Suppose a reaction has the equilibrium constant K = 1.3 108. What does the magnitude of this constant tell you about the relative concentrations of products and reactants that will be present once equilibrium is reached? Is this reaction likely to be a good source of the products?

Kc at 137 C is 4.42 for NO(g) + 12 Br2(g) NOBr(g) Calculate Kc at 137 C for 2NOBr(g) 2NO(g) + Br2(g)

The decomposition of PCl5(g) to form PCl3(g) and Cl2(g) has Kc = 33.3 at a high temperature. If the initial concentration of PCl5 is 0.1000 M, what are the equilibrium concentrations of the reactants and products?

What is Le Chteliers principle? Consider the reaction 2NOCI(g)2NO(g)+Cl2(g) If this reaction is at equilibrium. what happens when the following changes occur? a. NOCI(g) is added. b. NO(g) is added. c. NOCI(g) is removed. d. Cl2(g) is removed. e. The container volume is decreased. For each of these changes, what happens to the value of K for the reaction as equilibrium is reached again? Give an example of a reaction for which the addition or removal of one of the reactants or products has no effect on the equilibrium position. In general, how will the equilibrium position of a gas-phase reaction be affected if the volume of the reaction vessel changes? Are there reactions that will not have their equilibria shifted by a change in volume? Explain. Why does changing the pressure in a rigid container by adding an inert gas not shift the equilibrium position for a gas-phase reaction?

What is the law of mass action? Is it true that the value of K depends on the amounts of reactants and products mixed together initially? Explain. Is it true that reactions with large equilibrium constant values are very fast? Explain. There is only one value of the equilibrium constant for a particular system at a particular temperature, but there is an infinite number of equilibrium positions. Explain.

At room temperature, the equilibrium constant Kc for the reaction 2 NO(g) ⇌ N2(g) + O2(g) is 1.4 × 1030. Is this reaction product-favored or reactant-favored? Explain your answer. In the atmosphere at room temperature the concentration of N2 is 0.33 mol/L, and the concentration of O2 is about 25% of that value. Calculate the equilibrium concentration of NO in the atmosphere produced by the reaction of N2 and O2. How does this affect your answer to Question 11?

At 77 C, Kp is 1.7 104 for the formation of phosphorus pentachloride from phosphorus trichloride and chlorine. PCl3(g) + Cl2(g) PCl5(g) Calculate Kp for PCl5(g) PCl3(g) + Cl2(g)

Because calcium carbonate is a sink for CO32- in a lake, the student in Exercise 12.39 decides to go a step further and examine the equilibrium between carbonate ion and CaCOj. The reaction is Ca2+(aq) + COj2_(aq) ** CaCO,(s) The equilibrium constant for this reaction is 2.1 X 10*. If the initial calcium ion concentration is 0.02 AI and the carbonate concentration is 0.03 AI, what are the equilibrium concentrations of the ions? A student is simulating the carbonic acid—hydrogen carbonate equilibrium in a lake: H2COj(aq) H+(aq) + HCO}‘(aq) K = 4.4 X 10"7 She starts with 0.1000 AI carbonic acid. What are the concentrations of all species at equilibrium?

Carbon tetrachloride can be produced by the following reaction: CS2(g) + 3 Cl2(g) S2Cl2(g) + CCl4(g) Suppose 0.12 mol of CS2 and 0.36 mol of Cl2 are placed in a 10.0-L flask. After equilibrium has been achieved, the mixture contains 0.090 mol CCl4. Calculate Kc.