theories of acid bases and salts

Arrhenius theory of acid and bases

BRONSTED LOWERY CONCEPT OF ACID AND BASES

equasion for acid -- HA(aq) → H+(aq) + A–(aq)

equation for base -- BOH(aq) → B+(aq) + OH–(aq)

Bronsted acid is a substance which donates an H+ ion or a proton and forms its conjugate base

Bronsted base is a substance which accepts an H+ ion or a proton and forms its conjugate acid.

equasion - Base + Acid ⇌ Conjugate acid + conjugate base

examples - HCl + NH3 → NH4+ + Cl– in this reaction, HCl donates its proton to NH3. Therefore, HCl is a Brønsted-Lowry acid. Since NH3 has a lone pair which it uses to accept a proton, it is a Brønsted-Lowry base.

NH3 +H2O → NH4 + OH- in this reaction NH3 is the base and forms the conjugate acid NH4 while water is the acid forming conjugate base OH-

Arrhenius acid is a substance that dissociates in water to form hydrogen ions (H+).

example - HCl(aq) + H2​O(l) → H3​O+(aq) + Cl−(aq)

Lewis acid and bases

A Lewis acid is a substance that accepts a pair of electrons to form a covalent bond.

A Lewis base is a substance that donates a pair of electrons to form a covalent bond.

examples of Lewis concept - Al3+(aq) + 6 H2O(l) <-----> Al(H2O)63+(aq) the Al(H2O)63+ ion is formed when an Al3+ ion acting as a Lewis acid picks up six pairs of electrons from neighboring water molecules acting as Lewis bases to give an acid-base complex, or complex ion.

Equasion lewis acid + lewis base → adduct / acid-base complex,

Example 2 - BF3 is the acid while NH3 acts as a base

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An Arrhenius base is a substance that dissociates in water to form hydroxide (OH–) ions

example - NaOH(aq) → Na+(aq) + OH–(aq)