Chapter 14, Problem 29P

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

Explain why the development of a vapor pressure above a liquid in a closed container represents an equilibrium. What are the opposing processes? How do we recognize when the system has reached a state of equilibrium?

The following is a thought experiment. Imagine that you put a little water in a test tube and add some NaF crystals. Immediately after you add NaF, you observe that the crystals begin dissolving. The quantity of solid NaF decreases, hut before long, it appears that no more NaF is dissolving. The solution is saturated. The equation for the dissolution of NaF in water is NaF(s) —* Na (aq) + F~(aq). As NaF dissolves, what do you think happens to the rate of dissolution? Describe w hat is occurring on the molecular level. Assume that the reverse reaction, Na+(aq) + F“(aq) —* NaF(s), also occurs as the crystal dissolves. In other words, both dissolution and precipitation are taking place. When it appears that there is no more change in the quantin’ of NaF dissolving (the solution is saturated), w hat has happened to the rates of the forward and reverse reactions? Explain your answer.

Consider a metal ion A2+ and its nitrate salt, In an experiment, 35.00 mL of a 0.217 M solution of A(NO3)2 is made to react with 25.00 mL of 0.195 M NaOH. A precipitate, A(OH)2, forms. Along with the precipitation, the temperature increases from 24.8C to 28.2C. What is H for the precipitation of A(OH)2? The following assumptions can be made. • The density of the solution is 1.00 g/mL. • Volumes are additive. • The specific heat of the solution is 4.18 J/g C.

A chemist wants to prepare phosgene, COCl2, by the following reaction: CO(g)+Cl2(g)COCl2(g) He places 4.00 g of chlorine, Cl2, and an equal molar amount of carbon monoxide, CO, into a 10.00-L reaction vessel at 395C. After the reaction comes to equilibrium, he adds another 4.00 g of chlorine to the vessel in order to push the reaction to the right to get more product. What is the partial pressure of phosgene when the reaction again comes to equilibrium? Kc = 1.23 103.

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?

At a temperature of 60 C, the vapor pressure of water is 0.196 atm. What is the value of the equilibrium constant KP for the transformation at 60 C? H2O(l)H2O(g)

For the system SO3(g)SO2(g)+12 O2(g)at 1000 K, K=0.45. Sulfur trioxide, originally at 1.00 atm pressure, partially dissociates to SO2 and O2 at 1000 K. What is its partial pressure at equilibrium?

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?