Difference Between Conjugate Base and Conjugate Acid

A conjugate acid is formed when a base gains a proton, while a conjugate base is formed when an acid loses a proton. They are related pairs in a chemical reaction, differing by the presence or absence of a proton.

What Is Conjugate Acid?

A conjugate acid is a substance formed when a base accepts a proton (H⁺ ion) during a chemical reaction. This transformation occurs as part of the Bronsted-Lowry acid-base theory, which defines acids as proton donors and bases as proton acceptors.

For example, consider the reaction between ammonia (NH₃) and water (H₂O). In this reaction, ammonia acts as a base by accepting a proton from water:

NH₃ + H₂O → NH₄⁺ + OH⁻

In this equation, ammonia (NH₃) accepts a proton from water (H₂O) to form its conjugate acid, ammonium ion (NH₄⁺). Water, which donates a proton, becomes the conjugate base in this reaction (OH⁻). So, NH₄⁺ is the conjugate acid of NH₃, and OH⁻ is the conjugate base of H₂O. Conjugate acids and bases are essential concepts in understanding acid-base chemistry and pH.

What Is Conjugate Base?

A conjugate base is the species that remains after an acid donates a proton (H+) in a chemical reaction. It is formed by accepting the proton from the acid.

 For example, consider the reaction between acetic acid (CH3COOH) and water (H2O)

CH3COOH + H2O ⇌ CH3COO- + H3O+

In this reaction, acetic acid donates a proton

Conjugate acid Vs conjugate base

The main differences between conjugate acid and conjugate base are given below:

CharacteristicConjugate AcidConjugate Base
DefinitionGains a proton (H+)Loses a proton (H+)
Chemical FormulaHAA-
ChargePositive (+)Negative (-)
Relationship to BaseForms from a baseTransforms from an
Higher AcidityLower pH (more H+)Higher pH (less H+)
StrengthStrong or WeakStrong or Weak
ExampleHCl -> Cl-NH4+ -> NH3

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