CHEM 5013 CHEM 5013 Applied Chemical Applied Chemical

PrinciplesPrinciples

Acid / Base ChemistryAcid / Base Chemistry

Professor BensleyProfessor BensleyAlfred State CollegeAlfred State College

Chapter ObjectivesChapter Objectives

Recognize common strong acids and Recognize common strong acids and bases and common household acids bases and common household acids and bases.and bases.

Identify acids, bases and conjugate Identify acids, bases and conjugate acid-base pairs according to the acid-base pairs according to the Bronsted-Lowry definitions.Bronsted-Lowry definitions.

Chapter ObjectivesChapter Objectives

Write molecular and ionic equations Write molecular and ionic equations for acid-base neutralization for acid-base neutralization reactions.reactions.

Understand the water ionization Understand the water ionization constant and realize how that is used constant and realize how that is used to calculate pH, pOH, [Hto calculate pH, pOH, [H33OO++], and ], and [OH[OH--]]

Acids and BasesAcids and Bases

Acids:

Examples:Examples: Bases:

Examples:Examples:

Household Acids and BasesHousehold Acids and Bases

BrBröönsted-Lowry Conceptnsted-Lowry Concept Acids: Bases:

H+

H+

NH3 (aq) + H20 (l) Base Acid

NH4+ (aq) + OH-

(aq)

HNO3 (aq) + H20 (l)

NO3- (aq) + H3O+

(aq)Acid Base

Conjugate Acid – Base PairsConjugate Acid – Base Pairs

NHNH33 (aq) + H (aq) + H22O NHO NH44++ (aq) + OH (aq) + OH-- (aq) (aq)

BASEBASE ACID ACID CONJ. ACID CONJ. ACID CONJ. BASE CONJ. BASE

OROR

NHNH33 (aq) + H (aq) + H22O NHO NH44++ (aq) + OH (aq) + OH-- (aq) (aq)

CONJ. BASECONJ. BASE CONJ. ACID ACID CONJ. ACID ACID BASE BASE

ExampleExample1.1. Identify the acid and the base species in Identify the acid and the base species in

the following reaction:the following reaction:

COCO332-2- (aq) + H (aq) + H22O (l) O (l) HCO HCO33

-- (aq) + OH (aq) + OH-- (aq) (aq)

2.2. Label each species as an acid or base. Label each species as an acid or base. Show the conjugate acid/base pairs.Show the conjugate acid/base pairs.

CC22HH33OO22-- (aq) + HNO (aq) + HNO22 (aq) (aq) HC HC22HH33OO2 2 (aq) + NO(aq) + NO22

-- (aq)(aq)

Acid / Base StrengthsAcid / Base Strengths

Strong acid:

Six main strong acids: Six main strong acids:

HClOHClO4 4 , H, H22SOSO44 , , HI, HCl, HBr, HNOHI, HCl, HBr, HNO33

Weak acid:

Acid / Base StrengthsAcid / Base Strengths

Strong base:

Six main strong bases: Six main strong bases:

LiOH, NaOH, KOH, Ca(OH)LiOH, NaOH, KOH, Ca(OH)22 , Sr(OH) , Sr(OH)22 , , Ba(OH)Ba(OH)22

Note: Group IA and IIA metals!!!Note: Group IA and IIA metals!!!

Weak base:

Neutralization ReactionsNeutralization Reactions

Acid + Base Acid + Base Salt + Salt + WaterWater

2HCl(aq) + Ca(OH)2HCl(aq) + Ca(OH)22(aq) (aq) CaCl CaCl22(aq) + (aq) + 2H2H22O(l)O(l)

Water Ionization ConstantWater Ionization Constant KKww==

What if I add a strong acid to water?What if I add a strong acid to water?

0.10M HCl in H0.10M HCl in H22O O What is [H What is [H33OO++]? ]? What What is [OHis [OH--]?]?

What if I add a strong base to water?What if I add a strong base to water?

0.10M NaOH in H0.10M NaOH in H22O O What is What is [H[H33OO++]? ]? What What is [OHis [OH--]?]?

ExampleExample

Calculate the [HCalculate the [H33OO++] and [OH] and [OH--] ] at 25at 25°C in 1.4 x 10°C in 1.4 x 10-4-4 M M Mg(OH)Mg(OH)22 a strong base. a strong base.

Neutral, Acidic and Basic Neutral, Acidic and Basic SolutionsSolutions

Neutral solution: Neutral solution:

Acidic solution:Acidic solution:

Basic solution:Basic solution:

pH ScalepH Scale

pH =pH =

[H3O+] = 0.1M pH =

[H3O+] = 0.01M pH =

[H3O+] = 0.001M pH =

pH ScalepH Scale

What is the pH of a neutral solution?What is the pH of a neutral solution? What is the pH of an acidic solution?What is the pH of an acidic solution? What is the pH of a basic solution?What is the pH of a basic solution?

ExampleExample

What is the pH of typical adult blood What is the pH of typical adult blood where [Hwhere [H33OO++] = 4.0x10] = 4.0x10-8-8 M M

pH CalculationspH Calculations

pOH =pOH =

pH + pOH = pH + pOH =

Example: What is the pOH of typical adult Example: What is the pOH of typical adult blood?blood?

pH CalculationspH Calculations

[H[H33OO++] = ] =

Typical adult blood has a pH of Typical adult blood has a pH of 7.40. What is [H7.40. What is [H33OO++]?]?

1 2 3 4 5 6 7 8 9 10 11

pH

Methyl Violet

Phenolphthalein

Bromthymol Blue

Bromcresol Green

Universal Indicator

Methyl Orange

10-1 10-2 10-3 10-4 10-5 10-6 10-7 10-8 10-9 10-10 10-11

[H3O+]

Common Acids and BasesCommon Acids and Bases

Acids:Acids: Hydrochloric Acid – Hydrochloric Acid – Sulfuric Acid – Sulfuric Acid – Nitric Acid – Nitric Acid – Acetic Acid – Acetic Acid –

Bases:Bases: Sodium Hydroxide – Sodium Hydroxide – Ammonia – Ammonia –