How can a base be defined in chemistry?

A base in chemistry is a substance that can either produce hydroxide ions (OH⁻) in an aqueous solution or accept hydrogen ions (H⁺) from another substance.

There are multiple ways to define a base depending on the theory used:

• Arrhenius definition: A base is a substance that releases OH⁻ ions in water.
  Example: Sodium hydroxide (NaOH → Na⁺ + OH⁻)
• Brønsted–Lowry definition: A base is a substance that accepts a proton (H⁺).
  Example: Ammonia (NH₃) accepts H⁺ to form NH₄⁺
• Lewis definition: A base is a substance that donates an electron pair.

Key characteristics of bases:

• Bitter in taste
• Slippery or soapy feel
• Turn red litmus paper blue
• Can neutralize acids to form salts and water

In practical terms:
Bases are commonly used in cleaning products, soap making, and industrial processes due to their reactive and neutralizing properties.