Weak vs. Strong Acids and Bases

1. The strength of an acid or base depends on its ability to dissolve in water. The dissolving process can be represented by an equilibrium equation in either of two forms:
   1. HA_(aq) H⁺¹_(aq) + A^-1_(aq)
      or
      
   2. HA_(aq) + H₂O_(l) H₃O⁺¹_(aq) + A^-1_(aq)
2. The equilibrium constant for this equation is given the symbol Ka.
3. So, in general
4. The further the equilibrium lies to the right the stronger the acid and the higher the Ka value. See the list of Ka values for more detail.
5. The stronger the acid the more ions that are formed. See illustration below of a strong and weak acid dissolved in solution:

   Weak Acid	Strong Acid

6. A good example of a weak acid is phenolphthalein: Click here to see how it works.

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