Acids and Bases for Chapter Test

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Acids & Bases
Acids and Bases
OBJECTIVES
1- Identify the physical and chemical behaviors of acids and bases.
2-Define acids and bases according to the Arrhenius, and Bronsted-Lowry
theories.
3- Describe neutrality and relative acidity and alkalinity in terms of pH
measured using Universal Indicator paper.
4- Relate hydrogen ion concentrations to the pH scale and to acidic, basic,
and neutral solutions.
5- Distinguish between strong and weak acids and bases in terms of the
extent of dissociation, reaction with water and electrical conductivity.
6- Describe the characteristic properties of acids as reactions with metals,
bases, carbonates and effect on litmus and methyl orange.
7- Describe the characteristic properties of bases as reactions with acids
and with ammonium salts and effect on litmus and methyl orange.
Gloves must be worn all the time
Corrosive
Corrosive
Gloves must be worn all the time
Several types of acids and where they
are found:
• Hydrochloric acid:
Stomach acid – Sour taste
• Acetic acid:
An ingredient in vinegar
• Citric acid:
Citrus fruit like: Lemons, oranges and grapefruit.
• Lactic acid:
Sour milk, sour cream, yogurt, …
Several types of bases and how they
are used:
• Ammonia: (NH3)
Used in household cleaning materials and in fertilizers
• Calcium hydroxide: ( Ca(OH)2)
It helps to neutralize acidic soil
• Sodium hydroxide: (NaOH)
One of the strongest bases, used in oven and drain
cleaners.
• From the vinegar in your kitchen cabinet to the
soap in your shower, acids and bases are
everywhere!
• But what does it mean to say that something is
acidic or basic?
 In order to answer this question, we need to
examine some of the theories describing acids and
bases.
Arrhenius , Bronsted-Lowry, and Lewis
Theories
Self-Ionization of Water
Acids - Arrhenius definition
• An acid is any substance that, when added to water, increases the
hydronium ion (H3O+)
+
HCl H + Cl
Acids - Arrhenius definition
• A strong acid ionizes completely in a solvent
HNO3 + H2O  H+ + NO3• A weak acid releases few hydrogen ions in aqueous solution
HOCl + H2O  H3O+ + ClO-
https://www.youtube.com/watch?v=DupXDD87oHc
Practice
Which of the following is a weak acid?
A. HCl + H2O  H3O+ + Cl-
B. CH3COOH + H2O  H3O+ + CH3COOC. H2SO4 + H2O  H3O+ + HSO4-
D. HBr + H2O  H3O+ + Br-
Bases – Arrhenius definition
• A base is any substance that, when added to water, increases the
hydroxide ion (OH-)
Practice
1. What ion is characteristic of aqueous solutions of all acids?
2. Complete the following equations
A. HBr + _______  _______ + BrB. KOH + _______  OH- + _______
C. H2SO3 + H2 O  H3O+ + _______
Drawbacks of Arrhenius Definition
• Limited to aqueous solutions only
• E.g HCl should be considered an acid in aqueous or gaseous form
• Cannot classify substances that can act both as an acid and a base
Acid – Brønsted-Lowry
• A substance that donates a proton (H+) to another substance
• All Arrhenius acids are Brønsted-Lowry acids
https://www.youtube.com/watch?v=ZiokqP0aZ1E
Base - Brønsted-Lowry
• A substance that accepts a proton (H+)
• All Arrhenius bases are Brønsted-Lowry bases
Donates an H+
NH3 + HCl  NH4+ + Cl-
Accepts an H+
Conjugate Acids and Bases
https://www.youtube.com/watch?v=ZiokqP0aZ1E
Conjugate Acids and Bases
Conjugate Acids and Bases
Practice: identify the acid, base and their conjugates
H2SO4 + SO32-  HSO4- + HSO3-
Determine the acid, base, conjugate acid and conjugate base
for each of the following
Amphoteric Species
• Describes a substance that has the properties of an acid and also a
base
HCO3- + NH3  CO32- + NH4+
HCO3- + H3O+  H2CO3 + H2O
Strength of Acids and Bases
• A strong acid or base ionizes completely in a solvent
HCl  H+ + Cl• A weak acid or base releases few ions in aqueous solution
CHCOOH + H2O  CHCOO- + H3O+
Practice
• Compare a strong, dilute acid with a weak, concentrated acid
• Identify the conjugate acid base pair:
NH3 + H2O  OH- + NH4+
H2SO4 + SO32-  HSO4- + HSO3• Define amphoteric and give one example
• Compare bronsted-lowry definition with Arrhenius definition of an
acid and base
Common Strong Acids and Bases
Common Weak Acids and Bases
Reactions of Acids
1.
2.
3.
4.
5.
Metals
Metal Oxides/Metal Hydroxides
Carbonates
Litmus
Methyl Orange
Reaction of Metals with Acids
Metal + Acid
Salt + Hydrogen
For example
2HCl(aq) + Mg(s)
MgCl2(aq) + H2(g)
Hydrochloric + Magnesium
Acid
Magnesium + Hydrogen
Chloride
Metal Reactivity Series
To react with an
acid the metal
needs to be higher
than hydrogen in
the reactivity series.
Reactions of Acids - Metals
• E.g. Complete the following reactions:
Zn + H2SO4  ________ + ________
Na + HCl  _________ + ________
Salts from Acids
Remember:
Hydrochloric acid (HCl) makes chlorides (Cl-).
Sulfuric acid H2SO4 makes sulfates (SO42-)
Nitric acid (HNO3) makes nitrates (NO3-)
Practice
1.
2.
3.
4.
5.
6.
Mg + HCl 
H2SO4 + Fe 
HNO3 + K 
Na + CH3COOH 
Ca + HF 
HBr + Fe 
Reactions of Acids – Metal Oxides/Metal
Hydroxides
Metal Oxide + Acid  Water + Metal Salt
Metal Hydroxide + Acid  Water + Metal Salt
• E.g. Complete the following reactions:
NaOH + H2SO4  ________ + ________
KOH + HCl  _________ + ________
CaO + HNO3  _______ + ________
Practice
1. Ca(OH)2 + HCl 
2. H2SO4 + KOH 
3. HNO3 + FeO 
Reactions of Acids - Carbonates
Metal Carbonate + Acid  Carbon Dioxide + Metal Salt + Water
• E.g. Complete the following reactions:
MgCO3 + H2SO4  ________ + ________
ZnCO3 + HCl  _________ + ________
Practice
1. Na2CO3 + HCl 
2. H2SO4 + (NH4)2CO3
3. HNO3 + CuCO3
Reactions with Acids - Indicators
• Litmus – Turns blue Litmus red
• Methyl Orange – turns from
orange to pinky red
Reactions of Bases
1. Ammonium Salts
2. Litmus
3. Methyl Orange
Reactions of Bases – Ammonium Salts
Ammonium Salt + Base  Water + Metal Salt + NH3
• E.g. Complete the following reactions:
NH4Cl + NaOH  ________ + ________
NH4Br + Ca(OH)2  _________ + ________
Practice
1. Na2CO3 + HCl 
2. H2SO4 + (NH4)2CO3
3. HNO3 + CuCO3
Reactions with Bases - Indicators
• Litmus – Turns red Litmus blue
• Methyl Orange – turns from
orange to yellow
Practice – Write a word equation and
balanced symbol equation for:
• The reaction of copper (II) oxide and sulfuric acid.
• The reaction of zinc and hydrochloric acid.
• The reaction of magnesium and nitric acid.
• The reaction of calcium oxide and sulfuric acid.
Summary
Acid
Base
Litmus
Blue  Red
Red  Blue
Methyl Orange
Orange  Yellow
Orange  Pink
Carbonates
Metal Carbonate + Acid  CO2
+ Salt + H2O
Oxides
Metal Oxide + Acid  H2O + Salt
Hydroxides
Metal Hydroxide + Acid  H2O
+ Salt
Ammonium Salt + Base  H2O +
Metal Salt + NH3
Ammonium Salts
Metals
Metal + Acid  Salt + H2
Electrical Conductivity and Strength of Acid
and Base
• Acids and bases are electrolytes
• The more a substance dissociates, the more electrically conductive it
becomes
Electrical Conductivity and Strength of Acid
and Base
• A strong acid or base completely
dissociates
• Strong electrolytes
• More ions in solution
• Therefore more electrical
conductivity
Electrical Conductivity and Strength of Acid
and Base
• A weak acid or base partially
dissociates
• Weak electrolytes
• Less ions in solution
• Less electrical conductivity
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