Weak Acids and Bases

One of the most important chemical types that you will study in your chemistry courses are acids and bases. Testing the acidic or basic nature of chemicals is one of the first steps in their characterization. In organic and inorganic chemistry, it is essential that one determines the inherent acidic and basic nature of any chemical, as it matters when you are choosing it for a specific application.

What are Weak Acids?

There are various ways in which acids can be defined. Some definitions are very specific, while some are very general. Most simply, acid is any chemical that generates Hydrogen ions (H⁺) when dissolved in water. Acids are also defined as proton (H⁺) donors. A more general definition of acid is the following. An acid is any chemical which accepts an electron pair when it reacts with other substances. This last definition was provided by Lewis, and acids satisfying the condition are called Lewis acids. Acids strongly react with metals and taste sour. A blue litmus paper will turn red, when it comes in contact with an acid. A chemical with a pH less than 7 is acidic.

The strength of an acid can be determined by how readily it dissociates in water to release Hydrogen ions (H⁺), along with negative ions. Weak acids are defined as a class of acids which only partially dissociate in water. To put it simply, they do not completely ionize in water. In contrast, strong acids completely dissociate in water to release protons in the process. They are the most common of acids found in nature.

Examples of Weak Acids

Any chemical which has an ionizable proton could be a weak acid. Here are some of the most common weak acids found in nature.

• Formic Acid (HCOOH)
• Acetic Acid (CH₃COOH)
• Hydrofluoric Acid (HF)
• Hydrogen Sulfide (H₂S)
• Hydrocyanic (HCN)

What are Weak Bases?

A base is any chemical which dissociates in water to release hydroxide ions (OH^-). Bases are also defined as proton acceptors or donors of electronic pairs. The electron pair donor definition is again attributed to Lewis and the ones that satisfy that condition are known as Lewis bases. Acids and bases are exactly complementary to each other. When an acid and a base come together, they neutralize each other, forming salts. A chemical with a pH greater than 7 is basic.

A weak base is any chemical, that weakly dissociates into water to produce hydroxide (OH^-) ions. They are basically weakly ionizing bases in a water solution. These are the most common ones found in nature.

Examples of Weak Bases

Here are the most common ones found in nature.

• Ammonia (NH₃)
• Pyridine (C₅H₅N)
• Trimethylamine (N (CH₃)₃)
• Diethylamine (CH₃CH₂)₂NH

Weak acids and bases are more common than their strong counterparts, as they find many applications in our day-to-day life. Understanding acidic and basic nature of chemicals is important in scientific and industrial applications of acids and bases.