College Chemistry Ch 8

Acids and Bases

Acids

a substance, when dissolved in water, dissociates to produce hydrogen ions

proton (H⁺) donor

Bases

a substance, when dissolved in water, dissociates to produce hydroxide ions

proton (H⁺) acceptor

Amphiprotic

–a substance possessing both acid and base properties

–Water is the most commonly used solvent for both acids and bases

–Solute-solvent interactions between water and both acids and bases promote solubility and dissociation

Conjugate Acid

what the base becomes after it accepts a proton

BH⁺ is the ____ ____ of the base B

Conjugate Base

what the acid becomes after it donates its proton

-A^- is the ____ ____ of the acid HA

Conjugate Acid-Base Pair

the acid and base on the opposite sides of the equation

Acid and base strength

degree of dissociation; Not a measure of concentration

HCl, HBr, HI 

Hydrochloric Acid

HNO₃ 

Nitric Acid

H₂SO₄

Sulfuric Acid

HClO₄

Perchloric Acid

NaOH

Sodium Hydroxide

KOH

Potassium Hydroxide

Ba(OH)₂

Barium Hydroxide

Weak acids and bases

only a small percent dissociates (Weak electrolytes)

hydronium ion

H₃O⁺

ion product constant for water

K_w = [H₃O⁺][OH^-]

pH scale

•a scale that indicates the acidity or basicity of a solution

–Ranges from 0 (very acidic) to 14 (very basic)

pH = -log[H₃O⁺]

Calculating pH

1.0 x 10^-14 = [H₃O⁺][OH^-]

pH = -log[H₃O⁺]

Neutralization reaction

the reaction of an acid with a base to produce a salt and water

Net ionic equation

–Show only the changed components

–Omit any ions appearing the same on both sides of equation (Spectator Ions)

Titration

An analytical technique to determine the concentration of an acid or base

involves the addition of measured amount of a standard solution to neutralize the second, unknown solution

Standard solution

solution of known concentration

Buret

long glass tube calibrated in mL which contains the standard solution

Equivalence point

The ____ ____ is when the moles of H₃O⁺ and OH^- are equal

Indicator

a substance which changes color as pH changes

Polyprotic substance

donates or accepts more than one proton per formula unit

Buffer solution

•solution which resists large changes in pH when either acids or bases are added

•These solutions are frequently prepared in laboratories to maintain optimum conditions for chemical reactions

Buffer Capacity

a measure of the ability of a solution to resist large changes in pH when a strong acid or strong base is added

•Also described as the amount of strong acid or strong base that a buffer can neutralize without significantly changing pH

Equilibrium

constant expression and the pH expression can be combined

Polyprotic substance

donates or accepts more than one proton per formula unit

monoprotic

–HCl is ____ producing one H⁺ ion for each unit of HCl

diprotic

Sulfuric acid is ____ each unit of H₂SO₄ produces 2 H⁺ ions