The Nature of Acid-Base Equilibria Section 8.1 The Nature of Acid-Base Equilibria

Brønsted-Lowry Acids/Bases A Brønsted-Lowry acid is any compound which can donate a proton (H+). A Brønsted-Lowry base is a cmpd that accepts a proton. HCl is the acid b/c it donates the H+ H2O is the base b/c it accepts the H+

BLA, BLB, CA, BB A pair of compounds or ions that differ by the presence of one proton (H+). In every reaction that involves and acid or a base, there is a conjugate acid-base pair. Label the BL acid, BL base, the conjugate acid and the conjugate base

Some Specifics… A substance is classified as a Brønsted-Lowry acid or base only for a specific reaction. Some substances are amphoteric (or ambiprotic) which means they can act as either a Brønsted-Lowry acid or base depending on the reaction.

If the acid/base is Strong (ionizes 100%), the equilibrium lies entirely to the right. However, if the acid/base is a Weak (ionizes < 100%), the equilibrium is dependent on the acid/base equilibrium constant: Ka or Kb

Ka Expression

Kb Expression

Auto Ionization of Water All samples of water contain an equilibrium mixture of water and its ions. The ion product constant for water (Kw)

The acid equilibrium constant and the base equilibrium constant for a conjugate acid and a conjugate base can be related. Therefore, if you know the Ka for a weak acid (HA), you can calculate the Kb for its conjugate base (A-).

Some More Details… The stronger an acid, the weaker its conjugate base And, conversely The weaker the acid the stronger its conjugate base

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