CR - Acid-Base Reactions (Lesson)

Acid-Base Reactions

Another kind of double displacement reaction takes place when an acid and base react with each other. First, you will need to learn the definition of acids and bases. There are several ways to define these terms. The one most used in AP Chemistry is the Bronsted-Lowry definition where acids are proton donors and bases proton acceptors. Now, realize a proton is simply a hydrogen ion. So when we consider something a proton donor, it contributes hydrogen ions into a solution. 

       

In an aqueous solution, water can act as a Bronsted-Lowry acid OR a base, depending on the solute in the solution.
In the following image, water acts as an acid in a basic solution:
       
In the following image, water acts as a base in an acidic solution:
       

You Try It: Acid-Base Reactions

Naming Acids

Before we go any further, a quick review of the names for these substances. 

The naming of ionic bases follows the rules you already know for naming ionic compounds. For example, NaOH is sodium hydroxide. For molecular bases, you will need to memorize the common ones. NH3 is ammonia. CH3NH2 is methylamine.

Acids are named according to a new set of rules.

Binary acids, meaning they contain hydrogen and one other nonmetal, are named with the prefix hydro- and the ending -ic.

For example, HCl gas is hydrogen chloride, but HCl (aq) is hydrochloric acid. H2S is hydrosulfuric acid.

Acids that contain hydrogen, oxygen, and another element are called oxoacids. These do not use the prefix hydro. Instead, they are named with the endings, -ic and -ous, followed by the word acid.

  • Polyatomic ions that have the ending - ate change the ending to - ic.
  • (An easy way to remember this is "I ate it, it made me sick!")
  • Polyatomic ions that have the ending - ite change the ending to - ous.
  • (An easy way to remember this is "A bad dog will bite us.")

For example, to name HNO3(aq), look at the name of NO3-.  NO3- is nitrate. Nitrate changes to nitric. So, HNO3 (aq) is nitric acid.

Neutralization Reactions

The H+  ion in the acid reacts with the OH-  ion in the base, causing the formation of water. Generally, the product of this reaction is an ionic salt and water: acid + base LaTeX: \longrightarrow⟶ salt + water.

Neutralization Reaction Example 1

Neutralization Reaction Example 2

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