} = 7\): Neutral
• \(\text{pH} > 7\): Basic

A pH of 8 is greater than 7, which means the solution is basic.

Strength of Acids and Bases

Using the Strong Acids and Bases knowledge point
Strength is defined by the extent of dissociation in aqueous solution.

$$ \text{HA} + \text{H}_2\text{O} ightarrow \text{H}_3\text{O}^+ + \text{A}^- \quad (\approx 100\% \text{ ionization}) $$

Answer:

Question 104

• a. by reacting with acids or bases in solution and forming a colored complex
• b. by dissociating into ions that have a different color than the molecular form (Correct answer)
• c. by reducing the number of free hydronium or hydroxide ions in solution
• d. by causing the acid or base in solution to dissociate into a colored form

Question 105

• a. \(\text{CN}^-\), \(\text{H}_2\text{O}\)
• b. \(\text{H}_2\text{O}\), \(\text{HCN}\) (Correct answer)
• c. \(\text{CN}^-\), \(\text{OH}^-\)
• d. \(\text{H}_2\text{O}\), \(\text{OH}^-\)

Question 106

• a. \(\text{SO}_3^{2-}\) and \(\text{SO}_2\)
• b. \(\text{CO}_3^{2-}\) and \(\text{CO}\)
• c. \(\text{H}_3\text{O}^+\) and \(\text{H}_2\)
• d. \(\text{NH}_4^+\) and \(\text{NH}_3\) (Correct answer)

Question 107

• a. \(\text{H}_2\text{O}^+\) and \(\text{H}_2\text{O}\)
• b. \(\text{OH}^-\) and \(\text{OH}_2^+\)
• c. \(\text{OH}^+\) and \(\text{H}^-\)
• d. \(\text{OH}^-\) and \(\text{H}_3\text{O}^+\) (Correct answer)

Question 108

• a. \(10^{-14}\text{ M}\)
• b. zero
• c. \(1 \times 10^{-7}\text{ M}\) (Correct answer)
• d. equal to \([\text{OH}^-]\)

Question 109

• a. acidic
• b. basic (Correct answer)
• c. neutral
• d. The type varies, depending on the solution.

Question 110

• a. polar covalent bonding
• b. complete ionization in water (Correct answer)
• c. ionic bonding
• d. presence of a hydroxide or hydrogen ion