Warm-Up: Acid Base Nomenclature• Identify each compound as an acid or a base• Provide the IUPAC name for each of the following:

a) BaOH(aq) b) HF(aq) c) HClO4(aq) d) HCl(aq) e) KOH(aq)

• Provide the classical name for each of the following:

a) HBr(aq) b) H2SO3(aq) c) H2S(aq) d) HClO4(aq)

Acids and Bases: Part I

LG: I can describe the Arrhenius theory of acids and bases and what makes an acid strong or weak

Recall: Properties of Acids and Bases

Property Acids Bases

pH <7 >7

Taste Sour Bitter

Feel Water-like Slippery

Reaction with Metal Reacts No reaction

Reaction with Indicators:

PhenolphthaleinLitmus

Stays clearTurns Red

Turns pinkTurns Blue

Arrhenius Theory• Svante Arrhenius was the first scientist to determine that

electrolytic solutions contain dissociated ions• Since acids and bases also conduct electricity, he

concluded that they must also contain ions

Defining Acids and Bases• Arrhenius bases – A substance that dissociates to

produce hydroxide ions, OH-, when dissolved in water• Ca(OH)2(s) Ca2+

(aq) + 2 OH-(aq)

• Arrhenius acid – a substance that ionizes to produce hydrogen ions, H+, when dissolved in water.• HNO3(aq) H+

(aq) + NO3-(aq)

Acid-Base Neutralization• Arrhenius applied his theory of acids and bases to explain why

the mixing of an acid with a base, produces a neutral solution:

HCl(aq) H+(aq) + Cl-

(aq)

NaOH(aq) Na+(aq) + OH-

(aq)

Applications of Neutralization Reactions• Acid wear on teeth• Acids can solubilize basic compounds in

tooth enamel• Signs of wear: translucency, yellowing,

sensitivity • Acid reflux (“heartburn”)• Stomach acid splashes up into esophagus• Esophagus does not contain a

protective mucus layer like the stomach

• It is well known that vinegar is less dangerous than hydrochloric acid because vinegar has a higher pH; but what causes this difference?• The answer is the degree to which an acid will ionize

Vinegar: HC2H3O2(aq) H+(aq) + C2H3O2

-(aq)

Hydrochloric Acid: HCl(aq) H+(aq) + Cl-

(aq)

1.3%

>99%

Strong Acids Weak Acids

Hydrochloric Acid, HCl

Phosphoric Acid, H3PO4

Nitric Acid, HNO3 Ethanoic Acid, HC2H3O2

Sulfuric Acid, H2SO4

Carbonic Acid, H2CO3

Perchloric Acid, HClO4

Methanoic Acid, HCO2H

Strong and Weak Acids

Homework

• Pg. 469 #1, 4, 6, 7 • Pg. 475 # 1, 3, 4, 6, 12

Acids and Bases II

LG: I can describe the Bronsted-Lowry definitions of acids and bases and perform calculations relating hydrogen ion concentration and pH

Bronsted-Lowry Theory of Acids and Bases• Arrhenius’ theory of acids and bases is limited by the inability to

explain the basic properties of substances like ammonia (NH3), that do not contain hydroxide ions, OH-

• Johannes Bronsted and Thomas Lowry redefined acids and bases in broader terms:• Acid – Hydrogen ion donor• Base – Hydrogen ion acceptor

Conjugate Acids and Bases

• In the following example, which substance is the acid and which is the base?

HCl(aq) + NH3(aq) NH4+(aq) + Cl-(aq)

• A conjugate base is the product formed as the result of an acid losing a proton• A conjugate acid is the product formed as the result of a base gaining

a proton

Strange Brew…

•Water is often referred to as being amphiprotic or amphoteric meaning that is can sometimes act as an acid and sometimes as a base.

• Acts like a base: H2SO4(aq) + H2O(l) HSO4-(aq) + H3O+

(aq)

• Acts like an acid: NH3(aq) + H2O(l) NH4+

(aq) + OH-(aq)

pH• pH or “Power of Hydrogen” is a scale which indicates the

concentration of hydrogen ions in a solution• The higher the concentration of hydrogen ions, the more acidic the

solution will be.• Each pH unit corresponds to a factor of 10 in the concentration

How many times more acidic is a lemon compared to milk?

Calculating pH• pH is defined as “the negative of the exponent to the base 10 of

the hydrogen ion concentration” pH 7

Acidic > 1.0 x 10-7 mol/L > Basic (neutral)

pH 9 = 1.0 x 10-9 mol/LpH 2 = 1.0 x 10-2 mol/L

Try These…pH_____ = 1.0 x 10-5 mol/L

pH_____ = 6.2 x 10-4 mol/L

pH_____ = 4.7 x 10-11mol/L

Calculating pH• The following equation can be used to determine the hydrogen ion

concentration for a given pH:

• The following equation can be used to determine the pH for a given hydrogen ion concentration

Practice1) The pH of a solution is 10.33. Determine the hydrogen ion

concentration.

2) A solution has a hydrogen ion concentration of 4.7 x 10-11 mol/L. Determine the pH of the solution.

Homework

• Pg. 475 # 5, 7, 8, 10 + Handout to practice pH calculations