Chapter 18
Acids and Bases
Rainbow Connection
#2
Ch. 18- Acids and Bases
• Acids and bases have a central role in
chemistry
• They affect our daily life
• Uses: manufacturing processes,
environmental issues, functioning of our
bodies
• Acid/ Base Video
Properties of Acids
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Have pH  0-6
Tart or sour taste
Will conduct electricity
Cause indicators to change color (turns blue
litmus red)
• Reacts w/ metals (Mg,Zn) to form H2 gas
• Neutralize w/ a base forms a salt and H20
• Ex. Citrus foods, tomatoes, vinegar
Acid Formulas (memorize)
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HCl ( Hydrochloric Acid)
HNO3 (nitric acid)
H2SO4 (sulfuric acid)
H2CO3 (carbonic acid)
HC2H3O2 (acetic acid)
H3PO4 (phosphoric acid)
Properties of Bases
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Also known as alkaline
pH  8-14
Have a bitter taste, slippery feel
Causes indicators to change color (turns red
litmus blue)
• Conducts electricity
• Reacts w/ acid to neutralize  form a salt and
H2O
• Ex. Cleaning products, soap, baking soda
Acid/ Base Theories
• Definitions have changed over the years as
new information has been found
• Arrhenius Theory video
Arrhenius Theory (1887)
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Applies to a H2O solution
Svante Arrhenius (Swedish) saw that not
only do acids/ bases conduct electricity, they
ionize (or release charged particles) when
dissolved in water
Theory:
1. Acids- substance that ionize & produced (H+)
hydrogen ions in H2O
2. Bases- ionize to produce (OH-) hydroxide ions in
H2O
Ex. HCl  H+(aq) + Cl-(aq)
ACID
NaOH  Na+(aq) + OH-(aq)
BASE
Brønsted- Lowry Theory
(1923) (video)
• Working independently of each other,
Johannes Brønsted (Danish) and Thomas
Lowry (English) defined a theory that can be
used w/ all solvents not just H2O (they found
that substance lost or gained protons)
• Acid- in a chemical reaction, this is the
substance that loses or donates a proton (H+
ion)
• Base- substance that accepts or gains a
proton (H+ ion = proton)
• HCl
+
H2O 
H3O+ +
Cl-
Accepts proton (base)
Donates (loses) proton – (acid)
H3O+  hydronium ion (formed when H2O gains H+ ion)
• NH3
+
H2O 
NH4+ +
OH-
Accepts proton (base)
Donates (loses) proton – (acid)
Amphoteric – (H2O) acts as an acid or a base
(depending on the situation)
Conjugates
• The particles that are formed as products can
react again (reversible reaction), they behave
like acids and bases (we call these
conjugates)
• Conjugate video
• Conjugate Acid - Particle that forms after the
base accepts a proton (H+) from the acid
• Conjugate Base – particle that remains after a
proton (H+) has been released by the acid
Ex.
HNO3 + NaOH  H2O + NaNO3
(H-OH)
Acid
Base
Conjugate Base
Conjugate acid
Disappearing ink
Ex.
KOH +
HBr 
KBr +
Base
Acid
H2O
Conjugate Acid
Conjugate Base
Neutralization Reaction
• Occurs when an acid and a base react and
there is a complete removal of all of the H+
and OH- ions
• Water will be formed w/ a salt in this double
displacement reaction
• The solution will be neutral in pH
• Important in: neutralization of soil, antacids
Salt
• Crystalline compound composed of the
negative (non-metal) ion of the acid and the
positive (metallic ) ion of the base
• Salt examples: CaSO4 (plaster board), NaCl,
KCl, (NH4)2SO4 (fertilizer)
Examples of Neutralization
Reactions
• Sodium hydroxide + hydrochloric acid 
sodium chloride + water
• NaOH + HCl  NaCl + H2O (H-OH)
• Potassium hydroxide + sulfuric acid 
water + potassium sulfate
• KOH
2 KOH +
+
H2SO4  H- OH
H2SO4 
2 H-OH + K2SO4
+
K2SO4
• Aluminum hydroxide + acetic acid 
Titration
Titration
• Used for a convenient method to determine
the concentration or molarity of an acid or
base
• Uses 2 burets (long glass tubes used to
measure volume)- Buret + .05 ml
Definition
• Analytical method in which a standard solution
is used to determine the concentration of
another solution
• Standard solution- one in which the
concentration is known
Process
• Using a given amount of acid in a flask, add
phenolphthalein and titrate to the end point
with the base (making sure to mark down all
the volumes)
• The whole reaction is a neutralization reaction
• Use an indicator to see the endpoint in which
complete neutralization occurs (wait for
phenolphthalein stays light pink for 30 sec)
Endpoint
Past endpoint
Titration Process
Calculations
• Reminder: M= moles
•
liters
• So: Base (titrated soln) 
– Moles (base) = volume (base) x Molarity (base)
Acid (standard soln) 
Moles (acid) = volume (acid) x Molarity (acid)
• Look at balanced equation and find the moles
of the standard and the moles of the titrated
unknown (look at coefficients)
• Most times it is a 1:1 ratio
• 1 NaOH + 1 HCl  NaCl + H2O (H-OH)
• So:
1 mole (base) = 1 mole (acid)
• Therefore: MA VA = MBVB
Problem
• A titration of 15.00 ml of HCl, required 38.57
ml of a 0.152 M base NaOH. Calculate the
molarity of the HCl (acid).
• MA = ?
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MA VA = MBVB
MA = M BVB
VA
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MA = (.152M) (38.57 ml)
(15.00ml)
MA = .391 M
Titration Calculation
ID- A, B, CA, CB
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CaCO3 + HCl  CaCl2 + H2CO3
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KOH + H3PO4  K3PO4 + H2O
• phosphoric acid + calcium hydroxide
calcium phosphate + water
• HBr + Al(OH)3
• Sulfuric acid + potassium hydroxide 
Indicators
• Used to find out if things are acidic or basic
• Def: weak organic acids or bases whose
colors differ from the colors of their conjugate
acids or bases
acid
base
Needs of Indicators
• Solution being tested needs to be colorless
• You need to be able to distinguish the color
change
• Need several indicators to cover entire pH
range (0-14)
• Liquid solution
Indicator Examples
• Litmus  red turns blue = base, blue turns
red = acid
• Phenolphthalein hot pink > pH 10
• Bromothymol blue  blue= base (8),
Green= neutral, yellow = acid (6)
• Universal Indicator  Rainbow (all pH’s 4-10)
• (bromothymol blues)
How Chemists use Indicators
Ionization of H2O
• Pure water can self ionize, it also acts as an
acid or a base (amphoteric)
• So: H2O(aq)  H+(aq) + OH- (aq)
• Experiments have shown that the
concentration of [H+] = 1 X 10 –7M and [OH-]
= 1 x 10 –7 M in pure water
• [ ] means concentration
Ion Product Constant for water
•
Equilibrium expression from the
multiplication of the concentrations of the
products
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[H+] [OH-] =?
• (1 x 10 –7)(1 x 10 –7) = 1.0 x 10
1. [H+] [OH-] = 1.0 x 10 -14
-14
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If [H+] = 1.5 x 10 -6 M, what is the [OH-] = ?
[H+] [OH-] = 1.0 x 10 -14
(1.5 x 10 -6) [OH-] = 1.0 x 10 -14
[OH-] = 1.0 x 10 -14
1.5 x 10 -6
[OH- ] = 6.7 x 10-9 M
pH Concept (video)
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Acidity scale developed by Soren Sorenson
base on the “power of the hydrogen”
pH – measure of the hydrogen ion
concentration of the solution
– Equal to the negative logarithm of the hydrogen
ion concentration
2. pH = - log [H+]
Ex. [H+] = 1.5 x 10-8
pH= ?
Graphing Calc.
(-) log 1.5 (2nd) EE -8
Regular calc.
1.5 EE -8 log +/-
pH= 7.8
To go from pH to
[H+]concentration
3. [H+] = antilog (-pH)
Antilog = 10x key
• pH= 3.5
• [H+] = ?
[H+] = antilog (-pH)
[H+] = antilog (-3.5)
Graphing = 2nd log
-3.5
Regular
3.5 +/2nd log
(to put in sci.not. Use 2nd #5)
[H+] = 3.2 x 10 -4 M
pOH (hydroxide power)
4. pH + pOH =14
• pH= 8
• pOH = ?
8 + ? = 14
pOH= 6
5. pOH = - log [OH-]
6. [OH-] = antilog (-pOH)
• [H+] = 3.5 x 10 -7 M,
[OH-] = ?
• pH = 8.95 , [H+] = ?
• [OH-] = 5.65 x 10 -2 M,
pOH = ?
• pOH= 11.9, [H+] = ??
• Formula 1
• Formula 3
• Formula 5
• Formula 4, then 3 or
• Formula 6, then 1
Rosengarten acid and base video