Exam 3

Which one of the following will change the value of an equilibrium constant? A. Changing temperature B. Varying initial concentration of products C. Adding other substances that do not react with any of the species involved D. Varying the initial concentration of reactants E. Changing the volume of the reaction vessel

A. Changing temperature

Of the following acids, ____ is not a strong acid. A. HNO₂ B. H₂SO₄ C. HNO₃ D. HClO₄ E. HCl

A. HNO₂

Which of the following expressions is the correct equilibrium-constant expression for the equilibrium between dinitrogen tetroxide and nitrogen dioxide? N2O4 (g) ⇌ 2NO2 (g) A. [NO2]²/[N2O4] B. [NO2]/[N2O4]² C. [NO2]²[N2O4] D. [NO2][N2O4] E. [NO2]/[N2O4]

A. [NO2]²/[N2O4]

2SO2 (g) + O2 (g) 2SO3 (g) Le Chatelier's Principle predicts that __________ will result in an increase in the number of moles of SO3 (g) in the reaction container. A. increasing the pressure B. increasing the volume of the container C. removing some oxygen D. decreasing the pressure E. increasing the temperature

A. increasing the pressure

According to the Arrhenius concept, an acid is a substance that _____. A. is capable of donating one or more H⁺ B. can accept a pair of electrons to form a coordinate covalent bond C. reacts with solvent to form the cation formed by the auto-ionization of that solvent. D. causes an increase in the concentration of H⁺ in aqueous solutions E. tastes bitter

A. is capable of donating one or more H⁺

What is the pH of a 0.0150 M aqueous solution of barium hydroxide? A. 12.2 B. 12.5 C. 1.82 D. 1.52 E. 10.4

B. 12.5

Of the compounds below, a 0.1 M aqueous solution of ____ will have the highest pH. A. NaClO, Ka of HClO = 3.2 x 10⁻⁸ B. KCN, Ka of HCN = 4.0 x 10⁻⁷ C. NaHS, Kb of HS⁻ = 1.8 x 10⁻⁷ D. NaOAc, Ka of HOAc = 1.8 x 10⁻⁵ E. NH₄NO₃, Kb of NH₃ = 1.8 x 10⁻⁵

B. KCN, Ka of HCN = 4.0 x 10⁻⁷

Ammonia is a ________. A. Weak Acid B. Weak Base C. Salt D. Strong Acid E. Strong Base

B. Weak Base

2CO2 (g) 2CO (g) + O2 (g) ΔH° = -514 kJ Le Chatelier's principle predicts that an increase in temperature will __________. A. increase the partial pressure of CO B. decrease the value of the equilibrium constant C. decrease the partial pressure of CO2 (g) D. increase the value of the equilibrium constant E. increase the partial pressure of O2 (g)

B. decrease the value of the equilibrium constant

Which solution below has the highest concentration of hydroxide ions? A. pH = 7 B. pH = 12.6 C. pH = 9.82 D. pH = 7.93 E. pH = 3.21

B. pH = 12.6

The magnitude of Kw indicated that _____. A. the auto-ionization of water is exothermic B. water auto-ionizes only to a very small extent C. water auto-ionizes very quickly D. Water auto-ionizes very slowly

B. water auto-ionizes only to a very small extent

The value of Keq for the following reaction is 0.25: SO2 (g) + NO2 (g) SO3 (g) + NO (g) The value of Keq at the same temperature for the reaction below is __________. 2SO2 (g) + 2NO2 (g) 2SO3 (g) + 2NO (g) A. 0.12 B. 0.25 C. 0.062 D. 0.50 E. 16

C. 0.062

Ka of HF at 25°C is 6.8 x 10⁻⁴. What is the pH of a 0.35 M aqueous solution of HF? A. 12 B. 3.2 C. 1.8 D. 3.6 E. 0.46

C. 1.8

The Keq for the equilibrium below is 7.52 × 10-2 at 480 °C. 2Cl2 (g) + 2H2O (g) ⇌ 4HCl (g) + O2 (g) What is the value of Keq at this temperature for the following reaction? 2HCl (g) + 1/2 O₂ (g) ⇌ Cl₂ (g) + H₂O (g) A. -0.0376 B. 0.274 C. 3.65 D. 13.3 E. 5.66

C. 3.65

The base-dissociation constant, Kb, for pyridine, C₅H₅N, is 1.4 x 10⁻⁹. The Ka for pyridinium, C₅H₅NH⁺ is _____. A. 1.4 x 10⁻²³ B. 1.0 x 10⁻⁷ C. 7.1 x 10⁻⁶ D. 1.4 x 10⁻⁵ E. 7.1 x 10⁻⁴

C. 7.1 x 10⁻⁶

2NH₃ ⇌ N₂ (g) + 3 H₂ (g) DeltaH = +92.4 kJ Le Chateliers principle predicts that adding N₂ (g) to the system at equilibrium will result in: A. Removal of all H₂ (g) B. An increase in the value of the equilibrium constant. C. Decrease in H₂ (g) concentration D. Decrease in NH₃ (g) concentration E. Lower partial pressure of N₂ (g)

C. Decrease in H₂ (g) concentration

Which one of the following is true concerning the Haber process? A. It is another way of stating Le Chatelier's principle. B. It is a process used for shifting equilibrium positions to the right for more economical chemical synthesis of a variety of substances. C. It is a process used for the synthesis of ammonia. D. It is a process for the synthesis of elemental chloride. E. It is an industrial synthesis of sodium chloride that was discovered by Karl Haber.

C. It is a process used for the synthesis of ammonia.

In which of the following reactions would increasing pressure at constant temperature not change the concentrations of reactants and products, based on Le Chatelier's principle? A. 2N2 (g) + O2 (g) 2N2O (g) B. N2 (g) + 3H2 (g) 2NH3 (g) C. N2 (g) + O2 (g) 2NO (g) D. N2O4 (g) 2NO2 (g) E. N2 (g) + 2O2 (g) 2NO2 (g)

C. N2 (g) + O2 (g) 2NO (g)

N2 (g) + 3H2 (g) 2NH3 (g) is Keq = 4.34 × 10-3 at 300 °C. At equilibrium, __________. A. roughly equal amounts of products and reactants are present B. products predominate C. reactants predominate D. only reactants are present E. only products are present

C. Reactants Predominate

At equilibrium, __________. A. all chemical reactions have ceased B. the rate constants of the forward and reverse reactions are equal C. the rates of the forward and reverse reactions are equal D. the value of the equilibrium constant is 1 E. the limiting reagent has been consumed

C. the rates of the forward and reverse reactions are equal

CaCO3 (s) CaO (s) + CO2 (g) Le Chatelier's principle predicts that __________ will result in an increase in the number of moles of CO2. A. decreasing the temperature B. removing some of the CaCO3 (s) C. increasing the pressure D. increasing the temperature E. adding more CaCO3 (s)

D. increasing the temperature

The equilibrium-constant expression depends on the __________ of the reaction. A. the quantities of reactants and products initially present B. stoichiometry and mechanism C. mechanism D. stoichiometry E. temperature

D. stoichiometry

A Bronsted-Lowry base is defined as a substance that _____. A. Increases [H+] when placed in H₂O B. Increases [OH-] when placed in H₂O C. Acts as a proton donor D. Decreases [H+] when placed in H₂O E. Acts as a proton acceptor

E. Acts as a proton acceptor

Which of the following is a Bronsted-Lowry Acid? A. CH₃COOH B. HNO₂ C. (CH₃)₃NH+ D. HF E. All of the above

E. All of the above

A substance that is capable of acting as both an acid and a as a base is: A. Saturated B. Miscible C. Conjugated D. Autosomal E. Amphoteric

E. Amphoteric

An aqueous solution of ________ will produce a basic solution. A. NaCl B. NaHSO₄ C. KBr D. NH₄ClO₄ E. Na₂SO₃

E. Na₂SO₃

How does the reaction quotient of a reaction differ from the equilibrium constant of the same reaction? A. Q does not change with temperature. B. Q does not depend on the concentrations or partial pressures of reaction components. C. K does not depend on the concentrations or partial pressures of reaction components. D. Keq does not change with temperature, whereas Q is temperature dependent. E. Q is the same as Keq when a reaction is at equilibrium.

E. Q is the same as Keq when a reaction is at equilibrium.

Consider the following reaction at equilibrium: 2NH3 (g) N2 (g) + 3H2 (g) Le Chatelier's principle predicts that the moles of H2 in the reaction container will increase with __________. A. some removal of NH3 from the reaction vessel (V and T constant) B. an increase in total pressure by the addition of helium gas (V and T constant) C. addition of some N2 to the reaction vessel (V and T constant) D. a decrease in the total volume of the reaction vessel (T constant) E. a decrease in the total pressure (T constant)

E. a decrease in the total pressure (T constant)