Standard Exercises

1. Make a plot of pH vs. log(C_HA) for acetic acid.
   1. What is the slope of the line at high concentration? Explain, based on the equilibrium equations, why this slope is obtained.
   2. What is the slope of the line at low concentration? Explain.
   3. At what concentration does acetic acid undergo a transition between these two limiting behaviors? Explain, based on the equilibrium expressions, and explain what is happening chemically that distinguishes these regions.
   4. Does acetic acid ever behave like a "strong" acid? Explain why or why not.
   
   
2. Make a plot of pH vs. log(C_HA) for hydrofluoric acid(HF). Compare your result with that obtained in (1). Is there an intermediate behavior? Explain.
   1. Under what conditions does HF behave like a "weak" acid? Explain
   2. Under what conditions does HF behave like a "strong" acid? Explain
   3. Under what conditions does a solution of HF behave like pure water?

1. Open the Virtual Titrator
2. Choose a relatively strong monoprotic weak acid (1e-5 < ka < 1)
   • Choose the <Acid> menu from the menu bar of the main window
   • Next, choose the submenu <Monoprotic>
   • Finally, choose the acid of your choice from the list
   • These are some good examples:
     • Chloroacetic Acid
     • Chlorous Acid
     • Iodic Acid
     • Pyruvic Acid
3. Switch to a graph of pH vs. log(Acid Concentration)
   • Choose the <Graphs> menu from the menu bar of the main window
   • Then, choose the graph named: pH vs. log Acid Concentration
4. Figure out the regions of this graph that correspond to each of the approximations

1. Open the Virtual Titrator
2. Choose a very weak monoprotic weak acid (ka < 1e-7)
3. These are some good examples:
   • Ammonia
   • Hydrogen Peroxide
   • Phenol
   • Tham
4. Switch to a graph of pH vs. log(Acid Concentration)
5. Notice that the graph has no middle area that would correspond to approximation B