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
Stays clear
Turns Red
Turns pink
Turns Blue
Reaction with Indicators:
Phenolphthalein
Litmus
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
Strong and Weak Acids
• 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
1.3%
Vinegar: HC2H3O2(aq) 
H+
(aq)
+
C2H3O2-(aq)
>99%
Hydrochloric Acid: HCl(aq) 
H+(aq) + Cl-(aq)
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
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/L
pH 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:
𝐻 + = 10−𝑝𝐻
• The following equation can be used to determine the pH for a given
hydrogen ion concentration
𝑝𝐻 = −𝑙𝑜𝑔 𝐻 +
Practice
1) 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