2. Look at the following reaction: N₂O (g) 2NO2 (g) + 32.1 kJ 3. 4. What would you have to do to the reaction in order to increase the magnitude of K? If Q

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?

Methanol, a common laboratory solvent, poses a threat of blindness or death if consumed in sufficient amounts. Once in the body, the substance is oxidized to produce formaldehyde (embalming fluid) and eventually formic acid. Both of these substances are also toxic in varying levels. The equilibrium between methanol and formaldehyde can be described as follows: CH3OH(aq)H2CO(aq)+H2(aq) Assuming the value of K for this reaction is 3.7 1010, what are the equilibrium concentrations of each species if you start with a 1.24 M solution of methanol? What will happen to the concentration of methanol as the formaldehyde is further converted to formic acid?

Because carbonic acid undergoes a second ionization, the student in Exercise 12.39 is concerned that the hydrogen ion concentration she calculated is not correct. She looks up the equilibrium constant for the reaction HCO,-(aq) «=* H+(aq) + COf'(aq) Upon finding that the equilibrium constant for this reaction is 4.8 X 10“H, she decides that her answer in Exercise 12.39 is correct. Explain her reasoning. A student is simulating the carbonic acid—hydrogen carbonate equilibrium in a lake: H,CO,(aq) 5=6 H+(aq) + HCO,'(aq) K = 4.4 X 10'7She starts with 0.1000 A1 carbonic acid. W hat are the concentrations of all species at equilibrium?

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.

In the figure, orange fish are placed in one aquarium and green fish in an adjoining aquarium. The two tanks are separated by a removable partition that is initially closed. (a) Describe what happens in the first few minutes after the partition is opened. (b) What would you expect to see several hours later? (c) How is this system analogous to dynamic chemical equilibrium?

The equilibrium constant expression for a given reaction depends on how the equilibrium equation is written. Explain the meaning of that statement. You may, if you wish, use the equilibrium equation N2(g)+3H2(g)2NH3(g) to illustrate your explanation.

During an experiment with the Haber process, a researcher put 1 mol N2 and 1 mol H2 into a reaction vessel to observe the equilibrium formation of ammonia, NH3. N2(g)+3H2(g)2NH3(g) When these reactants come to equilibrium, assume that x mol H2 react. How many moles of ammonia form?

Chemical Equilibrium II Magnesium hydroxide. Mg(OH)2, is a white, partially soluble solid that is used in many antacids. The chemical equation for the dissolving of Mg(OH)2(s) in water is Mg(OH)2(s)Mg2+(aq)+2OH(aq) a Describe a simple experimental procedure that you could use to study this solubility equilibrium. In your experiment, how would you determine when the solution process has attained equilibrium? b Write the equilibrium-constant expression for this dissolving of magnesium hydroxide. c Suppose equilibrium has been established in a container of magnesium hydroxide in water, and you decide to add more solid Mg(OH)2. What would you expect to observe? What effect will this addition of Mg(OH)2 have on the concentrations of Mg2+(aq) and OH(aq)? d Say you haw prepared an equilibrium solution of Mg(OH)2 by adding pure solid Mg(OH)2 to water. If you know the concentration of OH(aq), can you determine the concentration of Mg2+(aq)? If not, what information do you need that will allow you to determine the answer? e You slowly add OH from another source (say, NaOH) to an equilibrium mixture of Mg(OH)2 and water. How do you expect the concentration of the Mg2+(aq) to change? What might you be able to observe happening to the Mg(OH)2(s) as you add the OH? f Next you remove some, but not all, of the Mg(OH)2(s) from the mixture. How will this affect the concentrations of the Mg2+(aq) and OH(aq)? g If someone hands you a container of Mg(OH)2(aq) and there is no solid Mg(OH)2 present, is this solution at equilibrium? If it is not at equilibrium, what could you add to or remove from the container that would give an equilibrium system? h Consider an individual OH(aq) ion in an Mg(OH)2 solution at equilibrium. If you could follow this ion over a long period of time, would you expect it always to remain as an OH(aq) ion, or could it change in some way?

12.85 In the figure, orange fish are placed in one aquarium and green fish in an adjoining aquarium. The two tanks are separated by a removable partition that is initially closed. Describe what happens in the first few minutes after the partition is opened. WTiat would you expect to see several hours later? How is this system analogous to dynamic chemical equilibrium?