The standard free energy of formation of nitric oxide, NO, at 1000.K (roughly the temperature in an automobile engine during ignition)is 77.7 kJ/mol. Calculate the equilibrium constant for the reaction N2 (g) + O2 (g) 2NO(g) At 1000.K.(R = 8.31 J/(K ∙ mol))

A)0.95

B)7.6 × 10-9

C)1.6 × 105

D)-15

E)8.7 × 10-5

Which of the following statements is true concerning the electrochemical cell depicted below? Zn | Zn2+(aq) || Cu2+(aq) | Cu?

Zn2+(aq) + 2e− Zn(s); E° = -2.87 V

Cu2+(aq) + 2e− Cu(s); E° = -2.38 V

a. The cell reaction is spontaneous with a standard cell potential of 0.49 V

b. The cell reaction is nonspontaneous with a standard cell potential of -0.49 V

c. The cell is at equilibrium

d. The cell reaction is spontaneous with a standard cell potential of 5.25 V

e. The cell reaction is nonspontaneous with a standard cell potential of -5.25 V

Based on the following data, what is the standard Gibbs free energy of formation of the sulfate ion at 298 K? ( R = 8.31 J/(K ∙ mol))

PbSO4(s) Pb2+(aq) + SO42-(aq); Ksp = 1.7 × 10-8

Substance ΔG°f (kJ/mol) at 298 K

Pb2+(aq)

-24.4

PbSO4(s)

-813.0

a. -788.6 kJ/mol

b. -793.1 kJ/mol

c. -837.4 kJ/mol

d. -744.3 kJ/mol

e. 832.9 kJ/mol

The cell potential of the following cell is determined using an unspecified concentration of acid. What is [H +] given that the measured cell potential is -0.464 V and the anode reduction potential ( E °) is 0.222 V at 25 °C?



Ag(s) | AgCl(s) | Cl−(1.0 M) || H+(aq, ? M) | H2(g, 1.0 atm) | Pt(s)

a. 9 x 10^-3 M

b. 9.3 x 10^-4 M

c. 2.6 x 10^-12 M

d. 6.7 x 10^-9 M

e. 8.2 x 10^-6 M

18. If the cell is initially at standard-state conditions, which of the following statements is true?

Zn2+(aq) + 2e- ↔Zn(s); E° = -0.76 V

Cu2+(aq) + 2e- ↔Cu(s); E° = 0.34 V

A. Initially Kc = 2 x 10-37, and it decreases with time.

B. Initially Kc = 2 x 1037, and it does not change with time.

C. Initially Kc = 2 x 1037, and it decreases with time.

D. Initially Kc = 2 x 1037, and it increases with time.

E. Initially Kc = 2 x 10-37, and it increases with time.

Which of the following is correct for the condensation of gaseous ammonia at -38°C? The normal boiling point of ammonia is -33°C.

a. DH 0, DS > 0, and DG > 0

c. DH 0, and DG 0, DS 0

What is the change in internal energy ( ΔU ) of the system if q = -8 kJ and w = -1 kJ for a certain process?

a. -7 kJ

b. 9 kJ

c. 7 kJ

d. -9 kJ

e. -8 kJ

When an aqueous solution of sodium sulfate is electrolyzed, what are the expected products?

Reduction Half-Reaction

E° (V)

Na+(aq) + e¯ Na(s)

-2.71

2H2O(l) + 2e- H2(g) + 2OH-(aq)

-0.83

2H+(aq) + 2e- H2(g)

0.00

O2(g) + 4H+(aq) + 4e- 2H2O(l)

1.23

S2O82-(aq) + 2e- 2SO42-(aq)

2.01

a. H2 (g), OH^- (aq), O2 (g), and H^+ (aq)

b. O2 (g), H^+ (aq), and Na (s)

c. H2 (g), OH^- (aq), and Na (s)

d. H2 (g), OH^- (aq), and S2O8^2- (aq)

e. Na (s) and H2 (g)