Transcript Acids and Bases

Acids and Bases
Drill – 4/23/08
• Write everything you know about
acids and bases!
Drill – 4/30/08
• Write the equation for the
neutralization reaction between
carbonic acid and calcium
hydroxide.
Chemical
Vinegar
Lemon Juice
Windex
Shampoo
Conditioner
Clear soda
KOH
Distilled Water
Baking Soda
solution
HCl
HNO3
Salt Water
Oil
Sugar water
Drain cleaner
Tilex
Gatorade
Hand soap
Ammonia
Prediction
Litmus paper rb
Litmus paper br
pH
Properties of Acids (in aq solution)
1. Sour taste
2. Low pH
3. Turn litmus paper red
4. Conduct electrical
current
Properties of Bases (in aq solution)
1. Bitter taste
2. Slippery
3. High pH
4. Turn litmus paper blue
5. Conduct electrical
current
Arrhenius Definition
Acid = substance that releases
+
H ions in aq solution
HCl  H+ + ClBase = substance that releases
OH- ions in aq solution
+
NaOH  Na + OH
Bronsted-Lowry Definition
As more and more substances
were determined to have acidic or
basic properties, even some
without obvious H+ or OH-, a new
definition was needed.
• Acid = proton donor
• Base = proton acceptor
Bronsted-Lowry Definition
• Acid = proton donor
H2O + HCl  H3O+1 + Cl-1
Bronsted-Lowry Definition
• Base = proton acceptor
NH3 + H2O  NH4+ + OH–
Acid-Base Reactions
• Known as a neutralization
reaction. Acids and bases will
react with each other to form
water and salt.
HCl + NaOH  H2O + NaCl
Day 2
Acid Naming Overview
Binary
Start with hydroElement
End with –ic acid
Tertiary
“I ate something, and now I am sick”
If anion ends in –ate then the acid ends in –
ic
If the anion ends in –ite then the acid ends
in -ous
Acids & Bases Review
• Acid
– substance that releases H+ ions in aq solution
– Proton donor
– Electron pair acceptor
• Base
– substance that releases OH- ions in aq
solution
– Proton acceptor
– Electron pair donator
Acid Strength
A stronger acid will transfer
MORE protons (H+) than a weak
acid. It will create more
hydronium ions (H30+) in water.
Hydrochloric acid
HCl + H20 
H30+
+
Cl-
More dissociation!
Acetic Acid
CH3COOH + H20  H30+ + CH3COOLess dissociation!
How do we compare the
strength of an acid or a base?
We measure the amount of
hydronium ions they create
(acids) or the amount of
hydroxide ions they create
(bases)….using concentration.
What is concentration?
• Using molarity, it is a measure of
moles of solute in liters of
solution.
• Concentration is measured in
WATER!
H2O is both an acid and a base
Water is simultaneously donating
and accepting protons!
What are the ion concentrations in water?
• The concentrations of H3O+ and
OH- in pure water are each
1.0x10-7 mol/L at 25ºC.
• Putting a symbol in brackets is
used to signify the concentration.
• [H30+] = 1.0x10-7 M
• [OH-] = 1.0x10-7 M
Ionization Constant of water, KW
• KW = [H30+] [OH-]
• KW = (1.0x10-7)(1.0x10-7)
= 1.0x10-14
• Acids increase the
Whenever [H30+] is
greater than [OH-], the
solution is acidic.
• Bases increase the [OH-]
Whenever [OH-] is
greater than [H30+], the
solution is basic.
[H30+]
With an increase
in [H30+], some
of the H30+ ions
will react with the
OH- ions,
reducing [OH-] .
[H30+][OH-] will
still = 1.0x10-14
• Concentration values tend to be
small…so we use a more
convenient scale. pH!
pH + pOH = 14
• pH – A measure of the acidity of a
solution. It is the negative
logarithm of the hydronium ion
[H30+] concentration.
pH = -log [H30+]
pH + pOH = 14
• pOH – A measure of how basic a
solution is. It is the negative
logarithm of the hydroxide [OH-]
concentration.
pOH = -log [OH-]
• The logarithm base 10 of a
number x is the power to which
10 must be raised in order to
equal x.
• Log 10 x = ?
• 10? = x
Log 100 = ?
10 ? = 100
• Remember, our concentrations
are SMALL. So we are going to
be dealing with decimals…
• Log 10 x = ?
• 10? = x
Log .001 = ?
10 ? = .001
[H+] = 1.00 x 10-3 = 0.001
pH = -log [H+]
pH = -log (1.00 x 10-3)
pH = 3
To determine pH from a
concentration where 1 is the
only digit, write the
concentration in scientific
notation. The exponent will
be the pH.
• For a base, you do the same
thing except remember that you
are solving for pOH first…
Solutions
1.0x10-3M
HClO4
0.010 M HCl
0.000001 M
HBr
1.0 x 10-4
KOH
0.10 M
NaOH
0.003 H2SO4
[H+]
pH
[OH-]
pOH