What are they?
There are different definitions for acids and
bases depending on the circumstances.
Acid—produces hydrogen ions
(H+) in solution
Bases—produces hydroxide ions
(OH-) in solution
1.
2.
3.
4.
5.
6.
7.
Acids
react with carbonates to produce
carbon dioxide gas.
change pink phenolphthalein to
colourless
make litmus paper turn red or stay red
make bromothymol blue turn yellow
taste sour
have a pH below 7
react with most metals producing
hydrogen gas
1.
2.
3.
4.
5.
6.
Bases
don’t react with carbonates to produce
carbon dioxide gas.
change colourless phenolphthalein to
pink
make litmus paper turn blue or stay
blue
make bromothymol blue stay blue
taste bitter
have a pH above 7
Common Acids
Acid
Formula
Weak or
Strong
Use
Sulfuric Acid
H2S04
Strong
Car batteries
Hydrochloric
Acid
HCl
Strong
Stomach
Acetic Acid
CH3COOH
Weak
vinegar
Phosphoric
Acid
H3PO4
Strong
Softdrinks,
fertilizers
Nitric Acid
HNO3
Strong
Nitroglycerine,
fertilizers,
plastics
Common Bases
Base
Formula
Weak or
Strong
Use
Ammonia
NH3
Weak
Windex
Sodium
Hydroxide or
Lye
NaOH
Strong
Drain Cleaners
Calcium
Carbonate
CaCO3
Weak
Antacids such
as Tums,
Rolaids
Potassium
hydroxide
KOH
Strong
Bio diesel,
soaps
What substances in water make acids acidic and
bases alkaline?
•All aqueous solutions have H+ ions and OH1- ions.
•When the quantities of these ions are equal the
solution is neutral since the H+ ions and OH1- ions
combine to form H2O.
•Lets look at an aqueous solution below:
Is the solution below acidic or
basic?
basic
Notice water molecules will
sometimes break apart.
•The pH scale has been established to
measure the quantities of H+ and OH1in a aqueous solution.
•A neutral substance with a pH of 7 has
1+
1equal quantities of H and OH .
•An acidic substance has a pH below 7.
•A basic substance has a pH above 7.
More H1+ than OH1- More OH1- Than H1+
-1 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
N
Increasing
basicity
Increasing acidity
e
How much more
Since this is a
acidic is pH 1 than u
logarithmic scale
t pH 9 is 10x’s more
pH 5?
r basic than pH 8, pH
10 000 x’s
What pH is 1000x’s a
12 is 1000 x’s more
more acidic than
l basic than pH 9
pH 2? pH of -1
Acid - Base Neutralizations
Acids and bases react producing salt and
water.
HCl + NaOH  NaCl + H2O
What kind of a reaction is this?
A double displacement.
NaOH
HCl
What are the products?
H2O and NaCl
Water and an ionic compound or
an ionic salt
HCl
NaOH
What are the products when carbonic
acid is added to calcium hydroxide?
1st write the balanced chemical
equation
H2CO3 + Ca(OH)2  CaCO3 + 2 H2O
The salt’s name is
calcium carbonate
What are the products when nitric acid
is added to potassium hydroxide?
1st write the balanced chemical
equation.
HNO3 + KOH  KNO3 + H2O
The salt’s name is
potassium nitrate
What are the products when chloric
acid is added to lithium hydroxide?
1st write the balanced chemical
equation.
HClO3 + LiOH  LiClO3 + H2O
The salt’s name is
lithium chlora
Antacids (ex. Tums or Rolaids)
•Antacid tablets used to treat
excess stomach acid (heartburn)
are reallybases which neutralize
acids.
•Antacids cause a neutralization
reaction in your stomach that
produces salt and water.
Factors that Affect an Acid or
Base’s Strength
1. Concentration
 More molecules of acid or base per
litre of water
Factors that Affect an Acid or
Base’s Strength
2. Percent Ionization
 Strong acids and bases have a high percent ionization
 A high % of molecules of strong acid will break
into ions (ionize) when mixed with water
Ex #1. HCl

H+
+ Cl100 molecules
99 cations
99 anions
 A low % of molecules of weak acid will break into
ions (ionize) when mixed with water
Ex #1. CH3COOH

H+
+ CH3COO100 molecules
4 cations
4 anions
Oxides of Elements
• Metal oxides in aqueous solutions tend to
produce bases
Ex. Sodium reacting in water produces Sodium
hydroxide
• Non-metal oxides in aqueous solutions tend
to produce acids
Sulfur and nitrogen oxides react with water to
produce sulfuric acid and nitric acid (cause of
acid precipiation)