Acids
and
Bases
Acids: Compounds that dissociate
(give off) one or more hydrogen
ions (H+) when dissolved in water
(proton donors)
Bases: Compounds that dissociate
(give off) one or more hydroxide
ions (OH-) when dissolved in
water (proton acceptors)
The pH Scale
pH is a measure of H+ ion concentration.
The formula for calculating pH is:
pH = -log[H+]
The pH Scale
pH = -log[H+]
I Do: A solution has a hydrogen ion concentration
of 0.001 M. What is the pH of this solution?____
We Do: What is the pH of a solution with a
hydrogen ion concentration of 0.0001 M?_______
You Do: What is the pH value of a solution that
has a hydrogen ion concentration of 0.0000005
M?_______
The pH Scale
Acids have a pH value less than 7. Bases have a pH
value greater than 7. Neutral substances have a pH
of exactly 7. (Alkaline is another way to say basic)
pH Indicators
An indicator is a compound used to detect the presence of H+ ions in
solution. Indicators typically change color when exposed to acids and
bases and can be used to determine whether a substance is acidic,
basic, or neutral. Some common indicators are:
Litmus paper (turns red when exposed to acid, blue when exposed to
base)
Phenolphthalein (clear = acid, pink = base)
Universal indicator (red = acid, blue = base)
Bromothymol blue (yellow = acid, blue = base)
Cyanidin (red cabbage juice) (red = acid, yellow/green = base)
Phenol red (yellow = acid, red = base)
Properties of Acids
 Acids taste sour
Acids have a pH lower than 7
Acids effect indicators
Blue litmus turns red
Universal indicator turns red
Properties of Acids
Acids are proton (hydrogen ion, H+)
donors
 Acids react with active metals,
produce H2
 Acids react with carbonates
 Acids neutralize bases
Acids Effect Indicators
Blue litmus paper turns red in contact
with an acid.
Acids Have
a pH less
than 7
Properties of Bases
 Bases taste bitter
Bases have a pH greater than 7
 Bases effect indicators
 Red litmus turns blue
Universal indicator turns blue
Phenolphthalein turns purple
Properties of Bases
Bases are proton (H+) acceptors
and usually have hydroxide ions- OH Solutions of bases feel slippery
 Bases neutralize acids
Bases Effect Indicators
Red litmus paper turns blue
in contact with a base.
Phenolphthalein
turns purple in a
base.
Bases have
a pH
greater
than 7
Common Strong Acids
Sulfuric Acid, H2SO4
Perchloric acid, HClO4
Hydrochloric Acid, HCl
Hydrobromic Acid, HBr
Nitric Acid, HNO3
Hydroiodic Acid, HI
Common Strong Bases
Lithium Hydroxide, LiOH
Sodium Hydroxide, NaOH
Potassium Hydroxide, KOH
Calcium Hydroxide Ca(OH)2
Strontium Hydroxide, Sr(OH)2
Barium Hydroxide, Ba(OH)2
Common Weak Acids
Formic Acid, HCOOH
Acetic Acid, CH3COOH
Hydrofluoric, Acid HF
Hydrocyanic acid, HCN
Common Weak Bases
Sodium hydroxide, NaOH
Ammonia, NH3
Potassium hydroxide, KOH
Calcium hydroxide, Ca(OH)2
Formation of Hydronium ion, H3O+
H2O +
Proton
acceptor
HCl
Proton
donor

H3O+ + ClHydronium
Acids and Bases Can Be Strong
or Weak
Strong acids are assumed to be 100%
ionized in solution (good proton donors).
HCl
H2SO4
HNO3
Weak acids are usually less than 5%
ionized in solution (poor proton donors).
H3PO4
HC2H3O2
Organic acids
Strong Acid Dissociation
Weak Acid Dissociation
Acids Can Be Strong or Weak
Which acid is a strong
acid?____________
How do you know?
Which acid is a weak
acid? ___________
How do you know?
Acids and Bases Can Be
Concentrated or Dilute
A concentrated solution contains a high
amount of solute per liter of solution.
Example: 12M HCl
A dilute solution contains a low amount
of solute per liter of solution.
Example: 0.01 M HCl
Acids and Bases Can Be
Concentrated or Dilute
A
B
Which solution is most concentrated? ___
How do you know?
Which solution is lease concentrated?___
How do you know?
Neutralization
What happens when an acid is mixed with a base?
Neutralization!
Products of Neutralization
HCl + NaOH 
NaCl + H2O
H2SO4 + Ca(OH)2  CaSO4 + 2 H2O
The products of neutralization are always
salt and _______.
water
a ______