Educational Materials for Organic Chemistry

Acid-Base Equilibria Tutorial - Learning Goals

If you aren't sure how to go about learning about acid-base chemistry using this tutorial, refer to one or more of the following questions to guide your eplorations.

The Effect of pH

• Use the tutorial to lower the pH to some value below the current value and answer the following questions:
  • What happens to the concentration of bromoacetic acid (A) if you lower the pH of the solution? Does this make sense based on the fact that there is a higher concentration of H⁺ (or H₃O⁺) in solution at a lower pH?
  • What happens to the concentration of the conjugate base of bromoacetic acid (B) if you lower the pH of the solution? Does this make sense based on the concentration of H⁺ at low pH?
• Based on what you have discovered so far, can you predict what will happen to the concentrations of bromoacetic acid (A) and its conjugate base (B) if you raise the pH? Use the tutorial to check to see if your prediction is correct.
• Use the tutorial to collect data on the concentrations of bromoacetic acid (A) and its conjugate base (B) at each pH you can choose. Plot pH along the x axis and concentration on the y axis. You may want to plot concentration of A in one color and concentration of B in a second color. You should also plot the total concentration (A form + B form). What happens to the total concentration as pH changes?

The Effect of Temperature

• Select a temperature different from the current temperature, and answer the following questions.
  • Did the concentrations change? (did you expect them to?)
  • Based on any changes in concentrations, do you think heat is absorbed, given off, or not changed during the forward reaction?
  • What (if anything) else changed?

The Effect of Volume

• If you lower the volume, what happens to the concentrations of bromoacetic acid (A) and its conjugate base (B)?
• If you raise the volume, what happens to the concentrations of bromoacetic acid (A) and its conjugate base (B)?
• Do these results make sense considering that water does not appear on either side of the net reaction?

Last modified 9/24/97