6. Thermodynamics and Kinetics

For each of the following processes, indicate whether you expect ∆S° to be greater than, less than, or equal to 0. Explain your answer.

(c)

For each of the following processes, indicate whether you expect ∆S° to be greater than, less than, or equal to 0. Explain your answer.

(b) 2 C₆H₁₄(l) + 19 O₂(g) → 12 CO₂(g) + 14 H₂O(g)

Using the bond-dissociation energies in Table 5.6 (see Section 5.3.1), estimate the equilibrium constant of the following reaction at 298 K.

For the following reactions we have not seen yet, which side, if either, would be favored by increasing the temperature?

(b)

Predict which side of the equilibrium is favored by ∆H, ∆G, and ∆S.

For each of the following processes, indicate whether you expect ∆S° to be greater than, less than, or equal to 0. Explain your answer.

(a) Boiling water

In Chapter 13, we discuss the ring-opening reactions of epoxides, such as the one shown here.

(b) Predict the sign of ∆S°.

Would you expect ∆S to be greater than, less than, or equal to zero in the following reactions?

a.

For a reaction carried out at 25 °C with an equilibrium constant of 1 × 10^-3, to increase the equilibrium constant by a factor of 10:

a. how much must ∆G° change?

b. how much must ∆H° change if ∆S° = 0 kcal mol^-1 K^-1?

c. how much must ∆S° change if ∆H° = 0 kcal mol^-1?

From the following rate constants, determined at five temperatures, calculate the experimental energy of activation and ∆G^‡, ∆H^‡, and ∆S^‡ for the reaction at 30 °C:

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a. What is the equilibrium constant for a reaction that is carried out at 25 °C (298 K) with ∆H° = 20 kcal/mol and ∆S° = 5.0 × 10^-2 kcal mol^-1 K^-1?

b. What is the equilibrium constant for the same reaction carried out at 125 °C?

(ii) Which side of the reaction is favored by entropy? (iii) If ∆S° = 0 for these reactions, calculate ∆G° (Assume T = 298 K) [BDE for O―H = 110 kcal /mol.]

(b)

For the following values of ∆H° , ∆S°, and T, tell whether the process would be favored.

(b) ∆H° = +7.34 kcal/mol ; ∆S° = +43 cal/mol•K ; T = 325 K

Considering the process described in Assessment 5.13, will it be favored or disfavored at a temperature higher than the one you calculated? How about at a temperature below what you calculated?

For the following values of ∆H° , ∆S°, and T, tell whether the process would be favored.

(d) ∆H° = -8.3 kcal/mol ; ∆S° = -12 cal/mol•K ; T = 298 K