• pH less than 7
• Neutralizes bases
+
• Forms H ions in solution
• Corrosive-reacts with most
metals to form hydrogen gas
• Good conductors of
electricity
HNO3 + H2O
 H3O+ + NO3
•HCl- hydrochloric- stomach acid
•H2SO4- sulfuric acid - car batteries
•HNO3 – nitric acid - explosives
•HC2H3O2- acetic acid - vinegar
•H2CO3-carbonic acid – sodas
•H3PO4- phosphoric acid -flavorings
Strong Acids are Strong Electrolytes



They dissociate completely in water.
100% of the HA molecules break up into H+ and A- ions.
There are six common strong acids chemists MUST
know:

1.
2.
3.
4.
5.
6.
HCl
HI
HBr
HNO3
HClO3
H2SO4
-
Hydrochloric Acid
Hydroiodic Acid
Hydrobromic Acid
Nitric Acid
Chloric Acid
Sulfuric Acid *1st dissociation only
Weak Acids are Weak Electrolytes



They DO NOT dissociate completely in water.
1% of the HA molecules break up into H+ and A- ions.
There are five common weak acids chemists MUST
know:

1.
2.
3.
4.
5.
HF
H3PO4
HC2H3O2
H3BO3
C6H8O7
-
Hydrofluoric Acid
Phosphoric Acid *1st dissociation only
Acetic Acid
Boric Acid *1st dissociation only
- Citric Acid
 pH
greater than 7
 Feels slippery
 Dissolves fats and oils
 Usually forms OH ions in
solution
 Neutralizes acids




NaOH- sodium hydroxide (LYE) soaps, drain
cleaner
Mg (OH)2 - magnesium hydroxide-antacids
Al(OH)3-aluminum hydroxide-antacids,
deodorants
NH4OH-ammonium hydroxide- “ammonia”
Strong Bases are Strong Electrolytes



They dissociate completely in water.
100% of the BOH molecules break up into B+ and OH- ions.
There are eight common strong bases chemists MUST know:

1.
2.
3.
4.
5.
6.
7.
8.
KOH
NaOH LiOH CsOH RbOH Ba(OH)2 Ca(OH)2 Sr(OH)2 -
Potassium Hydroxide
Sodium Hydroxide
Lithium Hydroxide
Cesium Hydroxide
Rubidium Hydroxide
Barium Hydroxide
Calcium Hydroxide
Strontium Hydroxide
Weak Bases are Weak Electrolytes



They DO NOT dissociate completely in water.
1% of the BOH molecules break up into B+ and OH- ions.
There are six common weak bases chemists MUST
know:

1.
2.
3.
4.
5.
6.
NH3
C5H5N
CH3NH2
C3H5O2NH2
Be(OH)2
Mg(OH)2
- Ammonia
- Pyridine
- Methylamine
- Alanine
- Beryllium Hydroxide
- Magnesium Hydroxide




In the 1800’s chemical concepts were based on
the reactions of aqueous solutions.
Svante Arrhenius developed a concept of acids
and bases relevant to reactions in H2O.
Arrhenius acid – produces hydrogen ions in
water.
Arrhenius base – produce hydroxide ions in
water.
A broader ,more modern concept of acids and
bases was developed later.
Bronsted-Lowry acid- donates a hydrogen ion in a
reaction.
Bronsted – Lowry base – accepts a hydrogen in a
reaction.


Conjugate acid- compound formed when an
base gains a hydrogen ion.
Conjugate base – compound formed when an
acid loses a hydrogen ion.




Acids can be classified by how many H+ ions
per molecule are given.
Monoprotic acids
Diprotic acids
Polyprotic acids
Ex:
H2SO4(aq) + H2O
HSO4- (aq) + H2O

H3O+ + HSO4-(aq)
H3O+ + SO42-(aq)

Proton Transfer
This occurs in every acid-base reaction.
 When acids and bases react, a proton is transferred
from the acid to the base.
 This is the driving force of acid-base reactions.
 Once the proton is transferred, it is in a position of
less chemical potential.


Formation of water
If the acid contains H+ and the base contains OHthe acid base reaction will form water.
 The remaining cation and anion form a salt.


If both the acid and base are weak, no reaction
occurs because no ions are present to initiate
the proton transfer.




HCl + H20  H3O + + Cl(more hydronium ions, more acidic)
NaOH in water  Na+ + OH(more hydroxide ions, more basic)
NaOH + HCl  NaCl + HOH
Acid + Base yields type of salt and water
NH3 + H20  NH4+ + OHammonia
gas + water yields ammonium and hydroxide
ions


Acid-Base Reactions are also called
Neutralization Reactions
Acids and Bases are extremely corrosive
materials.
This means that they destroy things they come into
contact with, including skin, plant tissue, and even
metals when the acid or base is strong enough.
 For this reason, chemists should be VERY careful when
handling them.


When acid-base reactions occur, corrosive
materials become harmless materials (water and
salt).

Another way to say this is to say that they are
neutralized.



Consider the reaction between nitric acid and
potassium hydroxide.
Molecular Equation
HNO3(aq) + KOH(aq)  KNO3(aq) + H2O(l)
Complete Ionic Equation – both acid & base
dissociate.
H+(aq) + NO3-(aq) + K+(aq) + OH-(aq)  K+(aq) + NO3-(aq) + H2O(l)

Net Ionic Equation – always shows formation of
water.
H+(aq) + OH-(aq)  H2O(l)



Consider the reaction between acetic acid and
sodium hydroxide.
Molecular Equation
HC2H3O2(aq) + NaOH(aq)  NaC2H3O2 (aq) +
H2O(l)
Complete Ionic Equation – only the base
dissociates.
HC2H3O2(aq) + Na+(aq) + OH-(aq)  Na+(aq) + C2H3O2-(aq) + H2O(l)
Net Ionic Equation
HC2H3O2(aq) + OH-(aq)  H2O(l) + C2H3O2-(aq)




Consider the reaction between hydrochloric acid
and ammonia.
Molecular Equation
HCl(aq) + NH3 (aq)  NH4+(aq) + Cl-(aq)
Complete Ionic Equation – only the acid
dissociates.
H+(aq) + Cl-(aq) + NH3(aq)  NH4+(aq) + Cl-(aq)

Net Ionic Equation
H+(aq) + NH3(aq)  NH4+(aq)
pH of Common Substances
Timberlake, Chemistry 7th Edition, page 335
Indicator
Acid
color
Neutral
color
Base
color
Phenolphthalein Colorless Faint pink Dark pink
Bromthymol
blue
Yellow
Green
Blue
Litmus
Red
-----
Blue

pH paper changes
color to indicate a
specific pH value.

A buffer is a solution that resists changes in pH
when small amounts of acids and bases are
added.





“Heartburn”
Planting vegetables and flowers
Fish Tanks and Ponds
Blood
Swimming pools
Pollution in the air (sulfur dioxide, carbon
dioxide, nitrogen dioxide) combines with
water to form various acids.
.
Rapid changes in pH can kill fish and other
organisms in lakes and streams.
Soil pH is affected and can kill plants and
create sinkholes