ChemFinal

An Arrhenius acid is best defined as a

substance that dissociates in water to produce aqueous hydrogen ions.

When dissolved in water, which of the following compounds is an Arrhenius acid?

HCN

An Arrhenius base is best defined as a

substance that dissociates in water to produce aqueous hydroxide ions.

When dissolved in water, which of the following compounds is an Arrhenius base?

KOH

A Brønsted-Lowry acid is best defined as a substance that can

donate a proton.

Which one of the following species acts as a Brønsted-Lowry acid in water?

NH4+

In the following chemical equation indicate the reactant that is a Brønsted-Lowry acid

HCN(aq) + H2O(l) ⇌ H3O+(aq) + CN-(aq).

HCN

Indicate all the Brønsted-Lowry acids in the following chemical reaction

HCl(aq) + H2O(aq) ⇌ H3O+(aq) + Cl-(aq).

HCl,

What are the Brønsted-Lowry bases in the following chemical reaction

C5H5N(aq) + H2O(l) ⇌ C5H5NH+(aq) + OH-(aq)?

C5H5N,

What are the Brønsted-Lowry acids in the following chemical reaction

HBr(sol) + CH3COOH(sol) ⇌ CH3C(OH)2+(sol) + Br-(sol)?

HBr,

What are the conjugate acid-base pairs in the following chemical reaction

NH3(aq) + H2O(l) ⇌ NH4+(aq) + OH-(aq)?

NH3, NH4+ and H2O, OH-

Identify the conjugate acid/base pairs present in an aqueous solution of hydrogen sulfate ion, HSO4-.

HSO4-/SO42- and H3O+/H2O

What is the conjugate base of the Brønsted-Lowry acid HPO42-?

PO43-

What is the conjugate acid of the Brønsted-Lowry base HAsO42-?

H2AsO4-

Which one of the following can behave either as a Brønsted-Lowry acid or a Brønsted-Lowry base in an aqueous solution reaction?

HSO3-

Write a balanced equation for the dissociation of the Brønsted-Lowry acid HSO4- in water.

HSO4-(aq) + H2O(l) ⇌ SO42-(aq) + H3O+(aq)

Which of the following Brønsted-Lowry acids does not behave as a strong acid when it is dissolved in water?

HNO2

Which Brønsted -Lowry base has the strongest conjugate acid?

NO3-

Which Brønsted-Lowry acid has the strongest conjugate base?

HF

What is the strongest Brønsted-Lowry acid in the chemical reaction shown below?

2 HNO3(aq) + Ba(OH)2(aq) → Ba(NO3)2(aq) + 2 H2O(l)

HNO3

From the following chemical reactions determine the relative Brønsted-Lowry acid strengths (strongest to weakest).

HCl(aq) + H2O(l) → H3O+(aq) + Cl-(aq)

HCN(aq) + H2O(l) ⇌ H3O+(aq) + CN-(aq)

HCl > H3O+ > HCN

From the following chemical reactions determine the relative Brønsted-Lowry acid strengths (strongest to weakest).

HClO4(aq) + H2O(l) → H3O+(aq) + ClO4-(aq)

HNO2(aq) + H2O(l) ⇌ H3O+(aq) + NO2-(aq)

HClO4 > H3O+ > HNO2

From the following chemical reactions determine the relative Brønsted-Lowry acid strengths (strongest to weakest).

HClO4(sol) + CH3COOH(l) → CH3C2(OH)2+(sol) + ClO4-(aq)

H2SO4(sol) + CH3COOH(l) ⇌ CH3C(OH)2+(sol) + HSO4-(sol)

HClO4 > CH3C(OH)2+ > H2SO4

From the following chemical reactions determine the relative Brønsted-Lowry base strengths (strongest to weakest).

HNO3(aq) + H2O(l) → H3O+(aq) + NO3-(aq)

HF(aq) + H2O(l) ⇌ H3O+(aq) + F-(aq)

F- > H2O > NO3-

From the following chemical reactions determine the relative Brønsted-Lowry base strengths (strongest to weakest).

2 NaH(s) + H2O(l) → 2 NaOH + H2(g)

NH3(aq) + H2O(l) ⇌ NH4+(aq) + OH-(aq)

H- > OH- > NH3

The equilibrium constant, K, for the reaction shown below has a value 1.8 × 10-5. In this reaction which is the strongest acid and which is the strongest base?

CH3CO2H(aq) + H2O(l) ⇌ H3O+(aq) + CH3CO2-(aq)

H3O+ and CH3CO2-

The following pictures represent aqueous solutions of binary acids of the type HA where the water molecules have been omitted for clarity.

Determine the strongest acid of the set.

B

Arrange the acids in order of increasing acid strength.

D < A < C < B

What is the geometric shape of the hydrated proton; that is, the hydronium ion H3O+?

trigonal pyramidal

An acidic solution at 25°C has

[H3O+] > 1 × 10-7 M > [OH-].

At 50°C the value of Kw is 5.5 × 10-14. A basic solution at 50°C has

[H3O+] < 2.3 × 10-7 M < [OH-].

Calculate the hydronium ion concentration in an aqueous solution that contains 2.50 × 10-4 M in hydroxide ion.

4.00 × 10-11 M

Calculate the hydroxide ion concentration in an aqueous solution that contains 3.50 × 10-3 M in hydronium ion.

2.86 × 10-12 M

A solution with a hydrogen ion concentration of 3.25 × 10-2 M is and has a hydroxide concentration of .

acidic, 3.08 × 10-13 M

A solution with a hydroxide ion concentration of 4.15 × 10-4 M is and has a hydrogen ion concentration of .

basic, 2.41 × 10-11 M

If the ionization constant of water, Kw, at 40°C is 2.92 × 10-14, then what is the hydronium ion concentration for a neutral solution?

[H3O+] = 1.71 × 10-7 M

An acidic solution at 25°C will have a hydronium ion concentration and a pH value .

[H3O+] > 1 × 10-7 M, pH < 7.00

If the ionization constant of water, Kw, at 40°C is 2.92 × 10-14, then what is the hydronium ion concentration and pH for an acidic solution?

[H3O+] > 1.71 × 10-7 M and pH < 6.77

Calculate the pH for an aqueous solution of acetic acid that contains hydronium ion.

2.67

Calculate the pH for an aqueous solution of pyridine that contains hydroxide ion.

10.33

What is the hydroxide ion concentration and the pH for a hydrochloric acid solution that has a hydronium ion concentration of

6.67 × 10-11 M, 3.82

What is the hydronium ion concentration and the pH for an aqueous solution of NH3 that has a hydroxide ion concentration of

4.44 × 10-12 M, 11.35

hat is the hydronium ion concentration of an acid rain sample that has a pH of 3.15?

7.08 × 10-4 M

What is the hydroxide ion concentration of a lye solution that has a pH of 11.20?

1.58 × 10-3 M

What statement is most consistent for an acid with a pH = 3?

one hundred times as strong as an acid with a pH = 5

At 25°C, the pH of a vinegar solution is 2.60. What are the values of [H3O+] and [OH-] in the solution?

2.51 × 10-3 M, 3.98 × 10-12 M

What is the approximate pH of a solution X that gives the following responses with the indicators shown?

6.0 - 7.6

What is the approximate pH of a solution X that gives the following responses with the indicators shown?

Indicators HIn — In- pH range Solution X

methyl orange red-yellow 3.2-4.4 yellow

methyl red red-yellow 4.8-6.0 orange

bromthymol blue yellow-blue 6.0-7.6 yellow

phenolphthalein colorless-pink 8.2-10.0 colorless

4.8 - 6.0

What is the approximate pH of a solution X that gives the following responses with the indicators shown?

Indicators HIn — In- pH range Solution X

methyl orange red-yellow 3.2-4.4 yellow

methyl red red-yellow 4.8-6.0 yellow

bromthymol blue yellow-blue 6.0-7.6 blue

phenolphthalein colorless-pink 8.2-10.0 pink

8.2

What is the pH of a 0.020 M HClO4 solution?

1.70

What is the pH of a 0.020 M RbOH solution?

12.30

What is the pH of a 0.020 M Ba(OH)2 solution?

12.60

What is the pH of a solution prepared by dissolving 0.15 gram of solid CaO (lime) in enough water to make 2.00 L of aqueous Ca(OH)2 (limewater)?

CaO(s) + H2O(l) → Ca2+(aq) + 2 OH-(aq)

11.43

) What is the pH of a solution prepared by diluting 25.00 mL of 0.10 M HCl with enough water to produce a total volume of 100.00 mL?

1.60

What is the pH of a solution prepared by diluting 25.00 mL of 0.020 M Ba(OH)2 with enough water to produce a total volume of 250.00 mL?

11.60

What is the pH of a solution made by mixing 100.00 mL of 0.20 M HCl with 50.00 mL of 0.10 M HCl? Assume that the volumes are additive.

0.78

What is the pH of a solution made by mixing 100.0 mL of 0.10 M HNO3, 50.0 mL of 0.20 M HCl, and 100.0 mL of water? Assume that the volumes are additive.

1.10

What is the pH of a solution prepared by mixing 100.00 mL of 0.020 M Ca(OH)2 with 50.00 mL of 0.100 M NaOH? Assume that the volumes are additive.

12.78

What is the equilibrium constant expression (Ka) for the acid dissociation of hydrocyanic acid HCN? The equation of interest is

HCN(aq) + H2O(l) ⇌ H3O+(aq) + CN-(aq).

Ka = ([H3O+][CN-])/([HCN])

What is the equilibrium constant expression (Ka) for the acid dissociation of nitrous acid HNO2? The equation of interest is

HNO2(aq) + H2O(l) ⇌ H3O+(aq) + NO2-(aq).

([H3O+][NO2-])/([HNO2])

Determine the acid dissociation constant for a 0.10 M acetic acid solution that has a pH of 2.87. Acetic acid is a weak monoprotic acid and the equilibrium equation of interest is

1.8 × 10-5

Determine the acid dissociation constant for a 0.010 M nitrous acid solution that has a pH of 2.70. Nitrous acid is a weak monoprotic acid and the equilibrium equation of interest is

5.0 × 10-4

Determine the acid dissociation constant for a 0.020 M formic acid solution that has a pH of 2.74. Formic acid is a weak monoprotic acid and the equilibrium equation of interest is

1.8 × 10-4

The pH of 0.255 M HCN is 4.95. What is the value of Ka for hydrocyanic acid?

4.9 × 10-10