Acid & Base Workbook& Problem Set
Read Chapter 2.1 – 2.4 and complete the workbook as you go. Complete the problem set that follows and show all work for full credit. This Workbook and Problem set is due no later than 3AM the night of September 10th (morning of 9/11/12).
Chapter 2.1
Define the term electronegativity and give two examples of electronegative atoms other than oxygen and nitrogen:
Define the term polarity:
Draw a molecule that is polar (other than water) and show the partial positive and negative ends of the molecule as well as the overall direction of the molecular dipole:
Draw a molecule (other than CO2) that has very polar bonds but due to geometry is non-polar overall:
Using KCl draw the interaction of this molecule when it dissolves in water.
What is the relationship between energy, polarity and solubility?
Define Hydrophilic and Hydrophobic and give an example molecule for each.
Define the term amphipathic:
Use a generic fatty acid to draw a micelle. Label the hydrophilic and hydrophobic parts.
If the interaction between hydrophobic molecules is very weak, then why does oil congregate when placed in water?
Chapter 2.2
What three elements can form hydrogen bonds?
Draw a hydrogen bond formation using a molecule made of each of the 3 elements above.
Ice being less dense than water is important for life to exist on Earth. Why?
Hydrogen bonds are common to what kinds of biochemical molecules? Why is this important?
Chapter 2.3
What is an acid?
What is a base?
How do we differentiate a strong acid from a weak acid?
There are only a few common strong acids. Name them:
Draw an acid dissociation reaction for the HF acid:
What does the Ka tell you about and acid and how is this value determined?
Looking at the equation you drew for HF, how does this determine how strong the acid is?
HCl is a strong acid. If you were to calculate the Ka, what value (generally) would you get and why?
Water is not shown in an acid dissociation equation. Why not?
What is the concentration of water in water? Show the calculation of how this value is determined.
What is the value of Kw? Show the calculation of how this value is determined.
Define the term pH:
Define the term pKa:
Write the Henderson-Hasselbalch equation:
Chapter 2.4
What is a titration and why is it used?
Define the term Equivalence point:
What is meant by monoprotic, diprotic and triprotic? Give examples of each.
Why does a titration curve become linearly vertical at the equivalence point? What is happening?
Problem Set:
1. The H-C-H bond angle in the perfectly tetrahedral CH4 molecule is 109o. Explain why the H-O-H bond angle in water is only about 104.5o.
2. Explain why H3O+ is the strongest acid that can exist in a biological system.
3. Calculate the pH of the following:
a. 5.00 x 10-4 M HCl
b. 7.00 x 10-5 M NaOH
c. 2 mM HCl
d. 3 x 10-2 M KOH
e. 0.04 mM HCl
f. 6 x 10-9 M HCl
4. Calculate the [H+] of the following:
a. Vinegar pH = 2.9
b. Saliva pH = 6.6
c. Household Ammonia pH = 11.4
d. Inside a liver cell pH = 6.9
5. Calculate the [OH-] of the following:
a. Milk of Magnesia pH = 10.3
b. Beer pH = 4.5
6. The pH of a 0.02 M solution of an acid was measured at 4.6.
a. What is the [H+] in this solution?
b. Calculate the acid dissociation constant Ka and pKa for this acid.