Mar 23, 2015 - Salt dissolves in H2O. b. A clear solution becomes a uniform color after a few drops of dye are added. c. Iron rusts. d. You clean your...
AP CHEM HOMEWORK 3-23-2015 Read: 749-759 1. What does it mean to say that a reaction or process is spontaneous? 2. How are thermodynamics and kinetics different? 3. What is entropy? 4. Give an example of an increase in entropy. 5. Which of the following processes are spontaneous? a. Salt dissolves in H2O. b. A clear solution becomes a uniform color after a few drops of dye are added. c. Iron rusts. d. You clean your bedroom. 6. Which of the following processes are spontaneous? a. A house is built. b. A satellite is launched into orbit. c. A satellite falls back to earth. d. The kitchen gets cluttered. 7. Describe what is meant by the following statement: “Entropy is a thermodynamic function that describes the number of arrangements (positions and/or energy levels) that are available to a system existing in a given state.” 8. Which of the following involve an increase in the entropy of the system? a. melting of a solid b. sublimation c. freezing d. mixing e. separation f. boiling 9. Predict the sign of Ssurr for the following processes. a. H2O(l) →H2O(g) b. CO2(g) → CO2(s) 10. Calculate Ssurr for the following reactions at and 1 atm. a. C3H8(g) + 5O2(g) → 3CO2(g) + 4H2O(l) b. 2NO2(g) → 2NO(g) + O2(g)
H° = -2221 kJ H° = 112 kJ
11. Describe the first and second law of thermodynamics. 12. The synthesis of glucose directly from CO2 and H2O and the synthesis of proteins directly from amino acids are both nonspontaneous processes under standard conditions. Yet it is necessary for these to occur for life to exist. In light of the second law of thermodynamics, how can life exist?
13. The equation describes the relationship between enthalpy, temperature and entropy. Answer the following questions related to the equation.
a) Why is the equation negative? b) Explain the following and relate to the equation above, “Life itself is a decrease in entropy.” c) Explain why an exothermic reaction causes an increase in entropy to the surroundings. 14. At what temperatures will the following be spontaneous? a) b) c) d)
H = -18kJ and S = -60.J/K H = +18kJ and S = +60.J/K H = +18kJ and S = -60.J/K H = -18kJ and S = +60.J/K