At 25 °C, the reaction 2NH3(g) N2(g) + 3H2(g) has Kc = 2.3 x 10-9. If 0.021 mol NH3 is placed in a 3.38 L container, what will the concentrations of N2 and H2 be when equilibrium is established? Make simplifying assumptions in your calculations. Assume the change in NH3 concentration is insignificant if compared to initial value.

Write a chemical equation for an equilibrium system that would lead to the following expressions (ad) for K. (a) K=(PH2S)2 (PO2)3(PSO2)2 (PH2O)2 (b) K=(PF2)1/2 (PI2)1/2PIF (c) K=[ Cl ]2(Pcl2)[ Br ]2 (d) K=(PNO)2 (PH2O)4 [ Cu2+ ]3[ NO3 ]2 [ H+ ]8

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?

For the reactionH2(g)+I2(g)2HI(g), consider two possibilities: (a) you mix 0.5 mole of each reactant. allow the system to come to equilibrium, and then add another mole of H2 and allow the system to reach equilibrium again. or (b) you mix 1.5 moles of H2 and 0.5 mole of I2 and allow the system to reach equilibrium. Will the final equilibrium mixture be different for the two procedures? Explain.

. What does it mean to say that a state of chemical or physical equilibrium is dynamic?

Consider 0.200 mol phosphorus pentachloride sealed in a 2.0-L container at 620 K. The equilibrium constant, Kc, is 0.60 for PCl5(g) PCl3(g) + Cl2(g) Calculate the concentrations of all species after equilibrium has been reached.

Write equilibrium constant expressions for the following generalized reactions. a. 2X(g)+3Y(g)2Z(g) b. 2X(g)+3Y(s)2Z(g) c. 2X(s)+3Y(s)2Z(g) d. 2X(g)+3Y(g)2Z(s)

Explain that equilibrium is dynamic, and that at equilibrium the forward and backward reaction rates are equal.

In a solution with carbon tetrachloride as the solvent, the compound VCl4. undergoes dimerization: 2VCl4V2Cl8 When 6.6834 g VCl4. is dissolved in 100.0 g carbon tetrachloride, the freezing point is lowered by 5.97C. Calculate the value of the equilibrium constant for the dimerization of VCl4 at this temperature. (The density of the equilibrium mixture is 1.696 g/cm3, and Kf = 29.8C kg/mol for CCl4.)

Show that the complete chemical equation, the total ionic equation, and the net ionic equation for the reaction represented by the equation KI(aq)+I2(aq)KI3(aq) give the same expression for the reaction quotient. KI3 is composed of the ions K+ and I3-.