Since G RTlnK at equilibrium where G0 ln K 0 K 1 AP Example 1993 2 C 4 H 10 g

Since g rtlnk at equilibrium where g0 ln k 0 k 1 ap

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Since G = -RTlnK, at equilibrium where G=0, ln K = 0, K = 1.
AP Example - 1993 2 C 4 H 10 ( g ) + 13 O 2 ( g )  8 CO 2 ( g ) + 10 H 2 O( l ) The reaction represented above is spontaneous at 25°C. Assume that all reactants and products are in their standard state. a. Predict the sign of Δ S ° for the reaction and justify your prediction. b. What is the sign of Δ G ° for the reaction? How would the sign and magnitude of Δ G ° be affected by an increase in temperature to 50°C? Explain your answer. c. What must be the sign of Δ H ° for the reaction at 25°C? How does the total bond energy of the reactants compare to that of the products? d. When the reactants are place together in a container, no change is observed even though the reaction is known to be spontaneous. Explain this observation.
AP Example - 1993 2 C 4 H 10 ( g ) + 13 O 2 ( g )  8 CO 2 ( g ) + 10 H 2 O( l ) The reaction represented above is spontaneous at 25°C. Assume that all reactants and products are in their standard state. a. Predict the sign of Δ S ° for the reaction and justify your prediction. b. What is the sign of Δ G ° for the reaction? How would the sign and magnitude of Δ G ° be affected by an increase in temperature to 50°C? Explain your answer. a) S < 0 ; more gas particles in the reactants, therefore there is less entropy in the products b) G < 0 since it is spontaneous at the given temperature. Raising the temperature to 50 o C will make G less negative (since S<0).
AP Example - 1993 2 C 4 H 10 ( g ) + 13 O 2 ( g )  8 CO 2 ( g ) + 10 H 2 O( l ) The reaction represented above is spontaneous at 25°C. Assume that all reactants and products are in their standard state. c. What must be the sign of Δ H ° for the reaction at 25°C? How does the total bond energy of the reactants compare to that of the products? d. When the reactants are place together in a container, no change is observed even though the reaction is known to be spontaneous. Explain this observation. c. H is negative; bond energy of the reactants at greater than the products. d. A catalyst is needed since the energy of activation is high.
Homework – DUE Tuesday, April 9th 1. Find the free energy of formation for the oxidation of water to produce hydrogen peroxide: 2 H 2 O(l) + O 2 (g)  2 H 2 O 2 (l) Given the following standard free energy values (ΔG o ) H 2 O(l) = 56.7 kcal/mol O 2 (g) = 0 kcal/mol H 2 O 2 (l) = -27.2 kcal/mol 2. Consider the reaction: 2SO 2 (g) + O 2 (g) 2SO 3 (g) carried out at 25°C and 1 atm. Calculate ∆H°, ∆S°, and ∆G° using the following data: Substance S o (J K -1 mole -1 ) SO 2 (g) -297 248 SO 3 (g) -396 257 O 2 (g) 0 205
Homework – DUE Tuesday, April 9th 3. Using the following data (at 25°C) C diamond (s)+O 2 (g)→CO 2 (g) ∆G°= -397 kJ (16.5) C graphite (s)+O 2 (g)→ CO 2 (g) ∆G°= -394 kJ (16.6) Calculate ∆G° for the reaction: C diamond (s)→C graphite (s) 4. One method for synthesizing methanol (CH 3 OH) involves reacting carbon monoxide and hydrogen gases: CO(g)+2H 2 (g)→CH 3 OH(l) Calculate ∆G at 25°C for this reaction where carbon monoxide gas at 5.0 atm and hydrogen gas at 3.0 atm are converted to liquid methanol.

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• Fall '19