What is a Base in Chemistry: A Beginner’s Guide

The concept of acids and bases is quite important in chemistry. You will find them frequently referenced and mentioned in theoretical explanations and practical applications.
In this article, we’re going to learn specifically about bases. We will explore their various definitions, properties, examples, and much more. This guide is ideal for beginners who want to build a basic understanding with easy explanations.
Let’s begin.

Definition of a Base: What is a Base in Chemistry?

There are different ways in which a base is defined in modern chemistry. The three main definitions stem from:

• Arrhenius’ concept of acids and bases
• Bronsted-Lowry theory of acids and bases
• Lewis’ concept of acids and bases

Main Properties of a Base

Here is a list of the main properties of a base:

• Bases are bitter in taste. (Note: It is not advisable to taste any chemicals in a lab.)
• Bases are slippery to the touch. A common example of this in real life is in soaps. Since they are chemically composed of bases, they have a signature slippery feel.1
• Bases turn red litmus blue. The litmus test is one of the quickest and most reliable ways to identify bases in a lab.
• Bases turn phenolphthalein pink.
• They have a pH level of >7.
• Bases react with acids to form salt and water. A base can neutralize an acid. (The use of lime by farmers to neutralize acidic soil is a good example to keep in mind.)

¹The slippery feel comes from protein denaturing.

Examples of a Base + Chemical Compositions

Here are some examples of bases in chemistry along with their chemical compositions.

• Sodium Hydroxide (Caustic soda/Lye)
  • Chemical composition: NaOH
  • Dissolution in water releases Na⁺ and OH^– ions.
• Potassium Hydroxide (Caustic potash)
  • Chemical composition: KOH
  • Dissolution in water releases K⁺ and OH^– ions.
• Calcium hydroxide (Slaked Lime)
  • Chemical composition: Ca(OH)₂
  • Dissolution in water releases Ca²⁺ and 2OH^– ions.

As you can see in the examples above, each compound releases OH- ions when dissolved in water, which satisfies Arrhenius’s concept. (The other two definitions are also satisfied, i.e., proton acceptance and electron donation, but we’re not going to delve into that much detail just yet.)

Bases on the pH scale

The pH scale is used to measure the acidity or basicity of a solution using readings from 0 to 14.

The middle reading of the pH scale, “7”, is described as neutral. Normal drinking water falls within 6.5 to 8.5 on the pH scale, which explains its simple taste that is neither sour (acidic) nor bitter (basic).

Any solution/chemical that has a pH of more than 7 is a base. In other words, we can say that bases have a pH reading of >7. (This is an important concept to keep in mind as it is frequently applied and referenced in labs.)

Here is a visual representation of the pH scale: (In this diagram, “alkaline” can be understood to mean “bases.” We will distinguish between the two in the heading below.)

Are Bases and Alkalis the Same?

An alkali is a water-soluble base.

All alkalis are bases, but not all bases are alkalis. There are many non-soluble bases as well, which would fall outside the definition of an alkali.

The word “alkaline,” as it appears in the diagram above, refers to a solution that possesses the traits of an alkali.

How is a Base Identified?

We mentioned in the “Properties” section that bases turn red litmus blue and phenolphthalein pink.

Let’s learn how these identifying procedures can be carried out in a lab, step by step.

Red Litmus Test

1. Take a drop of the test solution and deposit it on a watch glass or a spot plate’s well.
2. Take a red litmus paper strip and touch it gently to the drop.
3. Wait for a few seconds and observe a change in color.

If the red litmus paper turns blue, it indicates that the solution is basic and has a pH reading of 8 or higher.

Phenolphthalein Test

1. Take 5 mL of the test solution in a test tube.
2. Add a few drops of phenolphthalein to the test tube.
3. Swirl and wait for a few seconds.

If the solution turns pink, it indicates the test solution is a base. If it remains colorless, it means that the solution is neutral or acidic.

What are the Different Types of Bases?

There are two different types of bases: strong bases and weak bases.

• What is a strong base in chemistry? A strong base is one that dissolves completely in water and produces a high concentration of hydroxide ions. The pH value of strong bases is from 11 to 14.
• What is a weak base in chemistry? A weak base partially dissolves in water to release hydroxide ions, the concentration of which is lower. Their pH value is between >7 and 11.

What are the Industrial and Day-to-Day Uses of Bases?

Understanding the industrial and day-to-day uses of bases can help in reinforcing the concept even more.

Here is a brief list of industrial uses.

• Sodium hydroxide is used for manufacturing soap and detergents.
• Calcium hydroxide is used for fertilizer production.
• Magnesium hydroxide (a base) is used for wastewater treatment and manufacturing fire retardants.

Here is a brief list of day-to-day uses.

• Bases are used in antacids, medicines for reducing acidity in the stomach.
• They are also used in drain openers and cleaners.
• Baking soda is used in making cakes and other baked goods. It is a mild base.

Wrapping Up

With that, our guide on “What is a base in chemistry?” comes to an end.
To recap the core concepts…
A base is a chemical compound that releases hydroxide ions when dissolved in water. It can also be defined as a proton acceptor and an electron-pair donor.
Bases have a bitter taste and can be identified using a red litmus test. A basic solution turns red litmus paper blue.
These chemical compounds have many industrial applications and day-to-day uses, including in the manufacture of soap, detergents, drain openers, and antacids.