Ch' 20 Notes Acids and Bases

1
Ch. 20 Notes -- Acids and Bases

• What makes something an acid?
• Acid Properties
• (1) tastes _______-- _______________
• (2) corrosive to _________
• (3) contains ___ (or _____
  _______________ ions)
• (4) proton ( ___ ) __________-- Brønsted-Lowry
  Theory
• Example HCl H2O ? ______ ______

sour
lemons
metals
H
H3O
hydronium
H
donor
H3O
Cl-
2

• Examples of Common Acids
• Pepsi, _________ juices, ___________, stomach
  acid, battery acid, _____________, ______
  

citrus
aspirin
vinegar
DNA
3
Acid Vocabulary

• monoprotic acid- contains ____ H ion in its
  formula
• Examples _______ , ________
• diprotic acid- contains _____ H ions in its
  formula
• Examples _______ , ________
• triprotic acid- contains _____ H ions in its
  formula
• Examples _______ , ________
• strong acid - readily ___________ to produce
  ______ H ions in water
• Examples _________, HNO3, _______
• weak acid - produces a __________ amount of H
  ions when in water
• Examples HC2H3O2 (vinegar) , _________,
  _________

1
HNO3
HCl
2
H2SO4
H2CO3
3
H3PO4
H3BO3
dissociate
many
H2SO4
HCl
small
H2CO3
lemon juice
4
Strong Acids vs. Weak Acids
5
Indicators

• An indicator is a chemical that will change
  ___________ when placed in an acidic, basic or
  neutral environment.
• Indicator Colors For Acids
• litmus paper _______
• phenolphthalein ___________
• red cabbage juice (universal indicator)
  ________
• methyl orange _______

colors
red
clear
red
red
6
pH Paper Indicator Colors
Neutral
Acidic
Basic
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Properties of Bases

• What make something a base?
• Base Properties (the opposite of acid
  properties)
• (1) tastes ________ -- ___________ peel ,
  parsley, dark chocolate
• (2) feels _____________ -- ________
• (3) contains _____ ions
• (4) proton (H) ______________-- Brønsted-Lowry
  Theory
• Example NH3 H2O ? ______ _______

bitter
banana
slippery
soap
OH-
acceptor
NH4
OH-
8
Indicator Colors for Bases

• litmus paper _______
• methyl orange ____________
• red cabbage juice (universal indicator)
  ________
• phenolphthalein ______

blue
yellow
blue
pink
phenolphthalein
Acid
Base
9
Common Bases

• Examples of Common Bases milk of magnesia,
  ___________, drain cleaner, soap, blood,
  ____________ tablets, ___________ ________.

ammonia
antacid
baking
soda
10
Strong Bases vs. Weak Bases

• strong base- readily __________ to produce
  ______ OH- ions in water
• Examples NaOH , ________
• weak base- produces a __________ amount of OH-
  ions when in water
• Examples _____ (ammonia) Mg(OH)2 (milk of
  magnesia)
• Other Vocabulary
• _______________- another term for basic
  solutions
• _______________- a substance that can act as both
  an acid and a base
• Examples ___________ , ____________

dissociate
many
KOH
small
NH3
Alkaline
Amphoteric
H2O
HCO3-
11
Conjugate Acid-Base Pairs

• Conjugate ______- substance formed when a
  _______ gains a H ion.
• Conjugate ______- substance formed when an
  ______ loses a H ion.
• Practice Problems Label the acid base on the
  left side of the reaction and the conjugate acid
  conjugate base on the right side.
• a) HCl H2O ? H3O Cl-
• ______ ______ ______
  ______
• b) NH3 H2O ? NH4 OH-
• _____ ______ ______
  ______

Acid
base
Base
acid
acid
base
C.A.
C.B.
base
acid
C.A.
C.B.
12
Self-Ionization of Water

• Pure water is _____________. It can ionize
  itself to form OH- and H3O ions in __________
  amounts.
• H2O H2O ? H3O OH-
• (or H2O ? _______ _______ )
• The universal indicator color is ___________ in
  neutral solutions.

neutral
small
H
OH-
green
self-ionization of water
13
Measuring the Amount of H and OH- Ions in a
Solution

• _____ Scale- measures the _____________ of H
  ions in a solution
• _____ Scale- measures the concentration of ____
  ions in a solution
• Formulas
• pH - (log H) pOH -(log OH-)
• H 10-pH OH- 10-pOH
• H x OH- 1 x 10-14 pH pOH 14
• With the pH scale, we have another way to define
  acids and bases
• Acids have a pH _________7.0
• Bases have a pH _________7.0
• Neutral pH ___7.0

pH
concentration
pOH
OH-
below
above

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15
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16
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• Practice Problems
• 1) a) Calculate the pH of a 0.001 M HCl
  solution
• b) What is the pOH of this solution?
• c) What is the concentration of OH- ions in
  the solution?
• 2) a) Calculate the pOH of a NaOH solution
  that has a pH of 8.50
• b) What is the OH- of this solution?
• c) What is the concentration of H ions in the
  solution?

H 0.001 M
SopH - (log 0.001 M)
pH 3
pH pOH 14
So14 - 3 pOH
pOH 11
OH- 10-pOH
OH- 10-11 Molar or 1 x 10-11 M
So14 - 8.5 pOH
pH pOH 14
pOH 5.5
OH- 10-5.5 Molar or 3.16 x 10-6 M
OH- 10-pOH
H 10-pH
H 10-8.5 Molar or 3.16 x 10-9 M
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Ch. 21 Notes -- Neutralization

• Neutralization Reactions
• When an acid and base are mixed, the reaction
  produces _______ and ___________.
• If the initial concentrations and volumes of the
  reactants are equal, the products will be
  ____________... (pH 7.0)
• All neutralization reactions are ___________
  replacement reactions.

salt
water
neutral
double
H2O
HX M(OH) ? ______ ______
MX
(Salt)
19
Titration

• Mixing an acid with a base to determine a
  __________________ is called titration.
• An ____________ is used to determine when
  neutralization has occurred.
• ________________ Solution - the solution of known
  concentration
• ______ _________ - the point of neutralization
  when titrating
• At the ______ point, the moles of H ions
  moles of OH- ions.

concentration
indicator
Standard
End Point
end
20

• Practice Problems
• (1) Complete the following neutralization
  reactions.
• HNO3 (aq) KOH (aq) ? _________
  __________
• HCl (aq) Ca(OH)2 (aq) ? __________
  ___________
• (2) How many moles of Ca(OH)2 will it take to
  neutralize 0.5 moles of HCl?
• 3) How many moles of HNO3 will it take to
  neutralize 3.0 moles of KOH?

KNO3
H2O
-1
2
CaCl2
H2O
2
2
1 mole Ca(OH)2
0.5 moles HCl
0.25 moles of Ca(OH)2
x

2 moles HCl
1 mole HNO3
3.0 moles KOH
3.0 moles of HNO3
x

1 mole KOH
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Determining the Concentration of an Acid (or
Base) by Titration

• (Macid)x(Vacid) (Mbase)x(Vbase)
• Practice Problems
• 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?
• (2) How many mL of 2.0 M KOH will it take to
  neutralize 55 mL of a 0.76 M HCl standard
  solution?

( ) x ( ) (
) x ( )
Macid
25 mL
1.0 M
18 mL
Macid 0.72 Molar
( ) x ( ) (
) x ( )
0.76 M
55 mL
2.0 M
Vbase
Vbase 20.9 mL