Chapter Four:
TYPES OF CHEMICAL
REACTIONS AND
SOLUTION
STOICHIOMETRY
講義
Assignment for Chapter 4
12,20,27,35,47,57,63,75,83,95,107.
Core Materials
• Chemical reactions in solution are very important in
everyday life.
• Water is a polar solvent that dissolves many ionic and
polar substances.
• Electrolytes
• Acids and bases: Arrhenius model, BrØnsted-Lowry model.
• Molarity
• Types of equations that describe solution reactions:
Formula equation; Complete ionic equation; Net ionic equation.
• Solubility rules
• Important types of solution reactions: Acid-base reactions;
Precipitation reactions; Oxidation-reduction reactions.
• Titrations: Stoichiometric(equivalence)point;Endpoint:
Oxidation-reduction reactions: Oxidation,
Reduction,Oxidizing agent,Reducing agent.
Chemical Impact
Arrhenius A Man with Solutions (p.132)
Science is a human endeavor, subject to frailties
and governed by personalities, politics, and prejudices.
One of the best illustrations of the often bumpy path of
The advancement of scientific knowledge is the story of
Swedish chemist Svante Arrhenius.
……
Such a setbakc could have ended his scientific career, but
Arrhenius was a crusader; he was determined to see his
theory thriumph. He promptly embarked on a political
campaign, enlisted the aid of several prominent scientists,
to get his theory accepted.
Ultimately, the ionic theory triumphed. Arrhenius’ fame
Spread, and honors heaped on him, culminating in the
Nobel Prize in chemistry in 1903. Not one to rest on his
laurels., Arrhenius turned to new fields, including astronomy,
He formulated a new theory that the solar system may have
Come into being through the collision of stars. His exceptional
Versatility led him to study the use of serums to fight disease,
Energy resources and conservation, and the origin of life.
Nature of Aqueous Solutions
• Solute – substance being dissolved
• Solvent – liquid water
• Electrolyte – substance that when
dissolved in water produces a solution that
can conduct electricity
4.2
Water, the Common Solvent
• One of the most important substances on
earth
• Can dissolve many different substances
• A polar molecule
4.1
Water, the Common Solvent, with many
uncommon properties
• One of the most important substances on
earth
• Can dissolve many different substances
• A polar molecule
Lowest density at 4 oC,
Ice is lighter than water,
Large specific heat,
Large vaporization and melting heats,
….
4.1
Figure 4.1
The Water
Molecule
Figure 4.2 Polar Water Molecules Interact
with the Positive and Negative Ions of a Salt
Assisting in the Dissolving Process
Dissolution of a Solid in a Liquid
4.1
Water can also dissolve many non-ionic
compounds
Figure 4.3a The Ethanol Molecule Contains
a Polar O-H Bond Similar to Those in the
Water Molecule
Figure 4.3b The Polar Water Molecule
Interacts Strongly with the Polar-O-H bond in
Ethanol
Figure 4.4a-c Electrical Conductivity of
Aqueous Solutions
Figure 4.5 NaCl Dissolves
Figure 4.6
HCl is
Completely
Ionized
Figure 4.7 An
Aqueous
Solution of
Sodium
Hydroxide
Figure 4.8
Acetic Acid
(HC2H3O2)
Figure 4.9
The
Reaction
of NH3 in
Water
Electrolytes
• Strong Electrolytes – conduct current very
efficiently (bulb shines brightly)
• Weak Electrolytes – conduct only a small
current (bulb glows dimly)
• Nonelectrolytes – no current flows (bulb
remains unlit)
4.2
Electrolyte Behavior
4.2
Chemical Reactions of Solutions
• We must know:
– Nature of the reaction
– Amounts of chemicals present in the solutions
4.3
Molarity
• Molarity (M) = moles of solute per volume
of solution in liters:
moles of solute
M  molarity 
liters of solution
6 moles of HCl
3 M HCl 
2 liters of solution
4.3
An Aqueous
Solution of
Co(NO3)2.
Concept Check
Which of the following solutions contains
the greatest number of ions?
a)
b)
c)
d)
400.0 mL of 0.10 M NaCl.
300.0 mL of 0.10 M CaCl2.
200.0 mL of 0.10 M FeCl3.
800.0 mL of 0.10 M sucrose.
4.3
Let’s Think About It
• Draw molecular level pictures showing
each solution. Think about relative
numbers of ions.
• How many moles of each ion are in each
solution?
4.3
Notice
The solution with the greatest number of
ions is not necessarily the one in which:
– the volume of the solution is the largest.
– the formula unit has the greatest number of
ions.
4.3
Dilution
• The process of adding water to a stock
solution to achieve the molarity desired for
a particular solution.
• Dilution with water does not alter the
numbers of moles of solute present.
• Moles of solute before dilution = moles of
solute after dilution
M1V1 = M2V2
4.3
Types of Chemical Reactions
• Precipitation Reactions
• Acid-Base Reactions
• Oxidation-Reduction Reactions
4.4
Precipitation Reaction
• A double displacement reaction in which a
solid forms and separates from the
solution.
– When ionic compounds dissolve in water, the
resulting solution contains the separated ions
– Precipitate – the solid that forms
4.5
Figure 4.17 Molecular-Level
Representations Illustrating the Reaction of
KCl (aq) with AgNO3 (aq) to Form AgCl (s)
Precipitation of Silver Chloride
KCl (aq) + AgNO3 (aq)  AgCl (s) + K+(aq) +NO3 – (aq)
Cl– (aq) + Ag+ (aq)  AgCl (s)
The Reaction of K2CrO4(aq) and
Ba(NO3)2(aq)
• Ba2+(aq) + CrO42–(aq) → BaCrO4(s)
solid BaCrO4 formed
4.5
Precipitates
• Soluble – solid dissolves in solution; (aq)
is used in reaction
• Insoluble – solid does not dissolve in
solution; (s) is used in reaction
• Insoluble and slightly soluble are often
used interchangeably
4.5
Simple Rules for Solubility
1.
2.
3.
4.
5.
6.
Most nitrate (NO3) salts are soluble.
Most alkali (group 1A) salts and NH4+ are soluble.
Most Cl, Br, and I salts are soluble (except Ag+, Pb2+,
Hg22+).
Most sulfate salts are soluble (except BaSO4, PbSO4,
Hg2SO4, CaSO4).
Most OH salts are only slightly soluble (NaOH, KOH
are soluble, Ba(OH)2, Ca(OH)2 are marginally soluble).
Most S2, CO32, CrO42, PO43 salts are only slightly
soluble.
4.5
Table 4.1 Simple Rules for the
Solubility of Salts in Water
Describing Reactions in Solution
• Formula Equation (Molecular Equation)
– Reactants and products as compounds
AgNO3(aq) + NaCl(aq)  AgCl(s) + NaNO3(aq)
• Complete Ionic Equation
– All strong electrolytes shown as ions
Ag+(aq) + NO3(aq) + Na+(aq) + Cl(aq) 
AgCl(s) + Na+(aq) + NO3(aq)
4.6
Describing Reactions in Solution
• Net Ionic Equation
– Show only components that actually react
Ag+(aq) + Cl(aq)  AgCl(s)
– Na+ and NO3 are spectator ions
4.6
Concept Check
You have two separate beakers with aqueous
solutions, one with 4 “units” of potassium sulfate
and one with 3 “units” of barium nitrate.
a) Draw molecular level diagrams of both
solutions.
4.6/4.7
Concept Check
You have two separate beakers with aqueous
solutions, one with 4 “units” of potassium sulfate
and one with 3 “units” of barium nitrate.
b) Draw a molecular level diagram of the mixture
of the two solutions before a reaction has
taken place.
4.6/4.7
Concept Check
You have two separate beakers with aqueous
solutions, one with 4 “units” of potassium sulfate
and one with 3 “units” of barium nitrate.
c) Draw a molecular level diagram of the product
and solution formed after the reaction has
taken place.
4.6/4.7
Solution Stoichiometry Problems
• Identify the species present in the
combined solution.
• Write the balanced net ionic equation.
• Calculate the moles of reactants.
• Determine limiting reactant.
• Calculate the moles of product(s).
• Convert to grams or other units.
4.7
Determining
the Mass of
Product
Formed
Determining
the Mass of
Product
Formed
Acid-Base Reactions (Brønsted-Lowry)
• Acid – proton donor
• Base – proton acceptor
• For a strong acid and base reaction:
H+(aq) + OH–(aq)  H2O(l)
4.8
Neutralization of a Strong Acid by a
Strong Base
4.8
Performing
Calculations
for Acid-Base
Reactions
Neutralization
Reactions I
Neutralization
Reactions II
Neutralization
Titration
Key Titration Terms
• Titrant – solution of known concentration
used in titration
• Analyte – substance being analyzed
• Equivalence point – enough titrant added to
react exactly with the analyte
• Endpoint – the indicator changes color so
you can tell the equivalence point has been
reached
4.8
Performing Calculations for Acid-Base
Reactions
1.
2.
3.
4.
5.
List initial species and predict reaction.
Write balanced net ionic reaction.
Calculate moles of reactants.
Determine limiting reactant.
Calculate moles of required reactant or
product.
6. Convert to grams or volume, as required.
4.8
Oxidation-Reduction Reactions
(Redox Reactions)
• Reactions in which one or more electrons
are transferred.
4.9
Reaction of Sodium and Chlorine
4.9
Oxidation of
Copper Metal
by Nitric Acid
Rules for Assigning Oxidation States
1.
2.
3.
4.
5.
6.
7.
Oxidation state of an atom in an element = 0
Oxidation state of monatomic element = charge
Oxygen = 2 in covalent compounds (except in
peroxides where it = 1)
Hydrogen = +1 in covalent compounds
Fluorine = 1 in compounds
Sum of oxidation states = 0 in compounds
Sum of oxidation states = charge of the ion
4.9
Table 4.2 Rules for Assigning Oxidation
States
Exercise
Find the oxidation states for each of the elements
in each of the following compounds:
•
•
•
•
•
K2Cr2O7
CO32MnO2
PCl5
SF4
4.9
Redox Characteristics
•
•
•
•
Transfer of Electrons
Transfer may occur to form ions
Oxidation – increase in oxidation state
(loss of electrons); reducing agent
Reduction – decrease in oxidation state
(gain of electrons); oxidizing agent
4.9
Figure 4.20
A Summary
of OxidationReduction
Process
Concept Check
Which of the following are oxidation-reduction
reactions? Identify the oxidizing agent and the
reducing agent.
a) Zn(s) + 2HCl(aq)  ZnCl2(aq) + H2(g)
b) Cr2O72-(aq) + 2OH-(aq)  2CrO42-(aq) + H2O(l)
c) 2CuCl(aq)  CuCl2(aq) + Cu(s)
4.9
Balancing Oxidation-Reduction
Reactions
• Cr2O72-(aq) + SO32-(aq)  Cr3+(aq) + SO42-(aq)
• How can we balance this equation?
• First Steps:
– Separate into half-reactions
– Balance elements except H and O
4.10
The Half-Reaction Method
(Acidic Solution)
Method of Half Reactions
• Cr2O72-(aq)  2Cr3+(aq)
• SO32-(aq)  SO42-(aq)
• How many electrons are involved in each
half reaction?
4.10
Method of Half Reactions (continued)
• 6e- + Cr2O72-(aq)  2Cr3+(aq)
• SO32-(aq)  + SO42-(aq) + 2e• How can we balance the oxygen atoms?
4.10
Method of Half Reactions (continued)
• 6e- + Cr2O72-(aq)  Cr3+(aq) + 7H2O
• H2O +SO32-(aq)  + SO42-(aq) + 2e• How can we balance the hydrogen atoms?
4.10
Method of Half Reactions (continued)
•
•
•
•
This reaction occurs in an acidic solution.
14H+ + 6e- + Cr2O72-  2Cr3+ + 7H2O
H2O +SO32-  SO42- + 2e- + 2H+
How can we balance the electrons?
4.10
Method of Half Reactions (continued)
• 14H+ + 6e- + Cr2O72-  2Cr3+ + 7H2O
• 3[H2O +SO32-  SO42- + 2e- + 2H+]
• Final Balanced Equation:
Cr2O72- + 3SO32- + 8H+  2Cr3+ + 3SO42- + 4H2O
4.10
Exercise
Balance the following oxidation-reduction reaction
that occurs in acidic solution.
Br-(aq) + MnO4-(aq)  Br2(l)+ Mn2+(aq)
4.10
Half-Reaction Method –
Balancing in Base
1. Balance as in acid.
2. Add OH that equals H+ ions (both sides!)
3. Form water by combining H+, OH.
Cancel any water molecules that appear
on both sides.
4. Check elements and charges for balance.
4.10
For Review
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
Chemical reactions in solution are very important in everyday life.
Water is a polar solvent that dissolves many ionic and polar substances.
Electrolytes
˙Strong electrolyte: 100% dissociated to produce separate ions; strongly conducts an electric
current
˙Weak electrolyte: Only a small percentage of dissolved molecules produce ions; weakly
conducts an electric current
˙Nonelectrolyte: Dissolved substance produces no ions; does not conduct an electric current
Acids and bases
˙Arrhenius model: Acid: produces H+; Base: produces OH˙BrØnsted-Lowry model: Acid: proton donor; Base: proton acceptor
˙Strong acid: completely dissociates into separated H+ and anions
˙Weak acid: dissociates to a slight extent
Molarity
˙One way to describe solution composition
˙Moles of solute after dilution=moles of solute before dilution
Types of equations that describe solution reactions
˙Formula equation: all reactants and products are written as complete formulas
˙Complete ionic equation: all reactants and products that are strong electrolytes are written as
separated ions
˙Net ionic equation: only those compounds that undergo a change are written; spectator ions
are not included
Solubility rules
˙Based on experiment observation
˙Help predict the outcomes of precipitation reactions
For Review
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
˙Important types of solution reactions
Acid-base reactions: involve a transfer of H+ ions
˙Precipitation reactions: formation of a solid occurs
˙Oxidation-reduction reactions: involve electron transfer
Titrations
˙Measures the volume of a standard solution (titrant) needed to react with a
substance in solution
˙Stoichiometric(equivalence)point: the point at which the required amount of
titrant has been added to exactly react with the substance being analyzed
˙Endpoint: the point at which a chemical indicator changes color
Oxidation-reduction reactions
˙Oxidation states are assigned using a set of rules to keep track of electron
flow
˙Oxidation: increase in oxidation state (a loss of electrons)
˙Reduction: decrease in oxidation state (a gain of electrons)
˙Oxidizing agent: gains electrons (is reduced)
˙Reducing agent: loses electrons (is oxidized)
˙Equaitons for oxidation—reduction reactions are usually balanced by the
half-reaction method
Chapter Four
Types of Chemical Reactions and
Solution Stoichiometry
案例/討論
Figure 4.10a-c Steps Involved in the
Preparation of a Standard Aqueous Solution
Figure
4.11a-b
Measuring
Pipets and
Volumetric
Pipets
Measure
Liquid
Volume
Figure 4.12a-c A Measuring Pipet is Used to
Add Acetic Solution to a Volumetric Flask
Figure 4.14 a&b Reactant Solutions
Figure 4.15 a&b The Reaction of
K2CrO4 and Ba(NO3)2
Figure 4.19 The Reaction of Solid Sodium
and Gaseous Chlorine to Form Solid Sodium
Chloride
Figure 4.20
A Summary
of OxidationReduction
Process
The Half-Reaction Method
(Acidic Solution)
Figure 4.4a-c Electrical Conductivity of
Aqueous Solutions
The Half-Reaction Method
(Basic Solution)
An Aqueous
Solution of
Co(NO3)2.
Figure 4.10 Steps Involved in the
Preparation of a Standard Aqueous Solution
Figure 4.13 Yellow Aqueous Potassium
Figure 4.14a-b Reactant Solutions
Figure 4.15c
Solution PostReaction
Figure 4.16
Addition of
Silver Nitrate
to Aqueous
Solution of
Potassium
Chloride
Figure 4.17 Reaction of KCI(aq) with
AgNO3(aq) to form AgCI(s).
Lead
Sulfate
KOH and
Fe(NO3)3 Mix
to Create
Solid Fe(OH)3.
Figure
4.18a-c The
Titration of
an Acid with
a Base
Figure 4.19 The Reaction of Solid Sodium and
Gaseous Chlorine to Form Solid Sodium
Chloride
Oxidation of
Copper Metal
by Nitric Acid
Magnetite
Aluminum and Iodine Mix to Form
Aluminum Iodide
When Potassium Dichromate Reacts with
Ethanol, the Solution Contains Cr3+.
Table 4.1 Simple Rules for the
Solubility of Salts in Water
Table 4.2 Rules for Assigning Oxidation
States
Chapter Four
Types of Chemical Reactions
and Solution Stoichiometry
問答/練習
Question
•Which of the following solutions contains the
greatest total ion concentration?
–
–
–
–
One mole of potassium chloride dissolved in 1.0 L
of solution
One mole of iron(II) nitrate dissolved in 1.0 L of
solution
One mole of potassium hydroxide dissolved in 1.0
L of solution
One mole of sodium phosphate dissolved in 1.0 L
of solution
Answer
•d) One mole of sodium phosphate dissolved in 1.0 L of
solution
•Section 4.2, The Nature of Aqueous Solutions: Strong and
Weak Electrolytes
•All of the possible answers are strong electrolytes. The one
that dissociates into the most ions [KCl into 2 mol ions,
Fe(NO3)2 into 3 mol ions, KOH into 2 mol ions, Na3PO4 into
4 mol ions] is the answer.
Question
•Which of the following statements is true?
– If a substance is soluble, it must be an
electrolyte.
– If a substance is an electrolyte, it must be
soluble.
– Weak electrolytes must be less soluble than
strong electrolytes.
– Nonelectrolytes are nonsoluble.
Answer
•b)If a substance is an electrolyte, it must be
soluble.
•Section 4.2, The Nature of Aqueous Solutions:
Strong and Weak Electrolytes
•Electrolytes are substances that dissolve into ions.
Not all soluble substances are electrolytes (such as
table sugar).
Question
• Consider five solutions, each of which has the
same mass of solute in 100.0 mL of solution.
Which has the highest concentration as
measured in molarity?
–
–
–
–
–
KCl
NaCl
Na2SO4
NaF
CaCl2
Answer
• d) NaF
• Section 4.3, The Composition of Solutions
• The highest concentration as measured in
molarity for the same volume of solution will
be determined by the solute with the
smallest molar mass.
Question
• Which of the following solutions contains
the greatest number of ions?
– 400.0 mL of 0.10 M NaCl
– 300.0 mL of 0.10 M CaCl2
– 200.0 mL of 0.10 M FeCl3
– 800.0 mL of 0.10 M sucrose
Answer
•b)300.0 mL of 0.10 M CaCl2.
•Section 4.3, The Composition of Solutions
•The concentrations are all the same, so we must
look at the volumes and the number of ions per
compound. While each molecule of FeCl3 dissolves
into four ions, and each molecule of CaCl2
dissolves into only three ions, the greater volume of
the CaCl2 solution more than makes up for this
difference.
Question
• Lead(II) nitrate reacts with sodium chloride
in aqueous solution to form a precipitate.
What is the net ionic equation for this
reaction?
– Pb2+(aq) + 2NO3–(aq)  Pb(NO3)2(s)
– Na2+(aq) + Cl–(aq)  NaCl(s)
– Pb2+(aq) + 2Cl–(aq)  PbCl2(s)
– Na+(aq) + NO3–(aq)  NaNO3(s)
Answer
• c)
Pb2+(aq) + 2Cl–(aq)  PbCl2(s)
• Section 4.5, Precipitation Reactions; Section 4.6,
Describing Reactions in Solution
• Both of the reactants are strong electrolytes and
completely break up into ions, but the product,
lead(II) chloride, is a precipitate.
Question
•Aqueous solutions of sodium sulfide and
copper(II) chloride are mixed together. Which
statement is correct?
– Both NaCl and CuS will precipitate from
solution.
– No precipitate will form.
– Only CuS will precipitate from solution.
– Only NaCl will precipitate from solution.
Answer
• c) Only CuS will precipitate from solution.
• Section 4.5, Precipitation Reactions
• Based on the simple rules for solubility of salts in
water, sodium chloride will not form a precipitate
while copper(II) sulfide will.
Question
• An aqueous solution of barium nitrate reacts with
an aqueous solution of sodium sulfate. Identify
the solid and indicate its coefficient in the
balanced equation.
–
–
–
–
–
NaNO3; 1
BaSO4; 1
NaNO3; 2
BaSO4; 2
None of the above
Answer
• b) BaSO4; 1
• Section 4.5, Precipitation Reactions
• Based on the simple rules for solubility of salts
in water, barium sulfate will precipitate as a
solid. The balanced equation is
• Ba(NO3)2(aq) + Na2SO4(aq) → BaSO4(s) +
2NaNO3(aq)
Question
• You have separate aqueous solutions of NaOH
and Ca(OH)2 with the same concentrations. You
wish to neutralize an aqueous solution of HCl.
Which basic solution would require more volume
to neutralize the acid?
– The NaOH solution.
– The Ca(OH)2 solution.
– More information is needed to answer this question.
Answer
• a) The NaOH solution.
• Section 4.8, Acid–Base Reactions
• The basic solution requiring the greater
volume to neutralize the acid is the one
with the smaller number of hydroxide ions
available to react with the hydrogen ions.
Question
• For the reaction of sodium bromide with
chlorine gas to form sodium chloride and
bromine, what are the appropriate halfreactions? (ox = oxidation; re = reduction)
–
–
–
–
ox:
ox:
ox:
ox:
Cl2 + 2e–  2Cl–; re: 2Br–  Br2 + 2e–
2Br–  Br2 + 2e–; re: Cl2 + 2e–  2Cl–
Cl + e–  Cl–; re: Br  Br+ + e–
2Cl–  Cl2 + 2e–  ; re: Na+ + e–  Na
Answer
•b) ox: 2Br–  Br2 + 2e–; re: Cl2 + 2e–  2Cl–
•Section 4.9, Oxidation–Reduction Reactions; Section 4.10,
Balancing Oxidation–Reduction Equations
•The conversion of bromide ion to bromine represents an
oxidation, with the loss of two electrons. The conversion of
chlorine to chloride ion represents a reduction, requiring two
electrons.
Question
• How many of the following are oxidation–
reduction reactions?
•
i.
PCl3 + Cl2  PCl5
•
ii.
Cu + 2AgNO3  Cu(NO3)2 + 2Ag
•
iii.
CO2 + 2LiOH  Li2CO3 + H2O
•
iv.
FeCl2 + 2NaOH  Fe(OH)2 + 2NaCl
a) 0
b) 1
c) 2
d) 4
Answer
• c) 2
• Section 4.9, Oxidation–Reduction Reactions
• The answers include (i), where phosphorus
undergoes an oxidation from +3 to +5 and
chlorine undergoes a reduction from 0 to –1, and
(ii), where copper undergoes an oxidation from 0
to +2 and silver undergoes a reduction from +1 to
0.
Question
• Which of the following is not an oxidation–
reduction reaction?
– A precipitation reaction.
– A reaction in which a metal reacts with a
nonmetal.
– A combustion reaction.
– The reaction of a metal with an acid.
– All of the above are oxidation–reduction
reactions.
Answer
• a) A precipitation reaction.
• Section 4.9, Oxidation–Reduction
Reactions
• In a precipitation reaction, soluble ions
combine to form an insoluble solid with the
ions in their same oxidation states. The
other possible answers involve elements (in
the zero oxidation state) reacting to ions
with nonzero charges.
Question
• What are the oxidation numbers of carbon
in CO2 and CO32–, respectively?
– +2, +6
– +4, +6
– –4, –4
– –4, –6
– +4, +4
Answer
• e) +4, +4
• Section 4.9, Oxidation–Reduction Reactions
• If the oxidation state of oxygen in the oxide is –2,
the carbon must be +4 for the resulting CO2 to be
neutral, and the carbon must be +4 for the CO32–
to have a –2 charge on the ion.
Question
• Identify the type of unbalanced reaction
• Mg + HCl  MgCl2 + H2 using the following
choices:
– Precipitation reaction
– Acid–base reaction
– Oxidation–reduction reaction
– Combustion reaction
Answer
• c) Oxidation–reduction reaction
• Section 4.9, Oxidation–Reduction Reactions
• This particular reaction involves an element
changing into an ion and an ion changing into the
element, both of which result in changes in the
oxidation states of the species.
Question
•Each of the following results in a chemical reaction.
Which of these is not an oxidation–reduction
reaction?
–
–
–
–
–
Methane gas is burned in air.
Iodine crystals are added to an aqueous solution of
silver nitrate.
A piece of silver metal is placed in an aqueous
solution of copper(II) nitrate.
Chlorine gas is bubbled through an aqueous
solution of sodium bromide.
Aqueous solutions of lead(II) nitrate and sodium
iodide are mixed together.
Answer
•e) Aqueous solutions of lead(II) nitrate and
sodium iodide are mixed together.
•Section 4.9, Oxidation–Reduction Reactions
•Choice (e) describes a precipitation reaction. The
other choices all include elements that become part
of a compound.
Question
• Which of the following compounds contains
nitrogen with the highest oxidation number?
– NH3
– NO2
– NCl3
– N2
– NO
Answer
•b) NO2
•Section 4.9, Oxidation–Reduction Reactions
•The oxidation states of nitrogen are as
follows: NH3, –3; NO2, +4; NCl3, +3; N2, 0;
NO, +2.
Chemical Impact
Chemical Impact
Arrhenius A Man with Solutions (p.132)
Science is a human endeavor, subject to frailties
and governed by personalities, politics, and prejudices.
One of the best illustrations of the often bumpy path of
The advancement of scientific knowledge is the story of
Swedish chemist Svante Arrhenius.
……
Such a setbakc could have ended his scientific career, but
Arrhenius was a crusader; he was determined to see his
theory thriumph. He promptly embarked on a political
campaign, enlisted the aid of several prominent scientists,
to get his theory accepted.
Ultimately, the ionic theory triumphed. Arrhenius’ fame
Spread, and honors heaped on him, culminating in the
Nobel Prize in chemistry in 1903. Not one to rest on his
laurels., Arrhenius turned to new fields, including astronomy,
He formulated a new theory that the solar system may have
Come into being through the collision of stars. His exceptional
Versatility led him to study the use of serums to fight disease,
Energy resources and conservation, and the origin of life.
Chemical Impact: Tiny Laboratories (p.138)
Labchip by Caliper Technologies (Palo Alto, CA), showing photolithographically
etched fluid channels (in red). Channels are typically 70 µm wide and 10 µm deep.
Photo Courtesy Caliper Technologies.
Chemical Impact
Iron Zeros In On Pollution (p.156)
Fe(s) + RCl(aq) + H+ (aq)  Fe2+ (aq)  RH(aq)  Cl- ( aq)
(Chlorinated organic compound)
Chemical Impact : Pearly White (p.159)
Ca5(PO4)3(OH)
(Ca10(PO4)6(OH)2 because there
are two molecules in a unit cell.)
瑭瓷
牙本質
牙髓
牙齦
牙骨質
Carbamide Peroxide Teeth Whiteners:
1:1 mixture of urea and hydrogen peroxide （H2O2）,
glycerin (see next page), statnnate （SnO44-）,
pyrophosphate salts (P2O7 4-, preservatives) and
flavoring agents.
Glycerol (C3H5(OH)3) 甘油（甘醇，丙三醇）
IUPAC name
Propane-1,2,3-triol
Other names
glycerin
glycerine
propane-1,2,3-triol
1,2,3-propanetriol
1,2,3-trihydroxypropane
glyceritol
glycyl alcohol
Chemical Impact :
Aging: Does It Involve Oxidation (p.160)
Wrinkles, susceptibility, subsequently, activated molecules,
immune system, cell membrane, detrimental, irreplaceable,
fall into this category.
Vitamin E (anti-oxidant), red blood cell (RBC),
superoxide dismutase (SOD, anti-oxidant), gerontology,
rheumatoid arthritis, muscular dystrophy.
Superoxide dismutase (超氧化歧化酶)
The enzyme superoxide dismutase (SOD, EC 1.15.1.1), catalyzes the
dismutation of superoxide into oxygen and hydrogen peroxide. As
such, it is an important antioxidant defense in nearly all cells exposed
to oxygen. One of the exceedingly rare exceptions is
Lactobacillus plantarum and related lactobacilli, which use a
different mechanism.
The SOD-catalysed dismutation of superoxide may be written with the following half-reactions :
M (n+1)+ − SOD + O 2− → M n+ − SOD + O 2
M n+ − SOD + O 2− + 2H + → M (n+1)+ − SOD + H2O2.
where M = Cu (n=1) ; Mn (n=2) ; Fe (n=2) ; Ni (n=2).
In this reaction the oxidation state of the metal cation oscillates between n and n+1
第4章習題涉及的分子或反應