Required
1. Which of the following properties suggest that a reaction is probably at equilibrium? Check all that apply. a) constant macroscopic properties b) unchanging mass c) no change in color for a long period of time d) slow change in electrical conductivity
2. Explain how starting a reaction from either the products side, or the reactants side, can be used as a test for equilibrium.
3. Does reaching equilibrium mean that you will have equal concentrations of reactants and products in the reacting system? a) Yes b) No
4. Which of the following statements about the coefficients in a balanced equation at equilibrium is true? a) They indicate the mole ratio of concentration of reactant and product molecules once equilibrium is reached. b) At equilibrium, the concentration of reactant and product molecules are always equal, no matter what the mole ratio is. c) Their ratio indicates how much of each reactant or product you must start the reaction with. d) The ratio of coefficients indicates the ratio of the way molecules react.
5. What is equal in equilibrium? a) The rate of the forward and reverse reaction b) The concentration of reactants and products c) The ratio in which products and reactants react d) The masses of products and reactants
6. If you started with an empty container, and put in 1 mole of HI (g) and let it react according to this equation:
then when the reaction reached an equilibrium you know that: a) the amount of H2 (g) will equal the amount of I2 (g), and be exactly 1/2 of the amount of HI (g) b) the amount of H2 (g) and I2 (g) together will exactly equal the amount of HI (g). c) whatever the amount of HI reacted, you will get exactly 1/2 that amount of H2 and I2 gases being formed. d) the amounts of all three molecules will be the same, since the reaction is at equilibrium
7. A reaction has been observed and has not changed for a very long time. Which of the following statements is not true? a) The reaction must be at equilibrium since it is not changing. b) For the reaction to be in equilibrium it must be in a closed system. c) If the reaction is at equilibrium, and a radioactive element is added that is part of the reaction, it will end up distributed amongst both reactant and product molecules. d) The reaction may not be at equilibrium. It just may be a very slow reaction.
8. What is meant by a "closed system"? How is a closed system related to the concept of equilibrium?
9. Explain how you can use a radioactive tracer to prove that an equilibrium is dynamic.
10. Consider the following chemical equilibrium:
Which of the following statments is true? a) This reaction cannot be an equilibrium since it combines different states of matter. b) This reaction involves four molecules of reactant, and four molecules of product. At equilibrium there will be equal total amounts of reactants and products, though the individual amount will depend on the coefficient in front of each reaction. c) If this reaction reaches an equilibrium, then carbon dioxide gas and water will not dissolve in each other any longer. d) When equilibrium is achieved there will be just as as fast a reaction between carbon dioxide and water molecules as there is between hydronium and carbonate ions.