Introduction to
ACIDS and BASES
Warm Up
1. Title your CBWhat are Acids and Bases?
2. Write everything you know about the
properties of acids and bases.
3. Why are they important?
Acids and Bases are part of your
everyday lives!
Acids
Bases
Definition
An acid is a compound that produces
hydrogen ions (H+) when dissolved in
water.
A base is a compound that produces
hydroxide ions (OH-) when dissolved in
water.
Properties of Acids and Bases
•
•
•
•
Acids
Sour taste
Neutralize bases
Release hydrogen
gas when added to
an active metal
Aqueous solutions
of acids are
electrolytes
(conduct electricity)
•
•
•
•
Bases
Bitter taste
Feels slippery
Neutralize acids
Aqueous solutions
of bases are
electrolytes
(conduct electricity)
What do you think?
1. Based on the properties of the following, predict
if the product is an acid or base.
a. Shampoo
b. Lemonade
c. Windex
d. Gatorade
2. Do you think Draino is an acid or a base?
Why?
Warm Up
Things I am collecting:
Article Analysis
Chapt 12.1 Notes
Molarity Packet
Review
Things I have already
collected:
KNO3 Lab
Solubility Rule Lab
Solubility Curve WS
(not the one with water)
Rainbow Tube Demo
What is happening in the tube?
WATER
Self Ionization of Water
Water molecules collide with one another to
cause the self-ionization reaction
represented by this equation:
2H2O
H3O+ + OHIt is a reversible reaction so the equation is
usually written with the arrows going in
both directions:
2H2O
H3O+ + OH-
Self Ionization of Water
In pure water the H+ and OH- are produced
in a 1:1 ratio.
[H+] = [OH-]
A neutral solution is when [H+] = [OH-]
Water is a Neutral Solution!
Self Ionization of Water
In any aqueous solution [H+] and [OH-] are
interdependent.
[H+] increases then [OH-] decreases.
[H+] decreases then [OH-] increases.
This is an example of Le Chatelier’s
Principle.
Le Chatelier’s Principle
Equilibrium
H2O
H+ + OH-
If a stress is applied to a system in a
dynamic equilibrium, the system changes
to relieve the stress.
Le Chatelier’s Principle
If we add more reactants the system looks
like this:
However, the system will correct itself and
make more products to balance the
system.
Le Chatelier’s Principle
Similarly, if we add more products to the
system, it will look like this:
But a system that is in equilibrium will shift
again to relieve stress:
Equilibrium Constant
For every reaction there is a mathematical
relationship between the reactants and products.
Keq = [Products]x
[Reactants]x
Where X are the coefficients in the
balanced equation.
Example
Write the equilibrium constant for the
following reaction.
H2SO4 + 2NaOH
Na2SO4 + 2HOH
Lets start with the pH scale
pH is a logarithmic function based on the [H+]
The first step in pulling it all together is knowing the
Ion-Product Constant
for Water KW
The product of the concentrations of the
hydrogen ions and hydroxide ions in water
is KW and equals 1.0 X 10-14 (mol/L)2
KW = [H+] [OH-] = 1.0 X 10-14 (mol/L)2
[H+] = 1.0 X 10-7 mol/L [OH-] = 1.0 X 10-7 mol/L
Knowing Kw and the concentration of one of
the variables, we can determine the other!
Go to the WS
Calculating pH
Keeping in mind that pH is a logarithmic
function, we can calculate the pH using
the following equation.
pH = -log [H+]
Try these! Determine the pH.
Get your calculators out!!
1.
2.
3.
4.
5.
6.
[H+]= 1.0 x 10-7
[H+]= 1.0 x 10-5
[H+]= 1.0 x 10-9
[H+]= 2.5 x 10-9
[H+]= 1.6 x 10-5
[H+]= 3.7 x 10-9
How did you do?
1.
2.
3.
4.
5.
6.
[H+]= 1.0 x 10-7
[H+]= 1.0 x 10-5
[H+]= 1.0 x 10-9
[H+]= 2.5 x 10-9
[H+]= 1.6 x 10-5
[H+]= 3.7 x 10-9
pH= 7
pH= 5
pH= 9
pH= 8.6
pH= 4.8
pH= 8.4
What is pOH
pOH is a logarithmic function of the [OH-].
It works exactly the same as pH.
pOH = -log[OH-]
What is the relationship
between pH and pOH??
pH + pOH = 14
Yea!
Calculations
5. Columns 7-8 are the calculations we
learned on Friday.
6. Columns 9 and 10- Concentration is in
mol/L. Calculate how many moles in 2L
of solution.
Adding Acid to Water
HCl  H+ (aq) + Cl- (aq)
The acid adds more H+ increasing the [H+] in
the water. Therefore in any acid solution
the [H+] will be greater than the [OH-].
[H+] > 1.0 X 10 -7 mol/L
[H+] > 0.0000001 mol/L
Adding Base to Water
NaOH  Na+ (aq) + OH- (aq)
The base adds more OH- increasing the
[OH-] in the water. Therefore in any basic
solution the [OH-] will be greater than the
[H+].
[H+] < 1.0 X 10 -7 mol/L
[H+] < 0.0000001 mol/L
pH Scale
The pH of a solution is the negative
logarithm of the hydrogen-ion
concentration.
pH = -log [H+]
Neutral
Acidic
Basic
pH = 7
pH < 7
pH > 7
[H+] = 1.0 X 10 -7 mol/L
[H+] > 1.0 X 10 -7 mol/L
[H+] < 1.0 X 10 -7 mol/L
pH Scale
Indicator
A substance that “indicates” the pH of a
solution by changing color.
Red Litmus Paper
Blue Litmus Paper
Universal Indicator Paper
Red Cabbage Juice
Household pH Lab
You will be testing the pH of many solutions
that you use every day.
1. What do you think?
2. Cabbage Juice- 10 mL juice, add a few drops
of sample.
2. Litmus Paper– Use blue and red!
(example: Red turns Blue)
3. Universal pH paper- record color and
approximate pH.
4. Actual pH- from meter (I will give
you these).
Arrhenius Definition
An acid is a compound that produces
hydrogen ions (H+) when dissolved in
water.
A base is a compound that produces
hydroxide ions (OH-) when dissolved in
water.