Acid and Base Definitions

Objectives:• 1. State the Bronsted-Lowry definition of acids

and bases.• 2. Identify the common physical and chemical

properties of acids and bases.Key Terms:• Acid base indicator, neutralization reactions,

hydronium ion, amphoteric, conjugate acid, conjugate base

Basic Properties

Acid BaseTaste sour tasting - lemon bitter tasting - aspirinTouch feel like water on skin feel slippery on skinReaction on metal

reacts with metal does not react with metal

electrical conductivity

electrolyte - good conductor electrolyte - good conductor

indicator turns litmus red turns litmus blueNeutralization

neutralized when mixed with a base to form a salt

neutralized when mixed with an acid to form a salt

Arrhenius Definition• An acid is a substance that releases (dissociates) Hydrogen

ions (H+) in water – monoprotic - releases 1 H+ ion (HCl) – diprotic - releases 2 H+ ion (H2SO4) – triprotic - releases 3 H+ ion (H3PO4)

• An base is a substance that releases (dissociates) Hydroxide ions (OH-) in water – ex: KOH, NaOH, Ca(OH)2, Mg(OH)2

Bronsted-Lowry Definition• An acid is a proton (H+) donor • A base is a proton acceptor • conjugate acid-base pairs are substances related by the loss or

gain of a H+ ion – strong acids have a weak conjugate base – weak acids have a strong conjugate base

Conjugate acid/base pair

Conjugate base/acid pair

Lewis Acid Definition• Lewis Acid and Bases An acid is an electron pair acceptor

– A base is an electron pair donor – H+ + OH- g H2O

• In this reaction the H+ ion accepts the electron pair donated by the OH- ion to form H2O