Ch. 20 Notes -- Acids and Bases
What makes something an acid?
Acid Properties:
sour
lemons
(1) tastes _______-_______________
metals
(2) corrosive to _________
H+ ] (or [ _____
H3O+ ] = “_______________”
hydronium
(3) contains [ ___
ions)
(4) proton ([ ___
Brønsted-Lowry Theory
H+ ]) __________-donor
Example: HCl + H2O 
______
Cl−
+
H
O
3
+ ______
Properties of Bases
What make something a base?
Base Properties: (…the opposite of acid properties)
bitter -- ___________
banana peel ,
(1) tastes ________
parsley, dark chocolate
(2) feels _____________
slippery
-- ________
soap
OH− ] ions
(3) contains [ _____
acceptor
(4) proton ([H+]) ______________-Brønsted-Lowry Theory
NH4+ + _______
OH−
Example: NH3 + H2O  ______
pH of food
Content Goal: Students will test pH to determine if household
substances are an acid or a base.
Language Goal: Students will show they know the material by filling
out the paper that will be completed in class today
Social Goal: Students will work together safely and will follow
instructions so that everyone has equal access to lab materials.
Safety
 No play fighting or any touching.
 Move around the room in numerical order.
 Please keep the beakers on the table. Do not move the
beakers to you, move to the beakers.
 Place used test strips into the waste beaker.
 Wash your hands after the lab.
Common Acids
Examples of Common Acids:
•
citrus juices, ___________,
aspirin
Pepsi, _________
stomach acid, battery
acid, _____________,
vinegar
______
DNA
•
Common Bases
Examples of Common Bases: milk of magnesia, ___________,
ammonia
antacid
baking
drain cleaner, soap, blood, ____________
tablets, ___________
________.
soda
•
Indicators
An indicator is a chemical that will change ___________
colors
when
placed in an acidic, basic or neutral environment.
Indicator Colors For Acids
•
•
•
•
red
litmus paper = _______
clear
phenolphthalein = ___________
red cabbage juice (universal indicator) = ________
red
methyl orange = _______
red
•
•
•
•
Indicator Colors for Bases
litmus paper = _______
blue
yellow
methyl orange = ____________
blue
red cabbage juice (universal indicator) =________
phenolphthalein = ______
pink
phenolphthalein
Acid
Base
Universal pH Paper : Indicator Colors
Neutral
Acidic
Basic
•
Acid Vocabulary
strong acid - readily ___________
dissociates to produce ______
many [H+] ions in
water
H2SO4
Examples: _________,
HCl
HNO3, _______
•
small
weak acid - produces a __________
amount of [H+] ions when in
water
H2CO3 lemon
juice
Examples: HC H O (vinegar) , _________,
_________
2
3
2
•
Base Vocabulary
strong base- readily __________
dissociate to produce ______
many [OH−] ions in
water
Examples: NaOH , ________
KOH
•
small amount of [OH−] ions when in
weak base- produces a __________
water
NH3 (ammonia); Mg(OH) (milk of magnesia)
Examples: _____
2
Other Vocabulary
•
•
_______________another term for basic solutions
Alkaline
Amphoteric
_______________a substance that can act as both an acid and a base
−
H
O
HCO
2
3
Examples: ___________
, ____________
Self-Ionization of Water
•
Pure water is _____________.
neutral
It can ionize itself to form OH− and
H3O+ ions in __________
small amounts.
H2O +
(or
•
H2O  H3O+ + OH−
H+
OH− )
H2O  _______
+ _______
green
The universal indicator color is ___________
in neutral solutions.
self-ionization of water
Measuring the Amount of H+ and OH− Ions in a Solution
•
•
_____
pH Scale- measures the _____________
concentration of [H+] ions in a solution
pOH Scale- measures the concentration of [ ____
OH− ] ions in a solution
_____
Formulas
pH = − (log [H+])
[H+] = 10−pH
[H+] x [OH−] = 1 x 10−14
•
pOH = −(log [OH−])
[OH−] = 10−pOH
pH + pOH = 14
With the pH scale, we have another way to define acids and bases:
below
Acids have a pH _________7.0
above
Bases have a pH _________7.0
=
Neutral pH ___7.0
pH Testing
Alkalinity Testing
Practice Problems:
1)
a) Calculate the pH of a 0.001 M HCl solution
[H+] = 0.001 M
So…pH = − (log 0.001 M)
pH = 3
b) What is the pOH of this solution?
pH + pOH = 14
So…14 − 3 = pOH
pOH = 11
c) What is the concentration of [OH−] ions in the solution?
[OH−] = 10−pOH
2)
[OH−] = 10−11 Molar or 1 x 10−11 M
a) Calculate the pOH of a NaOH solution that has a pH of 8.50
pH + pOH = 14
So…14 − 8.5 = pOH
pOH = 5.5
b) What is the [OH−] of this solution?
[OH−] = 10−pOH
[OH−] = 10−5.5 Molar or 3.16 x 10−6 M
c) What is the concentration of [H+] ions in the solution?
[H+] = 10−pH [H+] = 10−8.5 Molar or 3.16 x 10−9 M
Neutralization Reactions
salt
When an acid and base are mixed, the reaction produces _______
water
and ___________.
•
•
If the initial concentrations and volumes of the reactants are equal,
neutral
the products will be ____________...
(pH= 7.0)
double
All neutralization reactions are ___________
replacement
reactions.
H2O
HX + M(OH)  ______
MX
+ ______
(“Salt”)
•
•
•
•
•
Titration
Mixing an acid with a base to
determine a __________________
concentration
is called “titration.”
An ____________
indicator is used to
determine when neutralization has
occurred.
Standard
________________
Solution - the
solution of known concentration
End _________
Point - the point of
______
neutralization when titrating
end point, the moles of
At the ______
[H+] ions = moles of [OH−] ions.
Determining the Concentration of an Acid (or Base) by Titration
(Macid)x(Vacid) = (Mbase)x(Vbase)
Practice Problems:
(1) A 25 mL solution of HNO3 is neutralized by 18 mL of 1.0 M
NaOH standard solution using phenolphthalein as an indicator.
What is the concentration of the HNO3 solution?
( Macid ) x ( 25 mL ) = ( 1.0 M ) x ( 18 mL )
Macid = 0.72 Molar
(2) How many mL of 2.0 M KOH will it take to neutralize 55 mL of
a 0.76 M HCl standard solution?
(0.76 M ) x ( 55 mL ) = ( 2.0 M ) x ( Vbase )
Vbase = 20.9 mL