Acids and Bases
Acids and Bases Definitions
1. Demo – Intro to Acids and Bases
a. What is an indicator? Chemical that changes color for an acid or base
RED in the presence of acid.
b. Universal indicator changes from green to _____
BLUE in the presence of base.
c. Universal indicator changes from green to _____
d. What do acids and bases make when they neutralize each other?
Salt
Water
__________
& __________
Acids and Bases Definitions
1. Review Naming Acids and Bases from formula
Carbonic Acid
a. H2CO3
________________
b. Ca(OH)2 ________________
Calcium Hydroxide
c. H3N
________________
Hydronitric Acid
d. HC2H3O2 ________________
Acetic Acid
• Review Writing formulas from names:
HF
a. Hydrofluoric acid
________
Cu(OH)2
b. Copper (II) hydroxide
________
Mg(OH)2
c. Magnesium hydroxide ________
H2SO3
d. Sulfurous acid
________
e. Phosphoric acid
________
H3PO4
Arrhenius Model of Acids and Bases
1. What are acids and bases?
Arrhenius model (1887)
Acid – Contains H+ and produces H+ in solution
Base – Contains OH- and produces OH- in solution
Ex: HCl(g)

H+(aq) + Cl –(aq)
Ex: NaOH(s)  Na+(aq) + OH-(aq)
** What was the problem with Arrhenius’s model?
Ex. NH3 + H2O  NH4+ + OHAmmonia (base)
Arrhenius didn’t include all bases
__________________________________________
H+
Cl-
Cl-
H+
Na+
OH-
OH-
Na+
Acids and bases
both dissociate
into ions when
dissolved in
water
Bronstead Lowry Model of Acids and Bases
Bronsted-Lowry Model
(includes ALL Bases – based on how acids and bases act)
Acid – Donates H+
Base – Accepts H+
Look at the products!
A
B
HX(aq)
+
H2O(l)   H3O+(aq) + X-(aq)
Ex:
A
HF
Ex.
B
NH3(aq)
+
B
H2O   H3O+
+
+
F–
A
H2O(l)   NH4+(aq) + OH-(aq)
Summary
Yes
Are all Arrhenius acids also Bronsted-Lowry acids? ___
Donates H+
Why? __________________
Yes
Are all Bronsted-Lowry acids also Arrhenius acids? ____
Contains H+
Why? __________________
Yes
Are all Arrhenius bases also Bronstead-Lowry bases? __
+
Accepts H
Why? ___________________
No
Are all Bronstead-Lowry bases also Arrhenius bases? ____
Some don’t contain OH- (like NH3)
Why? _______________________________
Stations Notes
Characteristics
Acids
Bases
Taste
Reaction with metals
Conductivity
Texture
More H+ or OH- ?
pH range
Indicators:
a. Litmus paper
b. Phenolphthalein
(base indicator)
c. Universal Indicator
a.Red Litmus –
Blue Litmus b.
c.
a.Red Litmus –
Blue Litmus b.
c.
Examples - Acids and bases
are common in both the
laboratory and the home:
Laboratory:
Laboratory:
Home:
Home:
Stations Notes
Characteristics
Taste
Reaction with metals
Conductivity
Texture
More H+ or OH- ?
pH range
Acids
Bases
Sour
Yes
Yes
Like Water
More H+
Less than 7
Bitter
No
Yes
Slippery
More OHMore than 7
Indicators:
a. Litmus paper
b. Phenolphthalein
(base indicator)
c. Universal Indicator
a.Red Litmus – Stays Red a.Red Litmus – Turns Blue
Blue Litmus - Turns Red
Blue Litmus – Stays Blue
b. No change
b. Turns hot pink
c. Red
c. Blue
Examples - Acids and bases
are common in both the
laboratory and the home:
Laboratory:
Laboratory:
Home:
Home:
Acid-Base Reactions
DEMO: MOM Rainbow
DEMO (MOM rainbow) – Neutralization reaction of an Antacid.
When do we take antacids? Acid Reflux
How do antacids work in your stomach? They neutralize the stomach acid
What is the formula of Milk of Magnesia? Mg(OH)2
Base
What type of substance is an antacid? ________How
do you know? It can neutralize the acid
Give another example of an antacid.
Why is it called “antacid”? It is anti – acid, does the opposite
What is the scientific name for stomach acid? Hydrochliric Acid
What is the formula? HCl
Write the equation for magnesium hydroxide (antacid) neutralizing a stomach acid.
Predict and name the products. Balance the equation:
HCl
Mg(OH)2
MgCl2 + ________
H2O
_________
+ ________
_________
Product Names: Magnesium Chloride and Water
• Salt - Ionic compound made up a cation from a metal and an
anion from an non-metal
• What type of reaction is acid-base neutralization?
Double Replacement Reaction
Acid Base Neutralization Reaction
• An acid base neutralization reaction is a double replacement
reaction that results in a salt and water (pH = 7)
Ex: Hydrochloric acid is neutralized by calcium hydroxide.
CaCl2
H 2O
HCl + Ca(OH)2  ________
+ _________
Product Names: Calcium Chloride and Water
Now its time for you to work on the
practice! Use your notes to help you
answer the questions!
pH Scale
pH Scale
Molarity (M) of the hydrogen ions.
[H+] represents the molar concentration {____________}
[H+] 1x 100M
pH scale:
0
1 x 10-14M
7
14
Tenfold
**A change of one pH unit represents a ____________change
in ion concentration.
Potential of Hydrogen
What does pH stand for? ______________________
10 times stronger than a pH of 5
A pH of 4 is ___________________
times weaker than a pH of 5
A pH of 10 is 100,000
_________________________
[H+] = [OH-] neutral (pH = 7)
[H+] < [OH-] base (pH above 7)
[H+] > [OH-] acid (pH below 7)
To find pH if you know the Hydrogen ion
concentration, use the following formula:
pH = -log[ H+ ]
Calculate the pH of each solution:
Solution 1 has a [H+] equal to 1x10-7M
pH = -log(1E-7)
pH = 7
Answer: ________________
Is the solution an Acid , Base , or Neutral ?
Solution 2 has a [H+] equal to 3.6 x 10-9M
pH = -log(3.6E-9)
pH = 8.44
Answer: ________________
Is the solution an Acid , Base , or Neutral ?
To find the H+ concentration when given the pH
use:
[H+] = 2nd log (-pH)
Calculate the [H+] (concentration) for each solution.
Solution 1 has a pH of 4.0
-4 M
1
x
10
Answer:
________________
[H+] = 2nd log (-4)
Is the solution an Acid , Base , or Neutral ?
Solution 2 has a pH of 11.5
[H+] = 2nd log (-11.5)
-12 M
3.16
x
10
Answer: ________________
Is the solution an Acid , Base , or Neutral ?
To find hydroxide concentration (or the [H+] if
not given the pH). Use the following formula:
Kw = [H+][OH-] = 1 x 10-14
At 298K, the [OH-] is 1.0 x 10-11M. Find the [H+] in the solution and
determine whether the solution is acidic, basic, or neutral.
Formula: Kw = [H+][OH-]
Work:
1E-14 = [H+](1E-11)
-3 M
.001
M
or
1
x
10
Answer: __________________
Is the solution an Acid , Base , or Neutral ?
To find pH if you know the hydroxide ion
concentration. Use the following formulas:
Kw = [H+][OH-] = 1 x 10-14 &
pH = -log[ H+ ]
At 298K, the [OH-] is 1.0 x 10-10M. Find the pH of the solution and
determine whether the solution is acidic, basic, or neutral.
Formulas: Kw = [H+][OH-] = 1 x 10-14
Work:
1 x 10-14 = [H+](1E-10)
&
pH = -log[ H+ ]
[H+] = 1E-4 M
pH = -log [ H+ ]
pH = -log(1E-4 M )
Answer: _______
pH = 4
Is the solution an Acid , Base , or Neutral ?
Strengths of Acids and Bases
Acid Strength
Acids that dissociate into ions (ionize) completely in aqueous
STRONG acids; produce the __________
maximum
solutions are called _________
good
number of ions, so they are______conductors
of electricity and
therefore strong acids are STRONG
_______ electrolytes.
Examples: HCl, HNO3, HI, H2SO4
partially ionize in aqueous solutions are called
Acids that ___________
WEAK acids; cannot conduct electricity as efficiently and
________
WEAK electrolytes.
therefore, weak acids are ______
Examples: HC2H3O2, HF, HCN, H2CO3
Base Strength
completely
1. Bases that ionize ____________in
aqueous solutions into
hydroxide ions are called _________
STRONG bases.
metal ions and __________
OH- to be a strong base.
Base must contain _____
Examples: NaOH, KOH, RbOH, CsOH, Ca(OH)2
partially
2. Bases that ____________
ionize in solutions are called
WEAK
________
bases.
Examples: NH3, CH3NH2 (methylamine)
Summary
100 into ions in solution.
• Strong acids and bases dissociate ____%
1 into ions in
• Weak acids and bases dissociate about __%
solution.
Difference between Strength and Concentration
Concentration (dilute or concentrated) refers to the
amount
____________of
the acid or base molecules dissolved in a volume of
solution (molarity = M).
dissociation
Strength (weak or strong) refers to the degree of ____________,
ions
which means how easily the acid or base separates into _____.
Example: 0.6 M HCl or 6 M HC2H3O2
HC2H3O2
Which more concentrated?______
HC2H3O2
Which is stronger? _________
HCl How do you know? Strong Acid
Which acid has a higher pH?_____
Which acid has a lower pH? HC
________
2H3O2 How do you know? Weak Acid
The degrees of dissociation into ions for HCl
and HC2H3O2
100% dissociation (ionization)
1% dissociation (ionization)
No HCl molecules, just ions
Both, HC2O3H2 molecules & ions are in
a solution.
Molecules < Ions
Molecules > Ions