Arrhenius Definition of

• Acids

• Bases

- Substances that produce hydrogen ions, H+ when dissolved in water

- Substances that produce hydroxide ions, OH- when dissolved in water

HCl H+ + Cl-

NaOH Na+ + OH-

What is ammonia?

NH3

Acid or base?

Bronsted-Lowry Definition of

• Acids

• Bases

- Any substance in a chemical reaction that donates H+ ( a proton)

- Any substance in a chemical reaction that accepts H+ (a proton)

HCl + H2O H3O+ + Cl-

NH3 + H2O ↔ NH4+ + OH-

Hydronium ion

• Reversible reaction indicates products reform reactants

• Base does not completely ionize

• Base is weak

• Can look at the reaction in reverse

NH3 + H2O ↔ NH4+ + OH-

Acetic acid, HC2H3O2, is a weak acid

• Write a reaction to describe its dissociation

• Label the acid, base, conjugate acid and conjugate base

Naming

• What are some acids (names/formulas)?

1. Name: HBr, KOH, NH3, Al(OH)3, H2SO3, H2SO4, H3PO4, H2S,

CU(OH)22. Write formulas for: nitrous acid, barium hydroxide, hydrofluoric acid,

nitric acid, ammonia, silver hydroxide, acetic acid

Lewis Definition of

• Acids

• Bases

- Any substance in a chemical reaction that accepts an electron pair

- Any substance in a chemical reaction that donates an electron pair

NH3 + H2O ↔ NH4+ + OH-

H H H H-N: + H-O: <-> H-N-H + :O-H H H

+ -

: ::

Do now

• Name NaOH, HClO, HC2H3O2, NH3

• Write formulas for sulfuric acid, nitric acid, potassium hydroxide

Complete this reaction

H2O(l) + H2O(l) <-> H3O+(aq) + OH-

(aq)

Acid Base Conj. Acid Conj. Base

Kw = [H3O+][OH-] = 1 x 10-14 (at 25ºC)

In pure water, at 25ºC, what would the hydronium and hydroxide ion concentrations be???[H3O+] = [OH-] = 1x10-7 M

For any aqueous solution!!!

• Find the hydronium ion concentration for eggs whose hydroxide ion concentration is 1.6x10-8 M. Is this sample acidic or basic?

• What is the hydroxide ion concentration for a soft drink whose hydronium ion concentration is 5.8 x 10-4M. Is this solution acidic or basic?

Do Now:• What is the hydronium ion? How does it

relate to the hydroxide ion concentration?• Find the hydronium ion concentration of a

cleaning product whose hydroxide ion concentration is 0.054 M

• What is … 102? 103? 10-1? 10-4?• What power is ten raised to… to get 10?

100? 0.1? 0.01? 10-7?• Tell me everything you know about pH.

What is pH?• pH = -log [H3O+]

• What is the pH of pure water at 25ºC whose hydronium ion concentration is 1x10-7 M

• What is the pH of a cleaning product whose hydroxide ion concentration is 1x10-3M? Is it acidic or basic?

Do now

• What is pH?

• What does it measure? How do we find it? What does it tell us?

• What is pOH? How does it relate to pH?

• What differentiates a strong acid from a weak acid?

Kw = [H3O+][OH-]= 1x10-14

pH = -log[H3O+]pOH = -log[OH-]

pH + pOH = ?14

10 –pH = [ H3O+]

What is the pH of a 1.0 M HCl solution?

•Write a reaction for the dissociation•Does it dissociate completely or reversibly?•Use stoichiometry to relate concentration of reactants and products.

What is the pH of a 1.0 M HC2H3O2 solution?

What is the pH of a 1.0 M Sr(OH)2 solution?

What is the pH of a 1.0 M HC2H3O2 solution?

What is the pH of a 1.0 M NH3 solution?

What is the concentration of all species present in the above solutions?

DO NOW:DO NOW:What is the pH of a 1.0 M Sr(OH)2 solution? What is the concentration of all species present in the above solutions?

What is the concentration of all species present in a 1.0 M ammonia solution? What is the pH?

Strong acids??? Strong bases???

HCl, HBr, HI, HNO3, HClO4,

H2SO4

Group I and II metal hydroxides

Polyprotic Acid

Do Now

• What is a pH indicator?

• What is the pH of a 0.1 M HCl solution?

• What is the pH of a 0.01 M NaOH solution?

• What is the concentration of a solution prepared by taking 1 mL of 0.01 M NaOH and dissolving it in sufficient water to create 10 mL of solution?

What is a pH indicator?• Chemical compounds that are added to a

solution so the pH can easily be determined

• Weak organic acid and its conjugate base

• Acid represented by HIn (to simplify)

• Write a dissociation reaction for the “acid”, HIn

HIn + H2O <-> In- + H3O+

Color 1 Color 2

Phenolphthalein, C20H14O4

Do Now:1. A solution has a pH of 4.5. Is it acidic or basic?

What is the hydronium ion concentration?

2. How are hydronium and hydroxide ion concentrations related?

3. How do you calculate pH and pOH and how are they related?

4. How do you determine the pH of a strong acid or base? Describe the steps.

5. How do you determine the pH of a weak acid or base? Describe the steps.

What is a salt?

• Crystalline compound composed of the negative ion of the acid and the positive ion of the base

NaCl

NaOH HClStrong Strong Base Acid

Neutral Salt

Ammonium Chloride

• Write the formula of this salt

• Identify the parent acid and base that produced this salt

• Is this salt acidic, basic, or neutral?

• If so, which part of this salt acts as the acid or base? Write a hydrolysis reaction for the acidic or basic ion. (hydrolysis = put it in water)

Sodium Acetate

• Write the formula of this salt

• Identify the parent acid and base that produced this salt

• Is this salt acidic, basic, or neutral?

• If so, which part of this salt acts as the acid or base? Write a hydrolysis reaction for the acidic or basic ion

What is a buffer?

• A buffered solution resists a change in pH

• What must it be made of?

Weak acid and its salt or a weak base and its salt

Contain relatively large concentrations of weak acid and corresponding weak base. Works as long as concentrations of buffering materials are large compared to amount of H+ or OH- added.

What is an Acid-Base Titration?

• Laboratory technique to determine the concentration of acid or base

• React a solution whose concentration you know (Standard) with a solution whose concentration is unknown

• Example: Standard is 1.25 M HCl solution, NaOH solution concentration is unknown. Write a reaction for this neutralization.

•Beaker contains 50.0 mL of 1.25 M HCl and a few drops of phenolphthalein•Slowly start adding the base, NaOH, whose concentration is unknown•Eventually will reach the equivalence point moles H+ = moles OH- Do you know that you have reached the equivalence point?Go one drop past, and now solution is basic - You have reached the endpoint

Buret,NaOH

HCl

NO!

moles H+ = moles OH-

• To reach endpoint, 73.6 mL of base was required

What if acid is diprotic?• Use normality (another measure of concentration)

• Normality is ratio of equivalents/liter

• An equivalent isThe amount of acid that will donate 1 mole H+

The amount of base that will accept 1 mole of H+

At equivalence point… mole H+ = mole OH-

NaVa = NbVb

Try these!• What is the concentration (molarity and

normality) of HCl if 40.0 mL is required to reached the endpoint when titrated against 85.0 mL of 0.50 M Sr(OH)2?

• What is the volume of 0.75 M H2SO4

required to reach the endpoint when titrated against 300. mL of 1.25 M NH3?

At what pH will the equivalence point occur?

What is the pH of 1.0 M HC2H3O2 solution? Look in your notes.

• What is the effect of dissolving sodium acetate in this solution? What will happen to the pH?

Common ion effect – addition of a common ion increases the concentration of one of the products thereby shifting the reaction toward the opposite side

Calculate the pH of a solution that is 1.0 M acetic acid and 1.0

M sodium acetate.