BioChem 210 Module 2 Exam - Portage Learning

1.  The pH of a solution of 0.0010 M NaOH is

2.  Water is a unique molecule. Which of the following contributes to water's unique place in the chemical world?

3.  The bent shape of water is due to ______________.

4.  Which diagrams correctly represent a hydrogen bond?:

5.  The H+ concentration of a solution is 1.2 x 10-3 M. What is the pH?

6.  If the Ka of an acid is 5.63 x 10-3, what is the pKa?

7.  List the acids in DECREASING order of strength (strongest to weakest): 

Nitrous acid (Ka = 4.0 x 10-4); acetic acid (Ka = 1.7 x 10-5); phosphoric acid 

(Ka = 7.3 x 10-3):

8.  Elemental iodine (I2) is a solid at room temperature. What is the dominant attractive force that exists between I2 molecules in the solid?

9.   9. Which one of the following molecules can form a hydrogen bond? (A.) HBr 

(B.) HCl (C.) NH3 (D.) CH4 (E.) H2:  

10.  A hydrogen bond can form between a hydrogen atom bonded to oxygen, 

O-H, and ________.

11.  In a bond between P and Cl, there exists a difference in electronegativity resulting in partial positive and partial negative charges. If a dipole arrow were added to this structure, which way would the arrow point?

12.  The following reaction occurs in glues purchased from hardware stores. 

Customers use this product to glue plastic together. Epoxy

(l) + hardener (l) ö 

Glue (s) + heat given off What is the sign (+ or -) of the change in ” G and ” H?

13.  Which of the following is the free-energy change of a reaction?

14.  Which of the following is the change in entropy of a

reaction?

15.   

16.  Which buffer system is used by the renal system to maintain pH balance?-

17.  A buffer can neutralize acid and base within a certain limit.

We say that this is its

18.  Is a pH of 8.36 acidic, neutral, or basic?

19.  The "ion product" is equal to what value?

20.  In equilibrium constant expressions, the concentration is expressed in units of _______ as indicated the by the brackets [ ].

21.  A pH = 5.0 indicates a concentration of OH- (in M) of __________.

22.   The lysosome has a pH of 5.0. Which of the following weak acids would best work to buffer at pH

5.0?

23.  Which of the following compounds would not be soluble in water?

24.  The oxygen in water has what type of hybridization?

25.  Four identical molecules dissolve in water. Each molecule contains both a polar portion and nonpolar portion of structure. The four molecules interact in such a way that the nonpolar sections align. This is an example of the 

_________

26.  (Short Response) How does the strength of a hydrogen bond compare to the strength the London Force? Also, how about the strength of a hydrogen bond compare to a dipole-dipole force? Briefly comment on these differences.

27.  (Short Response) The weak acid HX has the following equilibrium reaction with 0.64M HX, 0.55M X-, and 0.55M H+. Calculate the Ka for this hypothetic compound. Show your work. HX = H+ + X

28.  (Short Response) Use the general ionization equation for a weak acid to show how a buffer resists changes to the addition of Acid (H+). HA = A- + H+:

29.           (Fill in the blanks) At cool temperatures, water vapor turns into liquid water releasing heat in the process. Fill in the missing blanks, below, regarding this process. Please identify your answers by writing "A." then your answer, "B" then your answer, and so forth. "The free-energy change, ” G, has a _____A______ value (choose "+" or "-"). The enthalpy change, __B__ (fill in symbol), has a ___C_____ value (choose "+" or "-"). The _____D______change, (” S) has a ______E_____ value (choose "+" or "-").": -

30.  (Short Response) What is the hydrophobic effect and how does a clathrate help explain this phenomenon?