Acids & Bases
Guided Notes
Page 1
Acids and Bases - Describing Acids and Bases
Mini-Project
Work with a partner. Organize the following formulas into two groups with five formulas in
each group: HNO3, NaOH, H2SO4, H2CO3, Ca(OH)2, KOH, H8PO4, Mg(OH)2, NH3, H2O
Group1
Group 2
Group One is ________.
Group Two are _________.
Where do NH3 and H2O fit? Why or Why Not?

______________ Models
o A model is a way to ____________ __________ or ____________ things that can’t be
seen.
o There are ___ common models
o We will learn 2

_________ Model (Oldest, most easily understood)

_____________ Model
Historical views on acids
The Bronsted-Lowry concept

_________ (e.g. H2SO4) was originally thought to cause acidic ________. Later, _________
was implicated, but it was still not clear why ________ was neutral.

__________ made the revolutionary suggestion that some solutions contain ________ & that
acids produce __________ ____________ ions in solution.

The more recent ____________ concept is that acids are _______ _________ donors and
_________ are proton ___________
__________ Model of Acids/Bases
o Substance is an _______ if it contains ______ and _____ causes ______ ____ to form in
solution
o Dissociation means to ________ ________
Acids & Bases

Guided Notes
Page 2
Substance is a ______ if it contains a _________ and dissociates to produce ____________
______ in solution
Arrhenius Model
 ACIDS
Are Always _____________ in solution
Taste _____________ (lemon, vinegar)
React with ____________ to (____________)
React with ____________ (makes bubbles of CO2)
Turns blue litmus ____________
In Water forms _____________ ION (or ______________ ion)
 BASES
Are ALWAYS _____________ in solution
Taste _________ (soap, tonic water)
Feel __________ (soap)
Turns Red Litmus __________
React with _________ to make water
Why are Some Solutions Acid & Others Base?

Acid solutions contain ________ ____ ions than ____ ions.

Not _______ OH- ions

Base solutions contain more _______ ions than _______ions.

Not ________ H+ ions

Water is the _________ for Acid/Base and is defined as __________

Water has ________ amounts of H+ and OH- ions (__________)
Bronsted-Lowry Model

Acid is a ________ (hydrogen ion) _________

Base is a ________ (hydrogen ion) _________

This is a ____________ definition than Arrhenius model because there are substances that cause
donation or reception ________ having hydrogen in them.

Which items from our list fit this definition but not Arrhenius? _______ and ________
Example

When an _______ dissolves in water, it donates an ______ ion to a ______ molecule forming
H3O+ (hydronium ion).
Acids & Bases

Guided Notes
Page 3
The ________ molecule acts as a Bronsted-Lowry ________and accepts the
o
H+
ion
HX + H2O ⇄ H3O+ + X-

____________ _________ = species produced when a base accepts a hydrogen ion from an acid

_____________ _________ = species produces when an acid donates a hydrogen ion to a base

Conjugate base _______ = ____ substances related to each other by _______ and __________ a
single hydrogen ion

In Bronsted-Lowry Model, every ________ and every ________ must have a corresponding
conjugate __________ or conjugate ___________.

A conjugate Base is an ________ that is _________ a ___________ ion.

A conjugate acid is a __________ that has an ____________ ___________ ion.

The ________ becomes the conjugate __________

The _________ becomes the conjugate __________.
Conjugate Acid/Base Practice problems
HC2H3O2(aq) +
H2O(l)
_____________
_________
OH –(aq) +
HCO3–(aq)
_____________
_________
HF(aq)
+
_____________
CO32–(aq) +
_____________
H3PO4(aq) +
_____________
SO32–(aq)

C2H3O2–(aq)
______________


HC2H3O2(aq) 
_________
_________
CO32–(aq)

F–(aq)
+
+
H3O+(aq)
__________
______________
_________
OCl –(aq)
+
H2O(l)
__________
HSO3–(aq)
______________
__________
C2H3O2–(aq) +
HCO3–(aq)
______________
__________
H2PO4–(aq)
______________
+
HOCl(aq)
__________
Acids & Bases
Guided Notes
Amphoteric = substances like water that can act like _________ an _______ or a _______
Monoprotic and Polyprotic Acids
___________ – acids based on formula that can donate only one hydrogen ions
CH3COOH + H2O ⇄ H3O+ + CH3COO____________ – acids that can donate multiple hydrogen ions
H3PO4 + H2O ⇄ H3O+ + H2PO4+
H2PO4+ + H2O ⇄ H3O+ + HPO4+2
HPO4+2 + H2O ⇄ H3O+ + PO4+3
________________ = oxides that can become acids or bases by adding elements contained in water
Acid Rain
Acid rain comes from rain collecting _____________from the air to create acids:
Carbon Dioxide = __________ acid
Sulfur oxides = ___________ or ____________ acid
Nitrogen oxides = _________ acid
Damages ___________, _________, kills__________, kills __________
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Acids & Bases
Guided Notes
Page 5
Acids and Bases in Solution
Chapter 19.2
Acid/Base Strength
In strong acids, almost all molecules ionize.
In weak acids, fewer molecules ionize.
Conjugate Pairs Strength
If an acid is a strong acid, its conjugate pair base is a weak base
Why?
If HX is strong acid, it ionizes completely.
The conjugate base must be a weak base because it has a greater attraction to the H+ than HX
The reaction equilibrium lies far to the right of the equation.
Conjugate Pair Strength
For a weak acid, the equation equilibrium lies to the right (reactant side)
Conjugate base (Y-) has a stronger attraction for the H+ ion than the base H2O
HY + H2O
H3O+ + Y-
Acid Ionization Constants
An “ionization constant” is the tendency of an item to make ions in solution.
Higher the constant, the higher the amount of ions.
Acid ionization constant is value of the equilibrium constant expression for a weak acid
Value Ka indicates whether reactants or products are favored at equilibrium
Weak acids have low Ka values
Acid Ionization Constants
Base Ionization Constant
Same Basic Principle as Acid
Measures OH- concentrations
pH Scale
Chapter 19.3
Ionization Constant for Water
The ionization constant for water is:
1.0 x 10-14
[Ka][Kb]
= [1.0x10-7] [1.0 x 10-7]
Acids & Bases
Experiments show that the product of
Guided Notes
[H+]
and
[OH-]
always equals 1.0 x
Page 6
10-14
at 298°C
pH scale is a way of showing this relationship of ionization constants
The pH Scale
pH stands for ‘per Hydrion’
Low pH is Acid
High pH is base
Water is neutral (7.0)
pH
There are many ways to consider acids and bases. One of these is pH.
[H+] is critical in many chemical reactions.
A quick method of denoting [H+] is via pH.
By definition pH = – log [H+], [H+] = 10-pH
The pH scale, similar to the Richter scale, describes a wide range of values
An earthquake of “6” is 10 as violent as a “5”
Thus, the pH scale condenses possible values of [H+] to a 14 point scale (fig. 2, p370)
Also, it is easier to say pH = 7 vs. [H+] = 1 x 10–7
pH
pH = -log [H+]
[H+] = 10-pH
pOH = -log [OH-]
pH + pOH = 14
Calculations with pH
Q: What is the pH if [H+]= 6.3 x 10–5?
pH = – log [H+]
‘(-)’, ‘log’, ‘6.3’, ’10x’, ‘(-)’, ‘5’, ‘)”, ‘)”, ‘ENTER’)
Calculating pH from Strong Acid Solutions
Strong acids are 100% ionized
For monoprotic acids, concentration of the acid IS the concentration of the H+ ion
Use Acid concentration as substitute for H+ ion concentration.
Use Base concentration as substitute for OH- concentration
Calculating pH from Strong Acid Solutions
Example: What is the pH of a 0.1M solution of HCl?
0.1 M HCl = 1 x 10-1 M
Calculate pH = 1
Acids & Bases
Guided Notes
Example: What is pH of solution that is 7.5 x
10-4
Page 7
M Ca(OH)2?
(7..5 x 10-4) x 2 = 1.5 x 10-3M
There are 2 OH- ions per molecule
Calculate pOH = -log[OH-]
= 2.8
pH = 14-2.8 = 11.2
Calculating Molarity from pH
Example: what is the molarity of an acid solution with a pH of 2.37?
[H+] = 10-pH
[H+] = 10-2.37 = 4.27 x 10-3 M
Neutralization
Chapter 15.4
Acid-Base Reactions
Neutralization reaction is a reaction between an acid and a base
Makes Water + Salt
Solution becomes Neutral (not acid or base)
Acid-Base Reactions
Mg(OH)2 + 2 HCl → MgCl2 + 2H2O
Note:
Cation from base (Mg) is combined with anion from acid (Cl)
The salt is MgCl2
The H+ and OH- always combine to form water
Acid-Base Titration
Acid/Base Titration is the stoichiometry of acid/base reactions.
Titration is a method for determining the concentration of a solution by using another solution of
known concentration
Uses an INDICATOR to show when the acid/base reaction is complete (neutral)
Indicator is a chemical that changes color as determined by acid or base conditions
There are many indicators with different pH points.
Acid/Base Titration Curve
pH Indicators
Calculating Molarity from Titration
Write the balanced equation
Acids & Bases
Guided Notes
Page 8
Calculate the number of moles used in the ‘known’ solution
Use the mole ratio from the balanced equation to calculate moles of reactant in the ‘unknown’
solution
Calculate the molarity of the ‘unknown’ solution based on moles used and liters used.
Salt Hydrolysis
When you put salts in water, the resulting solution can be either acid, base, or neutral
Salts will dissolve to form ions
The anions will accept hydrogens from water
The cations will accept hydroxides from water
Which way it goes depends upon the strength of the conjugate acids/bases
If conjugate acid is strong, it will be acid
If conjugate base is strong, it will be base
If both are strong, it will be neutral
What are Buffers?
Buffers are solutions that resist changes in pH when limited amounts of acid or base are added.
Buffer is a weak acid and its conjugate base or a weak base and it’s conjugate acid
Buffer can accept or donate Hydrogen ions and shift its equilibrium point left or right
Buffers have limits, but the work for a while
Heavily used in human body, especially blood
Acid Names
Binary or hydrohalic acids – HF, HCl, HBr, HI, etc. “hydro____ic acid” are usually strong
acids
If name ends in ‘-ide’
Acid name will be “hydro ____ic acid”
HF and H2S are weak hydrohalic acid. Although the H-F bond is very polar, the bond is so strong
(due to the small F atom) that the acid does not completely ionize.
Acid Naming
Oxyacids – contain a polyatomic ion
Most common form (MCF) “ic” ending – strong acids (contain 2 oxygen per hydrogen)
If chemical name ends in “-ate”
Acid name will be “___IC Acid”
HNO3 – nitric
from nitrate
Acids & Bases
Guided Notes
H3PO4 - phosphoric
from phosphate
H2SO4 - sulfuric
from sulfate
HClO3 - chloric
from chlorate
Acids with 1 less oxygen than the MCF “ous” ending- weaker acids
Chemical name ends in “-ite”
Acid name is “___OUS Acid”
HNO2 – nitrous
from nitrite
H3PO3 - phosphorous
from phosphite
H2SO3 - sulfurous
from sulfite
HClO2 - chlorous from chlorite
c. Acids with 2 less oxygen than the MCF “hypo___ous” – very weak acids
HNO - hyponitrous
H3PO2 - hypophosphorus
HClO - hypochorous
d. Acids with 1 more oxygen than the MCF “per______ic” – very strong acids
HClO4 – perchloric acid
HNO4 - pernitric acid
Organic acids – have carboxyl group -COOH - usually weak acids
Acid names are based on the base organic name or common name
HC2H3O2 - acetic acid
C7H5COOH - benzoic acid
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