Things to know:
1. Explain DYNAMIC EQUILIBRIUM. Why does a reaction at equilibrium look like it is NOT reacting? 2. Are all reactions equilibrium reactions? What assumptions do we make when we say that a reaction does NOT take place or that it is UNIDIRECTIONAL and goes 100% to completion 3. Be able to sketch a graph of the following (assuming that you start with all reactants and no products) : a. A reaction that really doesn’t do anything
b. A reaction that seems to go to completion (Unidirectional) c. A reaction that favours the forward direction of the reaction d. A reaction that seems to have an equal balance of reactants and products at equilibrium e. A reaction that favours the reverse direction of the reaction 4. What does a K value represent for an equilibrium reaction? Write the generic equation for K 5. Match the following K values to the graphs that you created in question 3: a. Keq = very large
b. Keq = 1.0 (approx.)
c. Keq = 5.0 x 10-12
d. Keq = 3.5 x 102
e. Keq = very small
6. Outline Le Chatalier’s principles of equilibrium with respect to addition or removal of reactants and products, change in temperature for exo and endothermic reactions, and change in pressure where gases are involved in the reaction. 7. Why does the addition of a catalyst not alter the equilibrium? What does it do? 8. Does the addition of spectator ions or inert gases alter the equilibrium? 9. Be able to write the Keq expression for an equilibrium reaction. REMEMBER: the coefficients from the balanced equation become the exponents! 10. Be able to construct an ICE table to find equilibrium concentrations! 11. Given a Keq expression, be able to write the balanced equation! 12. Be able to match the column with definitions for the following terms: a. Keq, Ka, Kb
b. Acid, Base
d. Weak acid, weak Base
e. pH, pOH
f. Strong Acid, Strong Base
g. Buffer solution
13. Be able to write out the equilibrium that takes place in a simple beaker of water. What is the Kw expression? pKw = 14! Why is this really helpful? 14. Be able to draw a diagram of hydronium ion. Why does this structure form spontaneously? 15. Be able to label Acid, Base, Conjugate Acid, Conjugate Base for an acid/base equilibrium 16. Be able to convert from pH/ H3O+ to pOH/ OH- for a strong acid or base 17. Be able to find pH for a weak acid using an ICE table and the Ka equation (and Ka value) 18. Be able to find pH (or pOH) for a weak base using ICE table and the Kb equation (and Kb value) 19. Be able to convert from pH/ H3O+ to pOH/ OH- for a weak acid or base 20. Be able to COMPARE relative pH values for acids or bases with the SAME concentration but differing Ka or Kb values 21. What is a buffer? How do buffers work? Be able to PLUG-and –SOLVE for a simple buffer question!
Sample Questions: See assigned homework questions for this unit, plus hand-outs and power points available on the classes web page!
Review session TUESDAY at lunch next week!