Unit 7: Equilibrium And Acids

Section 5: Acid-Base Basics

Introduction

Basics

Acid-Base Pairs

Introduction

In this unit, we will deal with acids and bases. In the real world, acids and bases are very important. For instance, have you ever seen someone scoop water out of a pool and put drops into it. If so, you have just seen one of the many uses of acids and bases because the person doing that task was checking the acidity of the water. Acids and bases have a lot of math associated with them, and many of the important chemistry tests ask you to do the math on acids and bases, so it is important to understand it, but it also gets complicated, so we at Chem101decided that this is not something that we wished to try to explain. We do suggest that you ask a parent or teacher to explain the math behind the concept of acids and bases.

Basics

All teachers love to ask you what Arrhenius's concepts of acids were and what the Bronsted-Lowry model about acids said, so pay attention! Arrhenius said that acids produce H⁺ ions and bases produce OH^- ions. The Bronsted-Lowry model states that acids are H⁺ donors and bases are H⁺ acceptors. (Memorize these two concepts!)

Acid-Base Pairs

In the reaction above, HA is the acid. (The acid is normally on the reactants side of the reaction) and H₂O si the bases (it is also normally on the reactants side.) Easy, huh? Now, we have to locate the conjugate acid and the conjugate base. The conjugate acid is the substance that accepts the H⁺ so in our example H₃O⁺ is our conjugate acid. (Please note that the base accepts that H⁺ from the acid. It is a good check step.) The conjugate base is the A^-, and it is the result of the acid losing the H⁺. In the reaction above, the acid is placed into water and it breaks up into a cation and anion. This is called dissociation.