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Notes 16.1. Acids and bases. Acids and Bases. Acids- sour taste Bases- bitter taste and slippery feel Arrhenius model- acids produce hydrogen ions in an aqueous solution where bases produce hydroxide ions
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Notes 16.1 Acids and bases
Acids and Bases • Acids- sour taste • Bases- bitter taste and slippery feel • Arrhenius model- acids produce hydrogen ions in an aqueous solution where bases produce hydroxide ions • Bronsted-Lowry model- an acid is a proton (H+) donor, and a base is a proton acceptor • Conjugate acid- is formed when the proton is transferred to the base • Conjugate base- everything that remains of the acid molecule after a proton is lost • H3O+hydronium ion
Acid Strength • Strong acid- an acid that completely dissociates to produce H+ions in solution • Weak acid- an acid that dissociates to a slight extent in aqueous solution • A strong acid contains a relatively weak conjugate base- one that has a low attraction for protons ( figure 16.1) • Common strong acids- sulfuric acid, hydrochloric acid, nitric acid, perchloric acid ( page 568)
Water as an acid and a base • A substance is said to be amphoteric if it can behave either as an acid or as a base. Water is the most common. • Kw is the ion-product constant [H+] [OH-] = 1.0 x 10-14 = Kw at 25 degrees Celcius • In aqueous solution at 25 C, no matter what is contains, the product of [H+] and [OH-] must always equal 1.0 x 10-14 • [ ] indicate the molarity • An acidic solution, where [H+]> [OH-] • A basic solution, where [OH-] > [H+] • A neutral solution, where [H+] = [OH-] • In each case, Kw = [H+] [OH-] = 1.0 x10-14
Examples • Calculate [H+] or [OH-] as required for each of the following solutions at 25oC, and state whether the solution is neutral, acidic, or basic. • A. 1.0 x 10-5 M OH- • B. 1.0 x 10-7 M OH- • C. 10.0 M H+