1. Write the equilibrium constant expression for the following reaction:

          _{K =} ^{_______________}

If the value of K for this reaction is 1.3 x 10⁸ at a particular temperature, in which direction does the

equilibrium lie mainly? _____________left or right? Would you expect to find a higher concentration

of product or reactants in the equilibrium mixture at this temperature?______________
 

2. Consider the following reaction:

a.) Write the word “heat” in the above equation as either a product or a reactant,

based on the enthalpy, delta H, of the reaction.

b.) Which direction would the reaction shift if the temperature was increased?______________

Wouild this shift increase the concentration of the products or reactants?____________

c.) What effect (increase K, decrease K, or no effect) would this shift have on the

value of K for this reaction after equilibrium was reestablished?______________

d.) Which direction would the reaction shift if the pressure inside the reaction vessel was

increased?______________

e.) If more CH₄ was added to the system at equilibrium what direction would the reaction shift?___________

f.) Would this increase or decrease the CO concentration?__________

The H₂O concentration?_____________
 

3. a.) Would a reaction with a positive delta H and a negative delta S be spontaneous or not? _________

b.) Does the entropy of water decrease or increase when it freezes?___________

when it boils?___________

c.) If thedelta G for a reaction is -278 kcal will the reaction be spontaneous or not? _____________
 
 

4. The following apply to the forward reaction for the diagram below - label all arrows, etc.

a.) On the diagram, label reactants, products, activated complex(es). Using the arrows on the diagram label the catalyzed and uncatalyzed potential energy curves.

b.) On the Potential Energy axis indicate the energy of the reactants, the energy of the products, and the energy of the activated complex(es)
.
c.) Draw arrows on the diagram to indicate the activation energies, E_a, for both the catalyzed and uncatalyzed reactions and another arrow to indicate delta H, the net energy of reaction.

d.) Is the reaction exothermic or endothermic?____________________

e.) Why does a catalyst increase the rate of a reaction? Explain by referring to your diagram.
 

5. Give the definition for a Bronsted acid.
 

For the following forward reaction, underline the acid and its conjugate base and circle the base and its conjugate acid.

6. What is the pH of a solution with a [H₃O⁺] = 3.5 x 10^-4 ?____________

7. K_w = [H₃O⁺] [OH^-]. What is the numerical value of K_w? ___________What is the [OH^-] in a solution

that has a [H⁺] of 1 x 10^{- 9} ?_________________Is this solution acidicor basic?____________

8. Underline the acid(s) which ionize100% in water: HF HCl HNO₃ HC₂H₃O₂ HCN H₂SO₄

9. Write the equation for the ionization of ammonia, NH₃, in water.
Does NH₃ ionize 100% in water?___________ Is NH₃ a strong or weak base?________
 

10. A student performed a titration in lab. She pipetted 10.00 ml of H₂SO₄ into a flask and added 2 drops of phenophthalein indicator. She filled the buret with 0.100 M NaOH and began adding base slowly from the buret until the solution in the flask turned a pale pink and stayed pink, indicating that all of the acid in the flask had been neutralized and the titration was finished. At this point 15.65 mL of NaOH had been added from the buret. Show all calculations below.

a.) Write a balanced equation for the neutralization reaction that occured during this titration:
 
 

b.) How many moles of NaOH were added from the buret?____________moles
 
 
 

c.) Use your answer from b. and the balanced equation in a. to determine how many moles of H₂SO₄
were in the flask.
____________moles

d.) Calculate the molarity of the H₂SO₄, using the equation M = ^________ (complete the equation)
 
 
 
 

11. Which of the following is the strongest acid?___________
                          acid                K_a
                        H₂CO₃         4.3 x 10^-7
                        H₂PO₄^-         6.2 x 10^-8
                        CH₃COOH     1.8 x 10^-5

12. A solution of the following “generic” weak acid, HA, and its conjugate base, A^-, make up a buffer.
If a few drops of HCl or NaOH are added to this solution the pH will not change very much. Write two
chemical reactions showing how each will react with one of the two components of thebuffer.