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General Chemistry 2 Practice Lecture Final Questions

Terms in this set (102)

In a reaction mixture containing only products, what is the value of Q?
c. Infinite
Consider the following reaction at equilibrium. What effect will increasing the temperature have on the system?

C3H8(g) + 5 O2(g) ⇌ 3 CO2(g) + 4 H2O(l) ΔH° = -2220 kJ
c. The reaction will shift to the left in the direction of reactants.
Define Le Chatelier's principle
b. When a chemical system at equilibrium is disturbed, the system shifts in a direction that minimizes the disturbance
Give the direction of the reaction, if K >> 1.
e. Forward reaction is favored
The Kp for the reaction below is 1.49 * 10^8 at 100.0°C

CO(g) + Cl2(g) ⇌ COCl2(g)

In an equilibrium mixture of the three gases, PCO = PCl2 = 2.22 × 10-4 atm. The partial pressure of the product, phosgene (COCl2), is ________ atm.
e. 7.34
What is Δn for the following equation in relating Kc to Kp?

N2(g) + 3 H2(g) ⇌ 2 NH3(g)
a. -2
The reaction below has Kc value of 61. What is the value of Kp for this reaction at 400 K?

N2(g) + 3 H2(g) ⇌ 2 NH3(g)
d. 5.7 * 10^-2
Phosphorous trichloride and phosphorous pentachloride equilibrate in the presence of molecular chlorine according to the reaction:

PCl3(g) + Cl2(g) ⇌ PCl5(g)

An equilibrium mixture at 450 K containsPPCl3 = 0.124 atm,PCl2 = 0.157 atm, andPPCl5 = 1.30 atm. What is the value of Kp at this temperature?
d. 66.7
Identify the products that are in equilibrium with NH3 and H2O.
b. NH4+ and -OH
Which of the following is true?
d. An acidic solution has [H3O⁺] > [OH⁻].
Identify the strong diprotic acid
b. H2SO4
Identify the weakest acid
b. HF
What is the hydronium ion concentration of an acid rain sample that has a pH of 3.45?
b. 3.55 *10-4 M
Calculate the hydroxide ion concentration in an aqueous potassium hydroxide solution that contains 3.50 x 10^-6 M in hydronium ion.
c. 2.86 * 10^-9 M
What is the hydroxide ion concentration and the pH for a hydrochloric acid solution that has a hydronium ion concentration of 1.50 *10^-2 M?
d. 6.67 *10^-13 M, 1.82
Which one of the following salts, when 1 mole is dissolved in water, produces the solution with the lowest pH?
e. H2SO4
When a diprotic acid titrated with a strong base, and the Ka1 and Ka2 are significantly different, then the pH vs. volume plot of the titration will have
e. two distinct equivalence points
Which of the following is TRUE?
c. The equivalence point is where the amount of acid equals the amount of base during any acid-base titration
A complex ion contains
e. a central metal ion bound to one or more ligands
Identify the cation that is NOT amphoteric
a. Fe2+
Calculate the pH of a solution that is 0.210 M in nitrous acid (HNO2) and 0.290 M in potassium nitrite (KNO2). The acid dissociation constant of nitrous acid is 4.50*10^-4
a. 3.487
A 25.0 mL sample of 0.150 M hydrazoic acid is titrated with a 0.150 M NaOH solution. What is the pH after 26.0 mL of base is added? The Ka of hydrazoic acid is 1.9 *10^-5
e. 11.47
What is the molar solubility of calcium carbonate (CaCO3) in water? The solubility product constant for CaCO3 is 4.5 * 10^-9 at 25°C.
a. 6.7 *10^-5
0.10 M potassium chromate is slowly added to a solution containing 0.50 M AgNO3 and 0.50 M Ba(NO3)2. What is the Ag+ concentration when BaCrO4 just starts to precipitate? The Ksp for Ag2CrO4 and BaCrO4 are 1.1 10^-12 and 1.2 10^-10, respectively
6.8 *10^-2 M
Place the following in order increasing molar entropy at 298 K.

NO CO SO
e. CO < NO < SO
Identify the statement that is FALSE.
c. Free atoms have greater entropy than molecules
What is true if In K is positive?
c. ΔG°rxn is negative and the reaction is spontaneous in the forward direction.
Identify the process in which the entropy increases.
e. the phase transition from a solid to a gas.
In the Haber process, ammonia is synthesized from a nitrogen and hydrogen:

N2(g) + 3 H2(g) → 2 NH3(g)

ΔG° at 298 K for this reaction is -33.3 kJ/mol. The value of ΔG at 298 K for a reaction mixture that consists of 1.9 atm N2, 1.6 atm H2, and 0.65 atm NH3 is ________.
b. -40.5
Consider the following reaction at constant P. Use the information here to determine the value of ΔSsurr at 398 K. Predict whether or not this reaction will be spontaneous at this temperature.

4 NH3(g) + 3 O2(g) → 2 N2(g) + 6 H2O(g) ΔH = -1267 kJ
c. ΔSsurr = +3.18 kJ/K, reaction is spontaneous
Determine the equilibrium constant for the following reaction at 655 K.

HCN(g) + 2 H2(g) → CH3NH2(g) ΔH° = -158 kJ; ΔS°= -219.9 J/K
b. 13.0
Under which of the following conditions would one mole of Ar have the highest entropy, S?
c. 167°C and 101 L
In a hydrogen-oxygen fuel cell,
e. oxygen atoms gain electrons and hydrogen atoms lose electrons
In a lead-acid storage battery, PbO2 is reduced to
c. PbSO4
An electrolytic cell
c. consumes electrical current a drive a nonspontaneous chemical reaction
Identify the battery that is used as a common flashlight battery
a. dry-cell battery
Balance the following redox reaction if it occurs in H2SO4. What are the coefficients in front of and H2SO4 in the balanced reaction?

C10H22O2(aq) + Na2Cr2O7(aq) → C10H18O4(aq) + Cr2(SO4)3(aq)
c. C10H22O2 = 3, H2SO4 = 16
How many grams of nickel metal are plated out when a constant current of 15.0 A is passed through aqueous NiCl for 60.0 minutes?
b. 16.4 g
A galvanic cell consists of Ni2+/Ni half-cell and a standard hydrogen electrode. If the Ni2+/Ni half-cell standard cell functions as the anode, and the standard cell potential is 0.26 V, what is the standard reduction potential for the Ni2+/Ni half-cell?
b. -0.26 V
What is the shorthand notation that represents the following galvanic cell reaction?

Pb(s)+Cu(NO3)2(aq)>>> Pb(NO3)2(aq) + Cu(s)
Pb(s) Pb2+(aq) Cu2+(aq) Cu(s)
Consider the following reaction at equilibrium. What effect will increasing the pressure of the reaction mixture have on the system?

2 H2S (g) + 3 O2 (g) , 2 H2O (g) + 2 SO2 (g)
c. The reaction will shift to the right in the direction of products
Which of the following statements is FALSE?
e. K >> implies that the reaction is very fast at producing products
Consider the following reaction equilibrium. What will happen if Fe2O3 is added to the reaction?

4 FeS2 (s) + 11 O2 (g), 2 Fe2O3 (s) + 8 SO2 (g)
d. The equilibrium will change in the direction of the reactants.
Give the direction of the reactants, if K >> 1.
d. The forward reaction is favored
For the reaction: N2 (g) + 2 O2 (g) , 2 NO2 (g), Kc = 8.3 * 10^-10 at 25°C. What is the concentration of N2 gas at equilibrium when the concentration of NO2 is five times the concentration of O2 gas?
d. 3.0 * 10^10 M
The equilibrium constant is given for one of the reactions below. Determine the value of the missing equilibrium constant.

N2O4 (g) , 2NO2 (g) Kc = 1.46
3 N2O4 (g), 6 NO2 (g) Kc = ?
b. 1.46
The equilibrium constant is given for one of the reactions below.
Determine the value of the missing equilibrium constant.

2HD (g) , H2 (g) + D2(g) Kc = 0.28
5 H2 (g) + 5 D2 (g) , 10 HD (g) Kc =?
e. 581
Determine the value of Kp for the following reaction if the equilibrium concentrations are as follows : P(NOCI)eq = 0.22 atm, P(NO)eq = 0.10 atm, P(CI2)eq = 0.11 atm

2 NOCI(g), 2 NO(g) + CI2(g)
c. 2.3 *10^-2
What is the conjugate acid of HCO3-?
a. H2CO3
The stronger the acid, then which of the following is TRUE?
e. the weaker the conjugate base
Place the following in order of increasing acid strength.

HBrO2, HBrO3, HBrO, HBrO4
e.HBrO < HBrO2 < HBrO3 <HBrO4
An Arrhenius acid
c. produces H+ in aqueous solutions
Which one of the following salts, when 1 mole is dissolved in water, produces the solution with a pH closest to 7.00?
e. NaHSO4
Which of the following acids is the strongest? The acid is followed by its Ka value.
e. HCIO2, 1.1 *10^-2
Calculate the pH of a solution that contains 2.4 * 10^-5 M H3O+ at 25°C.
b. 4.62
The pH of an aqueous solution at 25.0 C is 10.66. What is the molarity of H+ in this solution?
a. 2.2 * 10^-11
When titrating a weak base with HCI at 25°C, the
e. pH will be less than 7 at the equivalence point
Identify the ion that is less soluble in acidic water
b. NH4+
Which of the following solutions is a good buffer system?
c. a solution that is 0.10 M HCN and 0.10 M LiCN
Identify a good buffer
b. significant amounts of both a weak acid and its conjugate base
Which of the following acids (listed with Ka values) and their conjugate base would form a buffer with a pH of 2.34?
c. HCIO2, Ka = 1.1 *10^-2
The largest change in pH for an effective buffer occurs when the base is how many times as concentrated as the acid?
b. 10
A 200.0 mL sample of 0.20 M HF is titrated with 0.10 M NaOH. Determine the pH of the solution before the addition of any NaOH. The Ka of HF is 3.5 * 10^-4.
d. 2.08
Give the expression for the solubility product constant for Ca3(PO4)2
c. [Ca2+]3[PO43-]2
Place the following in order of increasing entropy at 298 K.

Ne Xe He Ar Kr
d. He<Ne<Ar<Kr<Xe
Identify the process that is endothermic.
d. vaporization
Use Hess's law to calculate ΔG°rxn using the following information.

CO(g) ---> C(s) + 1/2 O2 (g) ΔG°rxn =?

CO (g) ---> C(s) + O2 (g) ΔG°rxn = 394.4 kJ
CO (g) + 1/2 O2(g) ---> CO2 (g) ΔG°rxn = -257.2 kJ
c. 137.2 kJ
Given the following equation.

H2O (g) + CO(g) ----> H2 (g) + CO (g) ΔG°rxn = -28.6 kJ

Calculate ΔG°rxn for the following reaction.

5H2 (g) + 5 CO2 (g) ----> 5H2O (g) + 5 CO (g)
e. 143.0 kJ
Balance the following redox reaction if it occurs in basic solution. What are the coefficients in front of CIO2 and H2O in the balanced reaction?

H2O2 (I) + CIO2 (aq) ---> CIO2- (aq) + O2 (g)
b. CIO2 = 2, H2O = 2
Use the tabulated half-cell potentials to calculate ΔG° for the following balanced redox reaction.

Pb2 (aq) + Cu (s) ---> Pb (s) + Cu 2+(aq)
d. 91 kJ
Identify the location of reduction in an electrochemical cell
e. the cathode
Balance the following redox reaction if it occurs in basic solution. What are the coefficients in front of Cr(OH)4- and CIO in the balanced reaction?

Cr(OH)4- (aq) + CIO- (aq) ---> CrO4^2- (aq) + CI- (aq)
d. Cr(OH)4- = 2, CIO- = 3
The standard emf for the cell using the overall cell reaction below is 0.48 V:

Zn (s) + Ni2+ (aq) ----> Zn2+ (aq) Ni(s)

The emf generated by the cell when [Ni2+] = 2.50 M and [Zn2+] = 0.100 M is _______ v:
c. 0.52
How many electrons are transferred in the following reaction? (The reaction is unbalanced.)

Ni(s) + Cr^3+ (aq) ---> Cr(s) + Ni^2+ (aq)
d. 6
Balance the following redox reaction if it occurs in basic solution. What are the coefficients in front of Cr and CI2 in the balanced reaction?

Cr(s) + CI2(g) ----> Cr^3 (aq) + CI- (aq)
a. Cr = 2, CI2 = 3
Balance the following redox reaction if it occurs in H2SO4. What are the coefficients in front of C10H22O2 and H2SO4 in the balanced reaction?

C10H22O2(aq) + Na2Cr2O7(aq) ----> C10H18O4(aq) + Cr2(SO4)3(aq)
e. C10H2202 = 3, H2SO4 = 16
Which of the following statements is TRUE?
b. If Q = K, it means the reaction is at equilibrium.
Consider the following reaction at equilibrium. What will happen if the volume increased?4

FeS2(s) + 11 O2(g) ⇌ 2 Fe2O3(s) + 8 SO2(g)
d. The equilibrium will change in the direction of the reactants
Determine the value of Kp for the following reaction if the equilibrium concentrations are as follows: P(NOCl)eq = 0.22 atm, P(NO)eq = 0.10 atm, P(Cl2)eq = 0.11 atm.2 NOCl(g) ⇌ 2 NO(g) + Cl2(g)
d. 2.3 × 10-2
An equilibrium mixture of CO, O2 and CO2 at a certain temperature contains 0.0010 M CO2 and 0.0100 M O2. At this temperature, Kc equals 1.4 × 102 for the reaction:

2 CO(g) + O2(g) ⇌ 2 CO2(g).

What is the equilibrium concentration of CO?
d. 8.4 × 10-4 M
Consider the following reaction and its equilibrium constant:

4 CuO(s) + CH4(g) ⇌ CO2(g) + 4 Cu(s) + 2 H2O(g) Kc = 1.10

A reaction mixture contains 0.20 M CH4, 0.70 M CO2 and 1.5 M H2O. Which of the following statements is TRUE concerning this system?
d. The reaction will shift in the direction of reactants
The Brønsted-Lowry model focuses on the transfer of _______ in an acid-base reaction.
e. H+
Which of the following is an Arrhenius acid?
e. H2SO3
Which of the following acids is the weakest? The acid is followed by its Ka value.
a. HCN, 4.9 × 10-10
Calculate the pH for an aqueous hydrobromic acid solution that contains hydronium ion.
e. 2.38
A solution with a hydroxide ion concentration of 4.15 × 10-6 M is ________ and has a hydrogen ion concentration of ________.
a. basic, 2.41 × 10-9 M
Give the expression for Kf for Fe(CN)63-.
[Fe(CN)6^3-]/[Fe^3+] [CN-]6
The difference between Q and Ksp is
c. Ksp is the value of the product at equilibrium and Q is the value of the product under any condition
Calculate the solubility (in g/L) of silver chromate in water at 25°C if the Ksp for Ag2CrO4 is 1.1 × 10-12.
b. 2.2 × 10-2 g/L
A sample contains Ba3(PO4)2, HgS, AgCl, NH4Br, and CoS. Identify the precipitate after the addition of 6 M HCl; then H2S and 0.2 M HCl; and then OH- to a pH of 8.
b. CoS
Identify the compound with the highest ΔG°f.
b. All compounds have a value of zero.
Which of the following statements is TRUE?
c. Endothermic process decrease the entropy of the surroundings, at constant T and P
Identify a process that is NOT reversible.
d. frying an egg
Consider a reaction that has a positive ΔH and a negative ΔS. Which of the following statements is TRUE?
e. This reaction will be nonspontaneous at all temperatures
Phosphorous and chlorine gases combine to produce phosphorous trichloride:

P2(g) + 3 Cl2(g) → 2 PCl3(g)

ΔG° at 298 K for this reaction is -642.9 kJ/mol. The value of ΔG at 298 K for a reaction mixture that consists of and 0.65 atm PCl3 is ________.
b. -649.5
The value of ΔG° at 141.0°C for the formation of phosphorous trichloride from its constituent elements,

P2(g) + 3 Cl2(g) → 2 PCl3(g)

is ________ kJ/mol. At 25.0°C for this reaction, ΔH° is -720.5 kJ/mol, ΔG° is and is
e. -612.3
Determine ΔG°rxn using the following information.

H2(g) + CO(g) → CH2O(g) ΔH°= +1.9 kJ; ΔS°= -109.6 J/K
c. +34.6 kJ
Define a salt bridge.
c. A pathway by which counterions can flow between the half-cells without the solutions in the half-cell totally mixing.
Identify a characteristic that does not describe a standard hydrogen electrode.
d. zinc electrode
The electrolysis of molten AlCl3 for 3.25 hr with an electrical current of 15.0 A produces of aluminum metal.
b. 16.4
Nickel can be plated from aqueous solution according to the following half reaction. How long would it take (in min) to plate 29.6 g of nickel at 4.7 A?

Ni2+(aq) + 2 e⁻ → Ni(s)
b. 3.5 × 102 min
A galvanic cell consists of a Ni2+/Ni half-cell and a standard hydrogen electrode. If the Ni2+/Ni half-cell standard cell functions as the anode, and the standard cell potential is 0.26 V, what is the standard reduction potential for the Ni2+/Ni half-cell?
b. -0.26 V
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