Identifying Acids and Bases • Acids

• Acid (anhydrides)

• Bases

• Base (anhydrides)

• Salts

contains H+ ions as the cation, with and other element as the anion

Non-metal oxide

Contains OH- as the anion

Combined with a cation

A metal with oxygen

Ionic compound

Formed from a cation and an anion

Metal and non-metal

H2SO4

HI

P2O5

Ca(OH)2

Al2O3

Mg F2 KClLiBr

Acid / Base Chemistry•Hydrogen ion concentration = [H+]•Hydroxide ion concentration =

[OH-]

•Pure H20 – neutral substance – –ph=7 and [H+]=[OH-]

•H2O will self-dissociate

– H20 > H+ + OH-

– Note: the number of H2O molecules that will self dissociate is very small; only 2 molecules per a billion, therefore [H2O] is unchanged.

Acid / Base Chemistry- Kw - is the ion product constant for

water

- Kw = 1.0 x 10-14 M2

Kw= [H+] [OH-]

FOR H2O:Kw= [1.0 x 10-7 M][1.0 x 10-7M]

- there is an indirect relationship between [H+] and [OH-]

Acid / Base Chemistry•Calculate [OH-] if [H+] is 1.0 x 10-2 M

• Kw= [H+] [OH-]

• [OH-]= Kw = 1.0 x 10-14M2

• [H+] 1.0 x 10-2M

• [OH-]= 1.0 X 10 –12 M

Acid / Base Chemistry•Calculate [H+] if [OH-] is 6.5 x 10-

11 M

• Kw= [H+] [OH-]

• [H+]= Kw = 1.0 x 10-14M2

[OH-] 6.5 x 10-11M

• [H+]=

• [H+] will tell us if a soln is acidic or basic.

Acidic solutions

Neutral solutions

Basic solutions

pH= 1- 6

[H+]= 1.0 x 10 M – 1.0 x 10 M

[H+] > [OH-]

-1 -6

pH= 7

[H+] = [OH-]

1.0 x 10 M for both -7

pH= 8 -14

[H+]= 1.0 x 10 M – 1.0 x 10 M

[H+] < [OH-]

-8 -14

Acid / Base Chemistry• If [H+]= 1.0 x 10-9M, will the solution be

basic or acidic?• Basic• Why?• because the pH= 9 and this solution

contains less [H+] than [OH-]

Acid / Base Chemistry• If [OH-]= 2.63 x 10-4M, will the solution be

basic or acidic or neutral?• • Why?

Acid / Base Formulas• pH= -log [H+] • pOH= -log [OH-] • pH + pOH =14• [H+] = antilog (-pH)• [OH-] = antilog (-pOH)

• How to use the calculator!!

• Calculate the pH of a solution with [H+] = 0.001 M. Is this acidic, basic, or neutral?

Acid / Base Formulas• Calculate the pH of a solution with [OH-] = 7.9

x 10-3 M. Is this acidic, basic, or neutral?

• Calculate the pH of a solution with [H+] = 4.2 x 10-6 M. Acidic, basic, or neutral?

What is the [OH-]?

Acid / Base Formulas• A solution with a pH of 9.1 has what [H+]?

– 2nd log –9.1 ENTER

• What is the [OH-]?

• What is the pOH?

Scientists Who Define Acids / Bases

•Arrhenius:Acids: Any substance which releases H+ ion in water solution.Bases: Any substance which releases OH- ion in water solution.

Scientists Who Define Acids / Bases

•Bronsted - Lowry:Acids: Any substance which donates a proton.Bases: Any substance which accepts a proton.

Acids, Bases, and Their Conjugates

• Water is amphoteric – has basic + acidic properties.

• Conjugate Acid: Substances formed in a reaction when a base gains a H+

• Conjugate Base: Substances formed in a reaction when an acid donates H+

Acids, Bases, and Their Conjugates

• NH3 + H2O -- NH4+ + OH-

• HCl + H2O --->

Acids, Bases, and Their Conjugates

• CO3-2 + H2O ---> HCO3

- + OH-

• Ca(OH)2 + 2HNO3 --> Ca(NO3)2 + 2HOH

Identifying monoprotic, diprotic, and triprotic:

monoprotic:

HCl H+ + Cl-

diprotic:

H2SO4 H+ + HSO4-1

HSO4-1 H+ + SO4-2

triprotic:

H3PO4 H+ + H2PO4-1

H2PO4-1 H+ + HPO4-2

HPO4-2 H+ + PO4-3

Strengths of Acids and Bases

• Strong acids and bases will completely dissociateex. HCl --> H+ + Cl-

• The six strong acids - HCl, HBr,

• HI, H2SO4, HNO3, HClO4

• All others are weak.• Strong Bases: Groups I• and II with OH- except Be

Strengths of Acids and Bases

•Weak acids and bases slightly dissociateex. HClO <--> ClO- + H+

Electrolytes and Non-Electrolytes

•Strong Electrolytes:- Compounds that conduct electricity in aqueous solution- Substances that completely dissociate- Strong acids and bases- Soluble salts

Electrolytes and Non-Electrolytes

•Weak Electrolytes:- Slight electron conductivity- Slight dissociation in aqueous- Weak acids and bases- Insoluble salts if in molten state

Electrolytes and Non-Electrolytes

•NonElectrolytes:- Don’t conduct electricity - No ions to carry current- Organic, molecular

Examples of Electrolytes and Nonelectrolytes:

• H2S03

• weak acid/weak elect.

• CsOH

• strong base/strong elect.

• HCl04

• strong acid/strong elect.

• C6H1206

• nonelectrolyte- covalent, molecular, organic b/c carbon

Examples of Electrolytes and Nonelectrolytes:

• Al(OH)3

• weak base/weak electrolyte

• HF

• weak acid/weak electrolyte

• CCl4

• nonelectrolyte- molecular compound

• NaN03

• soluble salt/strong electrolyte

• S03

• acid anhydride/weak electrolyte

Neutralization Reactions:

General Equation:

• Acid + Base Salt + Water

• HCl + NaOH NaCl + HOH

Acid Base Salt Water

Neutralization Reactions:

Titration: Analytical method used to determine the concentration of acids and bases in a neutralization reaction.

1. Measured volume of an acid or base with unknown concentration. Put in Erlenmeyer.

2. Add a few drops of indicator to the Ernlenmeyer.

3. A measured volume of titrant is delivered into the flask through a buret (base or acid)

4. Concentration of the titrant is known –Standard Solution.

5. Neutralization occurs when indicator is revealed End Point

6. Equivalence Point MOL ACID = MOL BASE

Titration Curve

Neutralization practice problems:

1. What volume of calcium hydroxide in a 3.0 M solution is needed to neutralize 45.0 mL of 2.6 M perchloric acid?

Neutralization practice problems:

2. Determine the [Ba(OH)2] solution if 300.0 mL was titrated to neutrality with 220.5 mL of 6.0 M solution of phosphoric acid?

Neutralization practice problems:

1. What volume of calcium hydroxide in a 3.0 M solution is needed to neutralize 45.0 mL of 2.6 M perchloric acid?

G: 45 mL

2.6 M HCl04

3.0 M Ca(OH)2

U: ? vol Ca(OH)2

Ca(OH)2 + HCl04 2 HOH + Ca(Cl04)2

0.45 L HCl04 x 2.6 mol HCl04 x 1 mol Ca(OH)2 x 1 L Ca(OH)2

1 L Ca(OH)2 2 mol HCl04 3 mol Ca(OH)2

vol mol mol volM CR M

2. Determine the [Ba(OH)2] solution if 300.0 mL was titrated to neutrality with 220.5 mL of 6.0 M solution of phosphoric acid

G: 220.5 mL

6.0 M H3P04

300.0 mL Ba(OH)2

U: ? M Ba(OH)2

3Ba(OH)2 + 2H3P04 Ba3(P04)2 + 6HOH

0.2205 L H3P04 x 6.0 mol H3P04 x 3 mol Ba(OH)2

1 L H3P04 2 mol H3P04

= 1.985 mol Ba(OH)2

1.985 mol Ba(OH)2

0.300L Ba(OH)2

vol mol mol M CR

= 6.62 M Ba(OH)2

Dissociation examples

Acid/Base Chemistry

• Hydrogen ion concentration= [H+]

• Hydroxide ion concentration= [OH-]

• Pure HOH= neutral substance.

• Kw is constant for water. [Kw= 1E-14 M2]

More Acid/Base Chemistry

• Kw = [1x10-7 M][1x10-7 M] (Kw=[H+][OH-])

• Most other substances are not neutral

• Indirect relationships between [H+] and [OH-]

• [H+] will tell us if solution is Acidic or basic.

Strengths of Acids and Bases

•Strong Acids: HCl, HI, HBr, H2SO4, HNO3, HClO4

•Strong Bases: Groups I and II with OH- except Be

Identifying Electrolytes and Nonelectrolytes:

Strong Electrolytes:

-compounds that conduct electricity in aqueous solutions

-substance that completely dissociate

-strong acids and bases

-soluble salts

Weak Electrolytes:

-slight electrical conduct

-slight dissociation in aqueous solution

-conducts in molten state

-weak acids and bases

-insoluble salts (if in molten state)

Nonelectrolytes:

-don’t conduct electricity

-no ions to carry current

-organic, molecular

Neutralization

• Acid + Base > Salt + H2O• Neutralization is found using

titration• Titration: Analytical method

used to determine the concentration of acids, bases in a neutralization reaction.

Neutralization reactions

• Products always end in a salt and water.

• Acid + Base = Salt + HOH

• Titration- Analytical method used to determin the concentration of acids in a neutralization reaction.

Theory