部 23 K=2 At equilibrium? K At equilibrium? ○ yes O no ○ yes ○ no ○ yes O no ○ yes O no K=1 At equilibrium? K=1 At equilibrium? Tiny samples of aqueous solutions are sketched below, as if under a microscope so powerful that individual molecules could be seen. (The water molecules are not shown.) The two substances in each sample can interconvert. That is, each kind of molecule can turn into the other. The equilibrium constant K for each interconversion equilibrium is shown below the sketch. Decide whether each solution is at equilibrium.

In Section 13.1 of your text, it is mentioned that equilibrium is reached in a closed system. What is meant by the term closed system. and why is it necessary to have a closed system in order for a system to reach equilibrium? Explain why equilibrium is not reached in an open system.

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?

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

Describe a nonchemical system that is in equilibrium, and explain how the principles of equilibrium apply to the system.

12.101 An engineer working on a design to extract petroleum from a deep thermal reservoir wishes to capture toxic hydrogen sulfide gases present by reaction with aqueous iron(II) nitrate to form solid iron(II) sulfide. (a) Write the chemical equation for this process, assuming that it reaches equilibrium. (b) What is the equilibrium constant expression for this system? (c) How can the process be manipulated so that it does not reach equilibrium, allowing the continuous removal of hydrogen sulfide?

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)

In Section 17.3 of your text, it is mentioned that equilibrium is reached in a closed system. What is meant by the term “closed system,” and why is it necessary for a system to reach equilibrium? Explain why equilibrium is not reached in an open system.

A solution is prepared by dissolving 0.050 mol of diiodocyclohexane, C5H10I2, in the solvent CCl4.The total solution volume is 1.00 L When the reaction C6H10I2 C6H10 + I2 has come to equilibrium at 35 C, the concentration of I2 is 0.035 mol/L. (a) What are the concentrations of C6H10I2 and C6H10 at equilibrium? (b) Calculate Kc, the equilibrium constant.

5.2. What is the difference between a static equilibrium and a dynamic equilibrium? Give examples difference from the examples in the text. What is similar for the two types of equilibria?