Chem II Exam 2- Quizzes

Determine the value of Kc for the following reaction A + B ↔ 2C if the equilibrium concentrations are found to be: A = 0.846 M B= 1.479 M C = 0.58 M

.27

Given the equilibrium reaction PCl5 (g) ↔ PCl3 (g) + Cl2 (g) Calculate the number of moles of Cl2 produced at equilibrium when 2.6 mol of PCl5 is heated at 283.9 deg celsius in a vessel having a capacity of 10.0L. At 283.9, K = 0.042 for this dissociation.

.86 moles

Determine the % ionization of 1 M hydrocyanic acid (HCN), Ka = 4.0 x 10-10

0.002%

What is the hydroxide concentration of a 1.28 M benzoic acid solution?

1.1E-12 M

A solution is prepared by diluting 0.055 mol HCl with water to a volume of 1.50 L. What is the pH of the solution?

1.44

What is the hydronium ion concentration of a 2.9 M NH3 solution?

1.4E-12 M

The pH of an aqueous 0.10 M basic solution is 9.09. What is the Kb of this base?

1.5 x 10-9

Two gases are added to a 1.00 L container: 2.0 moles of A; 4.0 moles of B. These gases react as follows: A(g) + 3 B(g) ⇔⇔ C(g) + 2 D(g) At equilibrium the container contains 0.6 moles of D. Calculate the concentration of A at equilibrium.

1.7 M

What is the pH of a 4.2 M solution of a weak base with Kb= 0.000030?

12.05

What is the pH of a 0.20 M Ca(OH)2 solution? (Strong base)

13.60

Nitrosyl bromide decomposes according to the chemical equation below. 2NOBr(g) ↔ 2NO(g) + Br2(g) When 0.260 atm of NOBr is sealed in a flask and allowed to reach equilibrium, 22% of the NOBr decomposes. What is the equilibrium constant, Kp, for the reaction?

2.27E-3

What is the hydronium ion concentration of a 3.3 M Aniline (C6H5NH2) solution?

2.7E-10 M

What is the ionization constant for the conjugate acid of a weak base with Kb = 0.000034?

2.9E-10

What is the [H3O+] in a 0.75 M NaF solution?

3.0 x 10-9 M

If Kc = 0.68 for this reaction 3H2(g) + N2(g) ⇔⇔ 2NH3(g) what is the value for Kc for the following reaction at the same temperature? 6NH3(g) ⇔⇔ 9H2(g) + 3N2(g)

3.2

What is the hydroxide concentration of a 0.379 M acetic acid solution?

3.9E-12 M

What is the hydronium concentration of a 0.3 M solution of NaCN?

4.04E-12 M

What is the hydroxide ion concentration of a 4.6 M Aniline (C6H5NH2) solution?

4.4E-5 M

What is the pH of a 0.0000043 M solution of hydrochloric acid?

5.37

What is the pH of a 0.75 M NaF solution?

8.52

What is the hydroxide ion concentration of a 4.2 M NH3 solution?

8.7E-3 M

What is the [H3O+] in a 0.50 M (CH3)3NHCl solution?

8.8 x 10-6 M

What is the hydronium ion concentration of a 1.41 M benzoic acid solution?

9.4E-3 M

Which compound is the weakest acid? a. HF b. HCl c. HBr d. HI

A

Which represents the strongest acid? Select one: a. Ka = 7.94 x 10-5 b. Ka = 3.98 x 10-8 c. Ka = 6.31 x 10-6 d. Ka = 3.16 x 10-7 e. Ka = 5.01 x 10-9

A

Which represents the strongest acid? Select one: a. ΔGo = -15 kJ b. ΔGo = 5 kJ c. ΔGo = 0 d. ΔGo = -5 kJ e. ΔG = 15 kJ

A

Which statement explains why HBr is a stronger acid than HF? a. Br- is more stable than F- because Br- is larger than F-. b. Br- is less stable than F- because Br- is larger than F-. c. Br- is more stable than F- because Br- is less electronegative than F-. d. Br- is less stable than F- because Br- is less electronegative than F-.

A

Indicate which are potential acids. a. HPO42- b. NH4+ c. CH3NH3+ d. H2O e. Al3+ f. F-

A, B, C, D, E

Which acid would have the largest positive change in G? a. Hydrofluoric, Ka= 3.5E-4 b. Formic, Ka= 1.8E-4 c. Benzoic, Ka= 6.5E-5 d. Acetic, Ka= 1.8E-5

Acetic

Identify 0.1 M solutions of each compound is acidic, basic, or neutral H2S

Acidic

Identify 0.1 M solutions of each compound is acidic, basic, or neutral HCl

Acidic

Identify 0.1 M solutions of each compound is acidic, basic, or neutral NH4Cl

Acidic

Identify 0.1 M solutions of each compound is acidic, basic, or neutral NH4NO3

Acidic

Which compound is the strongest acid?

B

Which compound is the strongest acid? a. CH3OH b. BrCH2OH c. CH3NH2 d. CH3Cl

B

Which ionic compound forms a pH-neutral aqueous solution at 25 °C? a. LiHCO3 b. KNO3 c. MgF2 d. NH4Br e. Na2S

B

Which of the following is a strong acid? a. H3PO4 b. HNO3 c. HF d. CH3COOH e. H2O

B

Indicate which are potential bases. a. CH3NH3+ b. HPO42- c. H2O d. Al3+ e. F- f. NH4+

B, C, E

Identify 0.1 M solutions of each compound is acidic, basic, or neutral KCN

Basic

Identify 0.1 M solutions of each compound is acidic, basic, or neutral KNO2

Basic

Identify 0.1 M solutions of each compound is acidic, basic, or neutral LiF

Basic

Identify 0.1 M solutions of each compound is acidic, basic, or neutral Na3PO4

Basic

Identify 0.1 M solutions of each compound is acidic, basic, or neutral NaF

Basic

Identify 0.1 M solutions of each compound is acidic, basic, or neutral NaHCO3

Basic

Identify 0.1 M solutions of each compound is acidic, basic, or neutral CH3COONa

Basic

Identify 0.1 M solutions of each compound is acidic, basic, or neutral.= Na2S

Basic

If 0.10 M aqueous solutions are prepared of each of the acids, which produces the solution with the highest pH? a. formic acid b. nitrous acid c. hypochlorous acid d. hydrogen sulfite ion e. phosphoric acid

C

Which compound is the weakest acid? a. H2S b. PH3 c. HCl d. SiH4

D

Which equation below best describes the expression for the ion product constant (Kw) for the dissociation of water? A. Kw = BLT = YUM B. Kw = [H+]/[OH-] = 1x10^-14 C. Kw = [H+][OH-]/[H2O] = 55.5 D. Kw = [H+][OH-] = 1x10^-14

D

Which molecule or ion is amphoteric (can behave as both an acid or base) in water? a. NH4+ b. F- c. CH3CO2H d. HC2O4- e. CO32-

D

Which statement about acid strength is true? a. The stronger the acid, the further the equilibrium lies to the left. b. The stronger the acid, the smaller the Ka. c. The stronger the acid, the larger the pKa. d. The stronger the acid, the smaller the pKa.

D

Which statement is INCORRECT? a. H3PO4 is a stronger acid than H2PO4-. b. HClO3 is a stronger acid than HClO2. c. HNO3 is a stronger acid than HNO2. d. HOBr is a stronger acid than HOCl.

D

Which is the potential energy diagram of the weakest acid?

Greatest G increase

Which species is the conjugate acid of ammonia, NH3?

H4N+

Which concept can be used to explain the difference in acidity between acetylene (C2H2) and ethylene (C2H4)?

Hybridization

Rank compounds in order of increasing acidity, putting the least acidic first.

III < IV < I < II

Consider the molecule with protons labeled, I-III. Rank these protons in order of decreasing acidity, putting the most acidic first.

III > II > I

Rank compounds in order of decreasing acidity, putting the most acidic first.

III > IV > II > I

Which concept can be used to explain the difference in acidity between ethanol (CH3CH2OH) and 2-fluoroethanol (FCH2CH2OH)?

Inductive Effect

Write the expression for Kp for the reaction below. 2 NOBr(g) <-> 2 NO(g) + Br2(l)

KP= (P2NO)/(P2NOBr)

Write the expression for Kp for the reaction below. MgCO3(s) MgO(s) + CO2(g)

KP= P(CO2)

Identify 0.1 M solutions of each compound is acidic, basic, or neutral LiCLO4

Neutral

Identify 0.1 M solutions of each compound is acidic, basic, or neutral NaCl

Neutral

Identify 0.1 M solutions of each compound is acidic, basic, or neutral.= NaNO3

Neutral

Which concept can be used to explain the difference in acidity between acetic acid (CH3COOH) and ethanol (CH3CH2OH)?

Resonance

Consider the reaction A(aq) <-> 2 B(aq) where Kc = 4.1 at 25 °C. If 0.50 M A(aq) and 1.5 M B(aq) are in a flask, predict the direction of the equilibrium as the reaction is reaching equilibrium by using Q, the reaction quotient.

Reverse because Q > K

Given the following system at equilibrium: N2(g) + 2O2(g) ↔ 2NO2 (g) + heat What is the effect on the equilibrium if you add a catalyst?

The equilibrium will not shift

Given the following system at equilibrium: N2(g) + 2O2(g) ↔ 2NO2 (g) + heat What is the effect on the equilibrium if you increase the concentration of oxygen?

The equilibrium will shift towards products.

A 2.5 L flask is filled with 0.25 mol SO3, 0.20 mol SO2, and 0.40 mol O2, and allowed to reach equilibrium. Assume the temperature of the mixture is chosen so that Kc = 0.12. Predict the effect on the concentration of SO3 as equilibrium is achieved by using Q, the reaction quotient. 2SO3(g) ↔ 2SO2(g) + O2(g)

[SO3] will decrease because Q < K

Which acid has the most positive ΔGo? Select one: a. pKa = 5.2 b. pKa = 8.3 c. pKa = 7.4 d. pKa = 6.5 e. pKa = 4.1

b. pKa = 8.3

In which equilibrium system(s) will an increase in the pressure cause the reaction to shift to the right? Select one or more: a. H2(g) + F2(g) <-> 2 HF(g) b. N2(g) + 3 H2(g) <-> 2 NH3(g) c. CaCO3(s) <-> CaO(s) + CO2(g) d. 2 NOBr(g) <-> 2 NO(g) + Br2(g) e. 2 H2O(g) + O2(g) <-> 2 H2O2(g)

d. N2(g) + 3 H2(g) >-> 2 NH3(g) e. 2 H2O(g) + O2(g) <-> 2 H2O2(g)