Compare and contrast the Arrhenius Br nsted-Low... - SS2 Chemistry Acids, Bases, and pH Question

Arrhenius Theory:

●     Definition: According to Arrhenius, an acid is a substance that dissociates in water to produce hydrogen ions (H+), while a base is a substance that dissociates in water to produce hydroxide ions (OH-).

●     Examples: Hydrochloric acid (HCl) dissociates in water to produce H+ ions, making it an Arrhenius acid. Sodium hydroxide (NaOH) dissociates in water to produce OH- ions, making it an Arrhenius base.

Brønsted-Lowry Theory:

●     Definition: Brønsted-Lowry defines an acid as a substance that donates a proton (H+) and a base as a substance that accepts a proton (H+).

●     Examples: Hydrochloric acid (HCl) donates a proton to water, forming the hydronium ion (H3O+), making it a Brønsted-Lowry acid. Ammonia (NH3) accepts a proton from water, forming the ammonium ion (NH4+), making it a Brønsted-Lowry base.

Lewis Theory:

●     Definition: Lewis defines an acid as a substance that accepts an electron pair, and a base as a substance that donates an electron pair.

●     Examples: Boron trifluoride (BF3) accepts an electron pair from a molecule like ammonia (NH3), making it a Lewis acid. Ammonia donates an electron pair, making it a Lewis base.

While all three theories provide different perspectives on acids and bases, they are interconnected. The Arrhenius theory focuses on ionisation in water, while the Brønsted-Lowry theory extends the concept to include proton transfer in any solvent. The Lewis theory broadens the definition further by considering electron pair transfer, which encompasses a wider range of acid-base reactions.