Question

What are the properties of bases?

Answer 1

Hint: Substances that are bitter in taste, slippery to touch, and neutralize acids to produce salts are termed bases. They turn red litmus paper to blue and increase the pH of the solution above 7. According to Arrhenius, bases are compounds that furnish hydroxide ions in their aqueous solution.

Complete answer:
Any chemical species that is capable of donating electron pairs or hydroxide ions in an aqueous solution are known as bases. General properties of bases include the following points:
- They are generally slippery to the touch.
- Tastes bitter.
- Turns red litmus blue, methyl orange-yellow, and phenolphthalein pink.
- Reacts with acids and neutralizes to form salts. The process is known as neutralization reaction.
- Acts as a catalyst to promote certain chemical reactions.
Examples of bases include the hydroxides of the alkali and alkaline earth metals – NaOH, KOH, etc., and the aqueous solutions of ammonia or its organic derivatives.
There are three theories that define acids and bases from different perspectives.
1 – Arrhenius theory: This was the foremost theory that describes the acids and bases as the compounds that ionize in an aqueous solution to produce hydrogen ions \[\left( {{\text{H}}^{+}} \right)\] and hydroxyl ions $\left( \text{O}{{\text{H}}^{-}} \right)$ respectively.
2 – Bronsted-Lowry theory: This theory says that acids are proton donors while bases are proton acceptors.
3 – Lewis theory: According to Lewis's concept, acids are electron-deficient compounds that are capable of accepting electrons while the bases are electron-rich compounds that are capable of donating their extra pair of electrons.
All three theories are correct but the Lewis theory is the widely accepted general acid-base concept.

Note:
All Bronsted-Lowry bases are Lewis bases but not all Lewis bases are Bronsted-Lowry bases. Some examples of Lewis bases include species with lone pairs such as ammonia and water molecules. Such species donate their lone pairs and act as Lewis bases.