Question 1

A BrØnsted- Lowry base is defined as a substance that .

Accepted Answer

A Brønsted-Lowry base is defined as a substance that acts as a proton acceptor.

Question 2

Classify the following compounds as weak acids (W) or strong acids (S):
Hypochlorous acid perchloric acid chloric acid

Accepted Answer

Hypochlorous acid is a weak acid, while perchloric acid and chloric acid are strong acids.

Question 3

An aqueous solution contains 0.10 M NaOH. The solution is _.

Accepted Answer

A solution containing 0.10 M NaOH is basic due to the presence of hydroxide ions (OH-) from the dissociation of NaOH in water.

Question 4

The base- dissociation constant of ethylamine (C₂H₅NH₂) is 6.4 × 10^-⁴at 25.0 °C. The of [H⁺] in a 1.6 × 10^-²M solution of ethylamine is M.

Accepted Answer

The base-dissociation constant (Kb) can be used to find the hydroxide ion concentration, and then the hydrogen ion concentration can be found using the relation Kw = [H+][OH-], where Kw = 1.0 × 10^-14 at 25°C. Solving for [H+] gives 3.5 × 10^-12 M.

Question 5

In which of the following aqueous solutions does the weak acid exhibit the highest percentage ionization?

Accepted Answer

The percentage ionization of a weak acid is determined by the equilibrium constant (Ka) of the dissociation reaction: 
HA + H2O ⇆ H3O+ + A-

The larger the value of Ka, the stronger the acid and the greater the percentage of the acid that dissociates. 
Among the options given, HF has the highest Ka value (6.8 × 10^-4) indicating that it is the strongest acid. Therefore, it will exhibit the highest percentage ionization.

Question 6

Of the compounds below, a 0.1 M aqueous solution of will have the highest pH.

Accepted Answer

KCN will have the highest pH because CN⁻ is a strong conjugate base of the weak acid HCN, leading to a more basic solution compared to the other options.

Question 7

The acid- dissociation constant at 25.0 °C for hypochlorous acid (HClO) is 3.0 × 10^-⁸. At equilibrium, the molarity of H₃O⁺in a 0.010 M solution of HClO is .

Accepted Answer

The balanced chemical equation for the dissociation of HClO is: HClO ⇌ H+ + ClO- The acid dissociation constant expression (Ka) for this reaction is: Ka = [H+][ClO-]/[HClO] At equilibrium, let x be the molarity of H+ and ClO-. Therefore, the molarity of HClO is (0.010 - x), because at the start there is C mol of HClO, there are zero mol of H+ and ClO-. At equilibrium, some fraction x of HClO will disassociate into H+ and ClO-. Using the given value of Ka, we can write: Ka = x^2/(0.010 - x) Solve for x: x = 1.7 × 10^-5 M Therefore, the molarity of H₃O⁺ in a 0.010 M solution of HClO is equal to [H+] = [ClO-] = 1.7 × 10^-5 M. Thus, the total molarity of H₃O⁺ (sum of H+ and ClO-) is 2 × 1.7 × 10^-5 = 3.4 × 10^-5 M. This is approximately equal to 1.7 × 10^-5 × 2, but not exactly due to an intermediate rounding step. Answer C, 1.7 × 10^-5 M, is the closest choice.

Question 8

A 0.1 M aqueous solution of will have a pH of 7.0 at 25.0 °C.

Accepted Answer

KCl is a neutral salt formed from a strong acid (HCl) and a strong base (KOH), so its solution will have a pH of 7.0.

Question 9

The concentration of water in pure water is approximately M.

Accepted Answer

The concentration of water in pure water is approximately 55 M (molar), calculated using the density of water (1 g/mL) and the molar mass of water (18 g/mol).

Question 10

Of the following acids, is not a strong acid.

Accepted Answer

HNO₂ is a weak acid, while H₂SO₄, HCl, HClO₄, and HNO₃ are all strong acids.

Question 11

Which of the following acids will be the strongest?

Accepted Answer

H₂SO₄ (sulfuric acid) is a strong acid, completely dissociating in water, making it stronger than the other options listed.

Question 12

The K_aof hypochlorous acid (HClO) is 3.0 × 10^-⁸at 25.0 °C. What is the % ionization of hypochlorous acid in a 0.015- M aqueous solution of HClO at 25.0 °C?

Accepted Answer

The equation for the ionization of hypochlorous acid is: 
HClO ⇌ H+ + ClO-
The equilibrium constant expression for this equation is: 
K = [H+][ClO-]/[HClO]
To find the % ionization, we need to calculate the concentration of H+ and ClO- ions at equilibrium, and then use these values to calculate the fraction of HClO that has ionized (i.e. formed H+ and ClO- ions).
Let x be the concentration of H+ and ClO- at equilibrium (since they are formed in a 1:1 ratio).
Then, [H+] = x
[ClO-] = x
And [HClO] = 0.015 M (initial concentration)
Substituting these values into the equilibrium constant expression and solving for x, we get: 
K = [H+][ClO-]/[HClO]
3.0 × 10^-8 = x^2/0.015
x^2 = 4.5 × 10^-10
x = 2.1 × 10^-5 M
The % ionization is then: 
% ionization = [(concentration of H+ + ClO-) / (initial concentration of HClO)] × 100%
% ionization = [(2.1 × 10^-5 M + 2.1 × 10^-5 M) / 0.015 M] × 100%
% ionization = 0.14%
Therefore, the correct answer is B) 0.14.

Question 13

A 0.0035- M aqueous solution of a particular compound has pH = 2.46. The compound is
)

Accepted Answer

The low pH of 2.46 indicates a high concentration of hydrogen ions, suggesting the compound is a strong acid.

Question 14

Which one of the following is a BrØnsted- Lowry acid?

Accepted Answer

All the given substances can donate a proton (H⁺) in a chemical reaction, which qualifies them as Brønsted-Lowry acids.

Question 15

A 0.1 M solution of has a pH of 7.0.

Accepted Answer

NaNO3 is a neutral salt formed from a strong acid (HNO3) and a strong base (NaOH), so it does not affect the pH of the solution, resulting in a pH of 7.0.

Question 16

The magnitude of K_windicates that .

Accepted Answer

The magnitude of K_w is the ion product constant of water, which represents the extent of autoionization of water. A value close to 1 indicates a high degree of autoionization, while a value close to 0 indicates a low degree of autoionization. The value of K_w is approximately 10^-14, which indicates that water autoionizes only to a very small extent.

Question 17

Calculate the molarity of hydroxide ion in an aqueous solution that has a pOH of 5.33.

Accepted Answer

pOH = -log[OH-]
5.33 = -log[OH-]
-5.33 = log[OH-]
10^-5.33 = [OH-]
[OH-] = 4.7 × 10^-6 M
Therefore, the molarity of hydroxide ion in the solution is 4.7 × 10^-6 M, which corresponds to answer choice D.

Question 18

The molar concentration of hydronium ion in pure water at 25°C is .

Accepted Answer

In pure water at 25°C, the concentration of hydronium ions (H₃O⁺) is 1.0 × 10⁻⁷ M due to the autoionization of water.

Question 19

A BrØnsted- Lowry acid is defined as a substance that .

Accepted Answer

A BrØnsted- Lowry acid is defined as a substance that donates a proton (H+) to another substance, which acts as a BrØnsted-Lowry base and accepts the proton. Therefore, choice C is the correct answer.

Question 20

Classify the following compounds as weak acids (W) or strong acids (S):

Accepted Answer

The answer of Classify the following compounds as weak acids...

Quiz 16: Acid-Base Equilibria

A BrØnsted- Lowry base is defined as a substance that .

Classify the following compounds as weak acids (W) or strong acids (S) : Hypochlorous acid perchloric acid chloric acid

An aqueous solution contains 0.10 M NaOH. The solution is _.

The base- dissociation constant of ethylamine (C₂H₅NH₂) is 6.4 × 10^-⁴at 25.0 °C. The of [H⁺] in a 1.6 × 10^-²M solution of ethylamine is M.

In which of the following aqueous solutions does the weak acid exhibit the highest percentage ionization?

Of the compounds below, a 0.1 M aqueous solution of will have the highest pH.

The acid- dissociation constant at 25.0 °C for hypochlorous acid (HClO) is 3.0 × 10^-⁸. At equilibrium, the molarity of H₃O⁺in a 0.010 M solution of HClO is .

A 0.1 M aqueous solution of will have a pH of 7.0 at 25.0 °C.

The concentration of water in pure water is approximately M.

Of the following acids, is not a strong acid.

Which of the following acids will be the strongest?

The K_aof hypochlorous acid (HClO) is 3.0 × 10^-⁸at 25.0 °C. What is the % ionization of hypochlorous acid in a 0.015- M aqueous solution of HClO at 25.0 °C?

A 0.0035- M aqueous solution of a particular compound has pH = 2.46. The compound is )

Which one of the following is a BrØnsted- Lowry acid?

A 0.1 M solution of has a pH of 7.0.

The magnitude of K_windicates that .

Calculate the molarity of hydroxide ion in an aqueous solution that has a pOH of 5.33.

The molar concentration of hydronium ion in pure water at 25°C is .

A BrØnsted- Lowry acid is defined as a substance that .

Classify the following compounds as weak acids (W) or strong acids (S) :

Quiz 16: Acid-Base Equilibria

A BrØnsted- Lowry base is defined as a substance that .

Classify the following compounds as weak acids (W) or strong acids (S) : Hypochlorous acid perchloric acid chloric acid

An aqueous solution contains 0.10 M NaOH. The solution is _.

The base- dissociation constant of ethylamine (C2H5NH2) is 6.4 × 10- 4 at 25.0 °C. The of [H+] in a 1.6 × 10- 2 M solution of ethylamine is M.

In which of the following aqueous solutions does the weak acid exhibit the highest percentage ionization?

Of the compounds below, a 0.1 M aqueous solution of will have the highest pH.

The acid- dissociation constant at 25.0 °C for hypochlorous acid (HClO) is 3.0 × 10- 8. At equilibrium, the molarity of H3O+ in a 0.010 M solution of HClO is .

A 0.1 M aqueous solution of will have a pH of 7.0 at 25.0 °C.

The concentration of water in pure water is approximately M.

Of the following acids, is not a strong acid.

Which of the following acids will be the strongest?

The Ka of hypochlorous acid (HClO) is 3.0 × 10- 8 at 25.0 °C. What is the % ionization of hypochlorous acid in a 0.015- M aqueous solution of HClO at 25.0 °C?

A 0.0035- M aqueous solution of a particular compound has pH = 2.46. The compound is )

Which one of the following is a BrØnsted- Lowry acid?

A 0.1 M solution of has a pH of 7.0.

The magnitude of Kw indicates that .

Calculate the molarity of hydroxide ion in an aqueous solution that has a pOH of 5.33.

The molar concentration of hydronium ion in pure water at 25°C is .

A BrØnsted- Lowry acid is defined as a substance that .

Classify the following compounds as weak acids (W) or strong acids (S) :

The base- dissociation constant of ethylamine (C₂H₅NH₂) is 6.4 × 10^-⁴at 25.0 °C. The of [H⁺] in a 1.6 × 10^-²M solution of ethylamine is M.

The acid- dissociation constant at 25.0 °C for hypochlorous acid (HClO) is 3.0 × 10^-⁸. At equilibrium, the molarity of H₃O⁺in a 0.010 M solution of HClO is .

The K_aof hypochlorous acid (HClO) is 3.0 × 10^-⁸at 25.0 °C. What is the % ionization of hypochlorous acid in a 0.015- M aqueous solution of HClO at 25.0 °C?

The magnitude of K_windicates that .