_____1. of the Following Reactions, Which Involves the Largest Decrease in Entropy?

Thermodynamics

_____1. Of the following reactions, which involves the largest decrease in entropy?

(A)CaCO3(s) CaO(s) + CO2(g)

(B)2 CO(g) + O2(g) 2 CO2(g)

(C)Pb(NO3)2(s) +2KI(s)PbI2(s) + 2KNO3(s)

(D)C3H8(g) + 5 O2(g) 3 CO2(g) + 4 H2O(g)

(E)4 La(s) + 3 O2(g) 2 La2O3(s)

C2H4(g) + 3 O2(g) 2 CO2(g) + 2 H2O(g)

_____2. For the reaction of ethylene represented above, H is -1,323 kJ. What is the value of H if the combustion produced liquid water H2O(l), rather than water vapor H2O(g) ? (H for the phase change H2O(g) H2O(l) is –44 kJ mol-1.)

(A)-1,235 kJ(B)-1,279 kJ(C)-1,323 kJ

(D)-1,367 kJ(E)-1,411 kJ

_____3. When solid ammonium chloride, NH4Cl(s), is added to water at 25C it dissolves and the temperature of the solution decreases. Which of the following is true for the values of H and S for the dissolving process?

(A)PositivePositive

(B)PositiveNegative

(C)PositiveEqual to zero

(D)NegativePositive

(E)Negative Negative

_____4. For which of the following processes would S have a negative value?

I.2 Fe2O3(s) 4 Fe(s) + 3 O2(g)

II.Mg2+ + 2 OH– Mg(OH)2(s)

III.H2(g) + C2H4(g) C2H6(g)

(A) I only(B) I and II only

(E) I, II, and III

_____5. N2(g) + 3 H2(g) 2 NH3(g)

The reaction indicated above is thermodynamically spontaneous at 298 K, but becomes nonspontaneous at higher temperatures. Which of the following is true at 298 K?

(A)G, H, and S are all positive.

(B)G, H. and S are all negative.

(C)G and H are negative, but S is positive.

(D)G and S are negative, but H is positive.

(E) G and H are positive, but S is negative

_____6. I2(g) + 3 Cl2(g) 2 ICl3(g)

According to the data in the table below, what is the value of Hrxn for the reaction represented above?

Bond / Average Bond Energy (kilojoules/mole)
I–I / 149
Cl–Cl / 239
I–Cl / 208

(A) –860 kJ(B) –382 kJ

(E) +1,248 kJ

_____7. Which of the following reactions has the largest positive value of S per mole of Cl2

a. H2(g) + Cl2(g) 2 HCl(g)

b. C12(g) + 1/2 O2(g) Cl2O(g)

c. Mg(s) + Cl2(g) MgCl2(s)

d. 2 NH4Cl(s) 4 H2(g) + Cl2(g)

e. Cl2(g)2 Cl(g)

_____8. Which of the following must be true for a reaction that proceeds spontaneously from initial standard state conditions?

a. G > 0 and Keq > 1

b. G > 0 and Keq < 1

c.G < 0 and Keq > 1

d. G < 0 and Keq < 1

e. G = 0 and Keq = 1

_____9. H2O(s) H2O(l)

When ice melts at its normal melting point, 273.16 K and 1 atmosphere, which of the following is true for the process shown above?

a. H < 0, S > 0, G > 0

b. H0, S < 0, G > 0

c. H > 0, S < 0, G < 0

d. H > 0, S > 0, G >0

e. H > 0, S > 0, G< 0

_____10. CH4(g) + 2 O2(g) CO2(g) + 2 H2O(l)

Hrxn = –889.1 kJ

Hf H2O(l) = –285.8 kJ/mol

Hf CO2(g) = –393.3 kJ/mol

What is the standard heat of formation of methane,  Hf CH4(g), as calculated from the data above?

(A) –210.0 kJ/mole(D) 75.8 kJ/mole

(B) –107.5 kJ/mole(E) 210.0 kJ/mole

_____11. A cube of ice is added to some hot water in a rigid, insulated container, which is then sealed. There is no heat exchange with the surroundings. What has happened to the total energy and the total entropy when the system reaches equilibrium?

EnergyEntropy

(A)Remains constantRemains constant

(B)Remains constantDecreases

(C)Remains constant Increases

(D)DecreasesIncreases

(E)IncreasesDecreases

_____12. For the reaction A(g) B(g) + C(g), the equilibrium constant, Kp, is 2x10–4 at 25C. A mixture of the three gases at 25C is placed in a reaction flask and the initial pressures are PA= 21 atmosphere, PB= 0.5 atmosphere, and PC= 1 atmosphere. At the instant of mixing, which of the following is true for the reaction as written?

(A) G < 0(C) S = 0(E)  S < 0

(B) G > 0(D) G = 0