Acids and Bases
C4 & C8
Acids
Any substance that generates hydrogen
ions (H+) when dissolved in water
Examples:
HCl
HNO3
An acid in water
In water, the hydrogen ion dissociates
from it s compound.
Can be written 2 different ways.
Example:
HCl + H2O→
But more commonly written
HCl (aq) →
Acids in water
Show the following acids in water.
HNO3
H2SO4
H3PO4
Bases
An Ionic compound made up of a positive ion
(Cation) and a negative ion (Anion). Many
bases contain the anion – hydroxide (OH-)
Examples:
NaOH
KOH
LiOH
A base in water
A base dissociates into a cation and anion.
Example:
In H2O
NaOH (s) →
Bases in water
Show the following bases in water.
LiOH →
Ca(OH)2 →
Al(OH)3 →
pH of acids and bases
pH of 7 means
H+ concentration = OH- concentration
pH of 1 means
H+ concentration = .1M
OH- concentration =.0000000000001M (.
1 x 10-12)
Strength of acid
Extent of H+ production when the acid is
dissolved in water.
When a strong acid dissolves in water
almost every acid molecule dissociates
into H+. When a weak acid dissolves in
water only some of the acid molecules
will dissociate into H+
Strength of base
Extent of OH- production when the base
is dissolved in water.
When a strong base dissolves in eater
almost every base molecule dissociates
into OH-. When a weak base dissolves in
water only some of the base molecule
will dissociate into OH-.
How do we show the
difference in strength?
A strong acid dissociation is shown with
A weak acid dissociation is shown with
HCl – a strong acid
HCl (aq)
H2CO3 – a weak acid
H2CO3 (aq)
How do we show the
difference in strength?
A strong base dissociation is shown with
A weak base dissociation is shown with
NaOH – a strong base
NaOH (aq)
Be(OH)2 – a weak Base
Be(OH)2 (s)
Try on your own
Nitric acid (HNO3) is a strong acid. Show its
dissociation in water.
Sulfurous acid (H2SO3) is a weak acid. Show its
dissociation in water.
Potassium hydroxide (KOH) is a strong base. Show
its dissociation in water.
Barium hydroxide (Ba(OH)2) is a weak base. Show
its dissociation in water.
Neutralization
Supplement
Neutralization
Reaction of an acid and base that yields
a solution with a pH of 7
@ pH=7 the amount of H+ = OHreaction where water is also a product
Total Ionic Equation
An expression that indicates what is
occurring in a neutralization.
Shows all ions present.
Total Ionic Equation
Example: HCl and NaOH are mixed together
until a neutralization occurs this would be
shown with the following equation:
Spectator Ions
Ions that are present but do not participate in the
reaction
H+(aq)+ Cl-(aq) +Na+(aq) + OH-(aq) → H2O(l) + Na+(aq) + Cl-(aq)
Spectator Ions
Net Ionic Equation
An expression that leaves out the spectator ions.
H+ (aq) + OH- (aq) ! H2O(l)
**This is ALWAYS the net ionic equation for any
acid / base titration if the base contains OH-!
Titration
Neutralization reaction where a solution of
pH=7 is produced
In this solution moles of acid = moles of base
So MAVA = MBVB
MA = Molarity of Acid
VA = Volume of Acid
MB = Molarity of Base
VB = Volume of Base
Titration
Example: 10mL of .15M HCl is needed to
neutralize 16mL of NaOH. What is the molarity of
NaOH?