6 Some Types of Chemical Reactions. Outline 1. Aqueous Solutions 水溶液 : An Introduction 2....

66Some Types of Chemical

Reactions

OutlineOutline1. Aqueous Solutions 水溶液 : An Introduction2. Reactions in Aqueous Solutions Naming Some Inorganic Compounds3. Naming Binary Compounds 二元化合物的命名4. Naming Ternary Acids and Their Salts 三元酸的命名 Classifying Chemical Reactions5. Oxidation-Reduction Reactions: An Introduction6. Combination Reactions 化合反應7. Decomposition Reactions 分解反應8. Displacement Reactions 分解反應9. Metathesis Reactions 複分解反應10. Gas-Formation Reactions11. Summary of Reaction Types

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Aqueous Solutions: An IntroductionAqueous Solutions: An IntroductionElectrolytes and Extent of Ionization 電解質及電解游離

程度• Electrolytes are substances whose aqueous solutions

conduct electric current 凡化合物溶於水能導電的物質即稱電解質

– Nonelectrolytes – solutes that do not conduct electricity in water 非電解質

– Weak electrolytes: conduct electricity poorly in dilute aqueous current 弱電解質 : 導電性較差

– Strong electrolytes: conduct electricity well in dilute aqueous current 強電解質 : 導電性較好

• The strength of a electrolyte depends on the number of ions in solution, and also on the charges on these ions 導電性的強度取決於溶液的離子數目及離子的電荷

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Nonelectrolytes Weak electrolytes strong electrolytes

Aqueous Solutions: An Aqueous Solutions: An IntroductionIntroduction

• C2H5OH - ethanol• C6H12O6 – glucose 葡萄糖 (blood sugar)

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Nonelectrolytes – solutes that do not conduct electricity in water

C

HOHO

H

H

H

C

HHC H

C

CH

O

CCOH

OH

H

• C12H22O11 – sucrose 蔗糖 (table sugar)

C

OC

C

C C

CH2

H

H

OH

H

OH

OH

HO

H

OH

C C

C

O

C

CH2

H

OH

H

H

OH

CH2

OH

OH


•The reason nonelectrolytes do not conduct electricity is because they do not form ions in solution.

• ions conduct electricity in solution

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Acid: a substance that produces hydrogen ions, H+, in aqueous solutions

Base: a substance that produces hydroxide ions, OH-, in aqueous solutions

Salt: a compound that contains a cation other than H+, and an anion other than hydroxide ion, OH- , or oxide ion, O2-

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•Classification of solutes–strong electrolytes 強電解質 - conduct electricity extremely

well in dilute aqueous solutions•Examples of strong electrolytes1. HCl, HNO3, etc.

•strong soluble acids2. NaOH, KOH, etc.

•strong soluble bases3. NaCl, KBr, etc.

•soluble ionic salts•ionize in water essentially 100%

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檸檬酸


•Classification of solutes– weak electrolytes - conduct electricity

poorly in dilute aqueous solutions1.CH3COOH, (COOH)2

•weak acids2.NH3, Fe(OH)3

•weak bases3.some soluble covalent salts

•ionize in water much less than 100%

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Strong and Weak Acids 強酸及弱酸•Acids are substances that generate H+ in aqueous

solutions.•Strong acids ionize 100% in water.

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HCl(g) H+(aq) + Cl-

(aq)100%

HNO3 + H2O H3O+(aq) + NO-

3(aq)

HNO3 H+(aq) + NO-

3(aq)H2O

100%


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氫氯酸氫溴酸

氫碘酸硝酸

氯酸

硫酸

過氯酸

strong acids--ionize almost 100% Table 6-1


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Weak acids--Typically ionize 10% or less!

氫氟酸醋酸

亞硝酸氰化氫

碳酸

亞硫酸

磷酸

草酸

Table 6-2


Organic acid 有機酸• Contain the carboxylate group, ―COOH• Most organic acids are weak• ― COO- and H+

• Naturally occurring organic weak acid– Tartaric acid (grapes) 酒石酸– Lactic acid (sour milk) 乳酸– Formic acid (ants) 甲酸或稱蟻酸

Inorganic Acid 無機酸• Often called mineral acids 礦物酸• Contain Carbon but considered to be inorganic acid

– Carbonic acid, H2CO3 碳酸– Hydrocyanic acid, HCN 氰化氫

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Example 6-1 Strong and Weak AcidIn the following lists of common acids, which are strong and which are weak?(a) H3PO4, HCl, H2CO3, HNO3

(b) HClO4, H2SO4, HClO, HF.

(a) HCl, HNO3 are strong acids H3PO4, H2CO3 are weak acids(b) HClO4, H2SO4, are strong acids HClO, HF are weak acids

Example 6-1 Strong and Weak AcidIn the following lists of common acids, which are strong and which are weak?(a) H3PO4, HCl, H2CO3, HNO3

(b) HClO4, H2SO4, HClO, HF.

(a) HCl, HNO3 are strong acids H3PO4, H2CO3 are weak acids(b) HClO4, H2SO4, are strong acids HClO, HF are weak acids

Exercise 5, 7


Reversible Reactions 可逆反應• Strong acid : the ionization of HCl in water is nearly

complete–one direction

• All weak inorganic acids ionize reversibly or in equilibrium reactions.

–This is why they ionize less than 100%.• Correct chemical symbolism for equilibrium reactions

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CH3COOH (aq) CH3COO-(aq) + H+

(aq)

Reversible Reactions 可逆反應


Strong Bases, Insoluble Bases, and Weak Bases 強鹼 , 不可溶鹼及弱鹼

•Strong Bases 強鹼–Characteristic of common inorganic bases is that they

produce OH- ions in solution.–Similarly to strong acids, strong bases ionize 100% in water.

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NaOH Na+(aq) + OH-

(aq)H2O

Ba(OH)2 Ba+2(aq) + 2OH-

(aq)H2O

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氫氧化鋰氫氧化鈉

氫氧化鉀氫氧化銣

氫氧化銫

氫氧化鈣

氫氧化鍶

氫氧化鋇


Notice that they are all hydroxides of IA and IIA metals

Table 6-2


Strong Bases, Insoluble Bases, and Weak Bases• Insoluble bases

– Ionic compounds that are insoluble in water, consequently, not very basic

–Cu(OH)2, Zn(OH)2, Fe(OH)2氫氧化亞鐵 , Fe(OH)3 •Weak bases

–are covalent compounds that ionize slightly in water.–Ammonia is most common weak base-- NH3–Closely related N-containing compounds, the amines

• Methylamine CH3NH2甲胺 • Caffeine 咖啡因

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NH3(aq) + H2O(l) NH4+

(aq) + OH-(aq)

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Example 6-2 Classifying BasesFrom the following lists, choose (i) the strong bases, (ii) the insoluble bases, and (iii) the weak bases.(a) NaOH, Cu(OH)2, Pb(OH)2, Ba(OH)2

(b) Fe(OH)3, KOH, Mg(OH)2, Sr(OH)2, NH3

(a) (i)The strong bases: NaOH, Ba(OH)2

(ii)The insoluble bases: Cu(OH)2, Pb(OH)2

(b) (i)The strong bases: KOH, Sr(OH)2

(ii)The insoluble bases: Fe(OH)3, Mg(OH)2

(iii)The weak bases: NH3

Example 6-2 Classifying BasesFrom the following lists, choose (i) the strong bases, (ii) the insoluble bases, and (iii) the weak bases.(a) NaOH, Cu(OH)2, Pb(OH)2, Ba(OH)2

(b) Fe(OH)3, KOH, Mg(OH)2, Sr(OH)2, NH3

(a) (i)The strong bases: NaOH, Ba(OH)2

(ii)The insoluble bases: Cu(OH)2, Pb(OH)2

(b) (i)The strong bases: KOH, Sr(OH)2

(ii)The insoluble bases: Fe(OH)3, Mg(OH)2

(iii)The weak bases: NH3

Exercise 8, 10


Solubility 溶解度 Guidelines for Compounds in Aqueous Solutions

– It is very important that you know these guidelines and It is very important that you know these guidelines and how to apply them in reactions.how to apply them in reactions.

1) Common inorganic acids and low-molecular-weight organic acids are water soluble

2) All common compounds of the Group IA metal ions and the ammonium ion are water soluble.

– LiLi++, Na Na++, K K++, Rb Rb++, Cs Cs++, and NHNH44++

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3) Common nitrates, acetates, chlorates, and perchlorates are water soluble

– NONO33--, CH CH33COOCOO--, ClO ClO33

--, and ClOClO44--

4) Common chlorides 氯化物 are water soluble– Exceptions – AgClAgCl, Hg Hg22ClCl22, & PbClPbCl22 (( 例外例外 ))– Common bromides and iodides behave similarly to

chlorides.– Common fluorides are water soluble.

•Exceptions – MgFMgF22, CaF CaF22, SrF SrF22, BaF BaF22, and PbF PbF22

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硝酸根醋酸根氯酸根過氯酸根


5)Common sulfates are water soluble–Exceptions – PbSO PbSO44, BaSO BaSO44, & HgSO HgSO44

–Moderately soluble – CaSO CaSO44, SrSO SrSO44, & Ag Ag22SOSO44

6)Common metal hydroxides are water insolubleinsoluble–Exceptions – LiOH, NaOH, KOH, RbOH LiOH, NaOH, KOH, RbOH & CsOH (IA CsOH (IA

metal hydroxides)metal hydroxides)

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7) Common carbonates, phosphates, and arsenates are water insolubleinsoluble

碳酸鹽 , 磷酸鹽及砷酸鹽 – COCO33

2-2-, PO PO443-3-, & AsO AsO44

3-3-

– Exceptions- IA metals IA metals and NH NH44++

Ba(COBa(CO33))22 is moderately soluble is moderately soluble– Moderately soluble – MgCO MgCO33

8) Common sulfides (S2-) are water insolubleinsoluble– Exceptions – IA metals IA metals and NH NH44

++ plus IIA metals IIA metals

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Insoluble

soluble

Aqueous Solutions: An Aqueous Solutions: An IntroductionIntroductionTable 6-4

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Example 6-3 Solubility of Some Common Ionic SaltFrom the following compounds, choose (a) those that are likely to be soluble in water and (b) those that are likely to be insoluble: NaBr, Cu(OH)2, PbCl2, AgI, Fe2O3, Mg(NO3)2, (NH4)2SO4

(a)The soluble compound: NaBr, Mg(NO3)2, (NH4)2SO4

(b)The insoluble compound: Cu(OH)2, PbCl2, AgI, Fe2O3

Example 6-3 Solubility of Some Common Ionic SaltFrom the following compounds, choose (a) those that are likely to be soluble in water and (b) those that are likely to be insoluble: NaBr, Cu(OH)2, PbCl2, AgI, Fe2O3, Mg(NO3)2, (NH4)2SO4

(a)The soluble compound: NaBr, Mg(NO3)2, (NH4)2SO4

(b)The insoluble compound: Cu(OH)2, PbCl2, AgI, Fe2O3 Exercise 14, 16

Reactions in Reactions in Aqueous SolutionsAqueous Solutions

There are three ways to write reactions in aqueous solutions.

1. Molecular equation 分子方程式 – Show all reactants & products in molecular or ionic form

(more active metal replaces the compound)

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Zn(s) + CuSO4(aq) ZnSO4(aq) +Cu(s)

Cu(s) + 2AgNO3(aq) Cu(NO3)2 (aq) + 2Ag(s)

Soluble ionic compounds



2. Total ionic equation 完全離子方程式– Show the ions and molecules as they exist in solution

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Zn(s) + Cu2+ (aq)+SO4

2-(aq) Zn2+

(aq) +SO4

2-(aq) +Cu(s)

2[Ag+ (s) +NO3

- (aq)]+ Cu2+

(aq) 1Ag(s) +[Cu2+(aq)+2NO3

-(aq) ]

NO3- ions do not participate in the reaction

They do not change Spectator ions 旁觀離子



3. Net ionic equation 淨離子方程式 – Shows ions that participate in reaction and removes

spectator ions 旁觀離子

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Zn(s) + Cu2+ (aq)+SO4

2-(aq) Zn2+

(aq) +SO4

2-(aq) +Cu(s)

2[Ag+ (s) +NO3

- (aq)]+ Cu2+

(aq) 2Ag(s) +[Cu2+(aq)+2NO3

-(aq) ]

Zn(s) + Cu2+(aq) Zn2+

(aq) +Cu(s)

2Ag+ (s) + Cu2+

(aq) 2Ag(s) +Cu2+(aq)


• In the total and net ionic equations the only common substances that should be written as ions are:

a. Strong acidsb. Strong basesc. Soluble ionic salts

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Table 6-5

Naming Some Inorganic CompoundsNaming Some Inorganic Compounds無機化合物的命名無機化合物的命名

IUPACIUPAC 國際純粹與應用化學聯合會國際純粹與應用化學聯合會• Binary compounds ( 二元化合物 ) are made of two

elements.–metal + nonmetal = ionic compound ( 離子化合物 )–nonmetal + nonmetal = covalent compound ( 共價化合物 )

• Name the more metallic element first.–Use the element’s name.

• Name the less metallic element second. –Add the suffix “ide” to the element’s stem. ( 字尾加上 ide )

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陽離子陰離子

Table 6-6

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Naming Some Naming Some Inorganic CompoundsInorganic Compounds

•Nonmetal StemsNonmetal StemsElement StemBoron (B) borCarbon (C) carbSilicon (Si) silicNitrogen (N) nitrPhosphorus (P) phosphArsenic (As) arsenAntimony (Sb) antimon

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Element StemOxygen (O) oxSulfur (S) sulfSelenium (Se) selenTellurium (Te) tellurHydrogen (H) hydrFluorine (F) fluorChlorine (Cl) chlorBromine (Br) bromIodine (I) iod


•Binary Ionic Compounds Binary Ionic Compounds are made of a metal cation and a nonmetal anion.

– Cation named first– Anion named second

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LiBr MgCl2 Li2S Al2O3 Na3P Mg3N2

lithium bromide magnesium chloride lithium sulfide aluminum oxide sodium phosphide magnesium nitrideNotice that binary ionic compounds with metals having one

oxidation state (representative metals) do not use prefixes or Roman numerals.


• Binary ionic compounds containing Binary ionic compounds containing metalsmetals that that exhibit more than one oxidation stateexhibit more than one oxidation state

• Metals exhibiting multiple oxidation states are:1. most of the transition metals2. metals in groups 3A (except Al), 4A, & 5A

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• There are two methods to name these compounds.1. Older method

– add suffix “ic” to element’s Latin name for higher oxidation state

– add suffix “ous” to element’s Latin name for lower oxidation state

2. Modern method– use Roman numerals in parentheses to indicate

metal’s oxidation state

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CompoundFeBr2 +2FeBr3 +3SnO +2SnO2 +4TiCl2 +2TiCl3 +3TiCl4 +4

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Modern SystemIron (II) bromideIron (III) bromideTin (II) oxideTin (IV) oxideTitanium (II) chlorideTitanium (III) chlorideTitanium (IV) chloride

Old System

ferrous bromideferric bromidestannous oxidestannic oxidetitanous chlorideTitanic chloridedoes not workdoes not work


Pseudobinary ionic compoundsPseudobinary ionic compounds• There are three polyatomic ions that commonly form

binary ionic compounds.1.OH- hydroxide2.CN- cyanide3.NH4

+ ammonium

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Pseudo = false 假的


KOHBa(OH)2

Al(OH)3

Fe(OH)2

Fe(OH)3

Ba(CN)2

(NH4)2SNH4CNCu(OH)2

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Use binary ionic compound naming system.potassium hydroxidebarium hydroxidealuminum hydroxideiron (II) hydroxideiron (III) hydroxidebarium cyanideammonium sulfideammonium cyanidecopper (II) hydroxide


• Binary acids Binary acids are binary compounds consisting of hydrogen and a nonmetal.

• Compounds are usually gases at room temperature and pressure.– Nomenclature for the gaseous compounds is hydrogen

(stem)ide.• When the compounds are dissolved in water they form

acidic solutions.– Nomenclature for the acidic solutions is hydro (stem)ic

acid.

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FormulaHClHFH2SHCN

Name of compoundhydrogen chloridehydrogen fluoridehydrogen sulfidehydrogen cyanide

Name of Aqueous solutionhydrochloric acid, HCl(aq)

hydrofluoric acid, HF(aq)

hydrosulfuric acid, H2S(aq)

Hydrocyanic acid, HCN(aq)


• Binary covalent molecular compounds composed of Binary covalent molecular compounds composed of two two nonmetals nonmetals other than hydrogenother than hydrogen – Nomenclature must include prefixes that specify the

number of atoms of each element in the compound.• Use the minimum number of prefixes necessary to

specify the compound. – Frequently drop the prefix mono- 12 di 5 penta 8 oct3 tri 6 hexa 9 nona4 tetra 7 hepta 10 deca

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FormulaCOCO2

SO3

OF2

P4O6

P4O10

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Namecarbon monoxidecarbon dioxidesulfur trioxideoxygen difluoridetetraphosphorus hexoxidetetraphosphorus decoxide


•The oxides of nitrogen illustrate why covalent compounds need prefixes and ionic compounds do not.

•Formula Old Name Modern Name•N2O nitrous oxide dinitrogen monoxide•NO nitric oxide nitrogen monoxide•N2O3 nitrogen trioxide dinitrogen trioxide•NO2 nitrogen dioxide nitrogen dioxide•N2O4 nitrogen tetroxide dinitrogen tetroxide•N2O5 nitrogen pentoxide dinitrogen pentoxide

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• Ternary Acids Ternary Acids and Their Salts and Their Salts are made of three elements.– The elements are H, O, & a nonmetal.

• Two of the compounds are chosen as the basis for the nomenclature system.– Higher oxidation state for nonmetal is named (stem)ic

acid.– Lower oxidation state for nonmetal is named (stem)ous

acid• Salts are named based on the acids.

– Anions of -ic acids make “ate” salts.– Anions of -ous acids make “ite” salts.

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Naming Some Naming Some Inorganic Compounds Inorganic Compounds Table 6-7


• Salts are formed by the reaction of the acid with a strong base.

Acid SaltHNO2 NaNO2

nitrous acid sodium nitriteHNO3 NaNO3

nitric acid sodium nitrateH2SO3 Na2SO3

sulfurous acid sodium sulfiteH2SO4 Na2SO4

sulfuric acid sodium sulfateHClO2 NaClO2

chlorous acid sodium chloriteHClO3 NaClO3

chloric acid sodium chlorate

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• There are two other possible acid and salt combinations.

• Acids that have a higher oxidation state than the “ic” acid are given the prefix “per”.– These acids and salts will have one more O atom than the

“ic” acid.• Acids that have a lower oxidation state than the

“ous” acid are given the prefix “hypo”. – These acids and salts will have one less O atom than the

“ous” acid.

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• Illustrate this series of acids and salts with the Cl ternary acids and salts.

Acid Na SaltHClO NaClO

hypochlorous acid sodium hypochloriteHClO2 NaClO2

chlorous acid sodium chloriteHClO3 NaClO3

chloric acid sodium chlorateHClO4 NaClO4

perchloric acid sodium perchlorate

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• Acidic SaltsAcidic Salts are made from ternary acids that retain one or more of their acidic hydrogen atoms.– Made from acid base reactions where there is an

insufficient amount of base to react with all of the hydrogen atoms.

• Old system used the prefix “bi”“bi” to denote the hydrogen atom.

• Modern system uses prefixes and the word hydrogen.

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• NaHCO3 Old system sodium bicarbonate Modern system sodium hydrogen carbonate

• KHSO4 Old system potassium bisulfate Modern system potassium hydrogen sulfate

• KH2PO4Old system potassium bis biphosphate Modern system potassium dihydrogen phosphate

• K2HPO4 Old system potassium biphosphateModern system potassium hydrogen phosphate

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Naming SomeNaming SomeInorganic CompoundsInorganic Compounds

• Basic SaltsBasic Salts are analogous to acidic salts. – The salts have one or more basic hydroxides remaining in

the compound.• Basic salts are formed by acid-base reactions with

insufficient amounts of the acid to react with all of the hydroxide ions.

• Use prefixes to indicate the number of hydroxide groups.

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Naming SomeNaming SomeInorganic CompoundsInorganic Compounds

• Ca(OH)Cl – calcium monohydroxy chloride

• Al(OH)Cl2 – aluminum monohydroxy chloride

• Al(OH)2Cl – aluminum dihydroxy chloride

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Oxidation-Reduction Reactions: Oxidation-Reduction Reactions: An IntroductionAn Introduction

•Oxidation is an increase in the oxidation number. ( 氧化數增加 )

– Corresponds to the loss of electrons. 失去電子•Reduction is a decrease in the oxidation number. ( 氧化數減少 )

– Good mnemonic – reduction reduces the oxidation number.

– Corresponds to the gain of electrons 得到電子

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•Oxidizing agents 氧化劑 are chemical species that:1.oxidize some other substance2.contain atoms that are reduced in the reaction 3.gain electrons

•Reducing agents 還原劑 are chemical species that:1.reduce some other substance 2.contain atoms that are oxidized in the reaction3.lose electrons

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• Two examples of oxidation-reduction or redox reactions.

• KMnO4 and Fe2+

– Fe2+ is oxidized to Fe3+

– MnO41- is reduced to Mn2+

• Combustion reactions are redox reactions• Combustion of Mg

– Mg is oxidized to MgO– O2 is reduced to O2-

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57

2Fe(s) + 3Cl2(g) 2FeCl3(s)

0 0 +3 -1

Reducing agent Oxidizing agent

2FeBr3(aq) + 3Cl2(g) 2FeCl3(s) + 3Br2(l)

0 +3 -1+3 -1 0


Cl2 + H2O HCl + HClO

0 +1-1

Reducing agentOxidizing agent

Disproportionation Reaction 不均化反應 is a redox reaction in which the same element is oxidized and reduced.Disproportionation Reaction 不均化反應 is a redox reaction in which the same element is oxidized and reduced.


• Example 4-2: Write and balance the formula unit, total ionic, and net ionic equations for the oxidation of sulfurous acid to sulfuric acid by oxygen in acidic aqueous solution.

• Formula unit equation

• Total ionic equation

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2H2SO3 (aq) + O2(g) 2H2SO4 (aq)

2H2SO3 (aq) + O2(g) 4H+ (aq)+ 2SO42-

(aq)

2H2SO3 (aq) + O2(g) 4H+ (aq)+ 2SO42-

(aq)

0 +6+4 -2


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Example 6-4 Redox ReactionsWrite each of the following formula unit equations as a net ionic equation if the two differ. Which ones are redox reactions? For the redox reactions, identify the oxidizing agent, the reducing agent, the species oxidized, and the species reduced?

Example 6-4 Redox ReactionsWrite each of the following formula unit equations as a net ionic equation if the two differ. Which ones are redox reactions? For the redox reactions, identify the oxidizing agent, the reducing agent, the species oxidized, and the species reduced?

(a) 2AgNO3 (aq) + Cu(s) Cu(NO3)2(aq)+ 2Ag (s)

(b) 4KClO3 (s) KCl(s)+ 3KClO4(s)

(c) 3AgNO3 (aq) + K3PO4(aq) Ag3 PO4(s)+ 3KNO3(aq)

(a) 2[Ag+(aq)+NO3

-(aq)] + Cu(s) [Cu+2

(aq) +2NO3

- (aq)]+ 2Ag (s)

0+1 +5 -2 +5 -20 +2

Reducing agentOxidizing agent

(b) 4KClO3 (s) KCl(s)+ 3KClO4(s)

+1 +1 +1+5 +7-2 -2-1 Disproportionation Reaction

(c) 3Ag+ (aq)+PO4

3-(aq) Ag3 PO4(s)

+1 +1+5 +5-2 -2Not a Redox Reaction

Exercise 56, 59

Combination ReactionsCombination Reactions化合反應化合反應

• Combination reactions occur when two or more substances combine to form a compound.

• There are three basic types of combination reactions.

1. Two elements react to form a new compound2. An element and a compound react to form one

new compound3. Two compounds react to form one compound

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Combination ReactionsCombination Reactions1.Element + Element Compound (oxidation-reduction reaction)

A. Metal + Nonmetal Binary Ionic Compound

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2Na (s) + Cl2(g) 2NaCl (s)

2M (s) + X2(g) 2(M+X-) (s) M: Li, Na, K, Rb, CsX: F, Cl, Br, I

M (s) + X2(g) MX2(s) M: Be, Mg, Ca, Sr, BaX: F, Cl, Br, I

Mg (s) + F2(g) MgF2(s)

Sodium Chloride

Magnesium Fluoride

Combination ReactionsCombination Reactions1. Element + Element Compound

B. Nonmetal + Nonmetal Covalent Binary Compound

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P4 (s) + 5O2(g) P4O10(s)

P4 (s) + 6Cl2(g) 4PCl3(l)

Combination ReactionsCombination Reactions1.Element + Element CompoundB. Nonmetal + Nonmetal Covalent Binary Compound

• Can control which product is made with the reaction conditions.

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2As (s) + 3Cl2(g) 2AsCl3(s) In limited chlorine

2As (s) + 5Cl2(g) 2AsCl5(s) In excess chlorine

Se (s) + 2F2(g) SeF4(s) In limited fluorineSe (s) + 3F2(g) SeF6(s) In excess fluorine

A higher oxidation state of a nonmetal is formed when it reacts with an excess of another nonmetal

Combination ReactionsCombination Reactions2. Compound + Element Compound (oxidation-reduction reaction)

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AsCl3 (s) + 2Cl2(g) AsCl5(s)

PCl3 (l) + Cl2(g) PCl5(s)

SF4 (g) + F2(g) SF6(g)

The reaction of oxygen with oxides of nonmetals is an example of this type of combination reaction.

2CO (g) + O2(g) 2CO2(g)

2SO2 (g) + O2(g) 2SO3(g)catalyst

P4O6 (g) + 2O2(g) P4O10(g)

Combination ReactionsCombination Reactions3. Compound + Compound Compound

–Calcium oxide with carbon dioxide to produce calcium carbonate

–Pyrosulfuric acid is produced by dissolving sulfur trioxide in concentrated sulfuric acid

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CaO (s) + CO2(g) CaCO3(s)

SO3 (g) + H2SO4(l) H2S2O7(l)–Pyrosulfuric acid is then diluted with water to make H2SO4

H2S2O7 (l) + H2O(l) 2H2SO4(l)

–Oxides of the Group 1A and 2A metals react with water to form metal hydroxides

CaO (s) + H2O(l) Ca(OH)2(aq)

Decomposition ReactionsDecomposition Reactions分解反應分解反應

•Decomposition reactions occur when one compound decomposes to form:

1. Two elements2. One or more elements and one or more compounds3. Two or more compounds

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Decomposition ReactionsDecomposition Reactions1. Compound Element + Element

• decomposition of dinitrogen oxide

• decomposition of calcium chloride

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• decomposition of silver halides

2N2O(g) 2N2(g) + O2(g)

CaCl2(l) Ca(l) + Cl2(g)electricity

2AgBr(s) 2Ag(s) + Br2(g)h

Decomposition ReactionsDecomposition Reactions2. Compound One Element + Compound(s)

– The alkali metal chlorites, such as KClO3, decompose when heated to produce the corresponding chlorides and liberate oxygen

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2KClO3 (s) 2KCl(s) + 3O2(g)MnO2

Potassium chlorate Potassium chloride– Nitrate salts of alkali metals or alkaline earth metals

decompose to form metal nitrite and oxygen2NaNO3 (s) 2NaNO2(s) + O2(g)

2H2O2 (l) 2H2O(l) + O2(g)

– Hydrogen peroxide decompose to form water and oxygen

Decomposition ReactionsDecomposition Reactions3. Compound Compound + Compound

– decomposition of calcium carbonate produced a metal oxide and carbon dioxide

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– Solid hydroxides decompose to form a metal oxide and water vapor

– Ammonium salts lose ammonia

– Ammonium salt contains an anion that is strong oxidizing agent, its decomposition reaction produces an oxide, water and nitrogen gas.

CaCO3 (s) CaO(s) + CO2(g)

2Mg(OH)2 (s) MgO(s) + H2O (g)

(NH4) 2SO4 (s) 2NH3 (g) + H2SO4(l)

(NH4) 2Cr2O7 (s) Cr2O3 (s) + 4H2O (g) + N2 (g)

Displacement ReactionsDisplacement Reactions置換反應置換反應

• Displacement reactionsDisplacement reactions occur when one element displaces another element from a compound.– These are redox reactions in which the more active metal

displaces the less active metal of hydrogen from a compound in aqueous solution.

– Activity series is given in Table 4-14.

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Displacement ReactionsDisplacement Reactions1. [More Active Metal + Salt of Less Active Metal] [Less

Active Metal + Salt of More Active Metal]–molecular equation

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AgNO3 (aq) + Cu(s) Ag (s)+ CuNO3 (aq)


• Net ionic equation

Ag+ (aq) +NO3

2-(aq) +Cu(s) Cu+

(aq)+ NO3-(aq) +Ag(s)

Ag+ (aq)+Cu(s) Cu+

(aq)+ Ag(s)

Displacement ReactionsDisplacement Reactions2. [Active Metal + Nonoxidizing Acid] [Hydrogen + Salt of Acid]

– Common method for preparing hydrogen in the laboratory.– HNO3 is an oxidizing acid.

Molecular equation

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3H2SO4 (aq)+ 2Al(s) 3H2(g)+ Al2 (SO4)3 (aq)•Total ionic equation

6H+ (aq)+3SO4

2-(aq) +2Al(s) 2Al3+

(aq)+3SO42-

(aq) +3H2(g)•Net ionic equation

6H+ (aq)+2Al(s) 2Al3+

(aq)+3H2(g)

Displacement ReactionsDisplacement Reactions•The following metals are active enough to displace

hydrogen–K, Ca, Na, Mg, Al, Zn, Fe, Sn, & Pb

•Notice how the reaction changes with an oxidizing acid.

–Reaction of Cu with HNO3.• H2 is no longer produced.

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Displacement ReactionsDisplacement Reactions3. [Active Nonmetal + Salt of Less Active Nonmetal] [Less Active Nonmetal + Salt of More Active Nonmetal]• Molecular equation

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•Total ionic equation

Cl2(g)+2NaI(aq) I2(s)+2NaCl(aq)

Cl2 (g) +2Na+(aq)+ 2I-

(aq) 2Na+(aq)+2Cl-

(aq) + I2(s)

• Net ionic equationCl2 (g) +2I-

(aq) 2Cl-(aq) + I2(s)

Metathesis ReactionsMetathesis Reactions複分解反應複分解反應

• Metathesis reactionsMetathesis reactions occur when two ionic aqueous solutions are mixed and the ions switch partners.

AX + BY AY + BX• Metathesis reactions remove ions from solution in two

ways:1. form predominantly unionized molecules like H2O2. form an insoluble solid

• Ion removal is the driving force of metathesis reactions.

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Metathesis ReactionsMetathesis Reactions1. Acid-Base (neutralization) Reactions

– Formation of the nonelectrolyte H2O – acid + base salt + water

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• Molecular equation

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HBr (aq)+ KOH(aq) KBr(aq)+ H2O(l)



H+(g) +Br-

(aq)+ K+(aq)+OH-

(aq) K+(aq)+ Br-

(aq) + H2O(l)

H+(aq) +OH-

(aq) H2O(l)

Metathesis ReactionsMetathesis Reactions

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Ca(OH)2(aq)+2HNO3(aq) Ca(NO3) 2(aq)+ 2H2O(l)



Ca2+(aq) +2OH-

(aq)+ 2H+(aq)+2NO3

-(aq) Ca2+

(aq)+2NO-3(aq) +2 H2O(l)

H+(aq) +OH-

(aq) H2O(l)

Metathesis ReactionsMetathesis Reactions2.2. Precipitation reactionsPrecipitation reactions 沉澱沉澱 are metathesis

reactions in which an insoluble compound is formed.

– The solid precipitates out of the solution much like rain or snow precipitates out of the air.

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• Molecular equationCa(NO3)2 (aq)+K2CO3 (aq) 2KNO3(aq)+ 2CaCO3(s)



Ca2+(aq)+2NO3

- (aq)+ 2K+

(aq)+CO32-

(aq) 2K+(aq)+2NO-

3(aq) +CaCO3(s)

Ca2+(aq) +CO3

2-(aq) CaCO3(s)


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3CaCl2 (aq)+2Na2PO4 (aq) 6NaCl(aq)+ Ca3 (PO4)2(s)



3Ca2+(aq)+6Cl-

(aq)+ 6Na+(aq)+2PO4

3-(aq) 6Na+

(aq)+6Cl-(aq) +Ca3 (PO4)2(s)

3Ca2+(aq) +2PO4

3-(aq) Ca3 (PO4)2(s)


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2HCl (aq)+Na2SO3 (aq) 2NaCl(aq)+ H2O(l)+SO2(g)



2H+(aq)+2Cl-

(aq)+ 2Na+(aq)+SO3

2-(aq) 2Na+

(aq)+2Cl-(aq)+ H2O(l)+SO2(g)

2H+(aq) +SO3

2-(aq) H2O(l)+SO2(g)

Gas-Formation ReactionsGas-Formation Reactions• A gas-formation reaction is a type of reaction in which there

is a formation of an insoluble or slightly soluble gas when there are no gaseous reactants.

• Displacement reactions in which an active metal displaces from an acid or from water are gas-formation reactons; they are not methathesis reactions.

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Gas-Formation ReactionsGas-Formation Reactions• Consider hydrochloric acid with calcium carbonate to form

carbonic acid.

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Formula Unit2HCl(aq)+CaCO3 (s) H2CO3 (aq)+CaCl2 (aq)

Total Ionic2[H+

(aq)+Cl-(aq)] + CaCO3 (s) H2CO3 (aq) +[Ca2+

(aq) +2Cl-(aq)]

Net Ionic2H+

(aq) + CaCO3 (s) H2CO3 (aq) + Ca2+(aq)

• Enough heat is generated in the reaction to cause thermal decomposition of carbonic acid.

H2CO3 (aq) CO2(g) + H2O(l)

• The net effect of the chemical reaction and subsequent decomposition is2HCl(aq) + CaCO3 (s) CO2(g) + H2O(l) + CaCl2 (aq)

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Example 6-14 Classifying Reactions Classifying each of the following reactions.Example 6-14 Classifying Reactions Classifying each of the following reactions.

(a) Zn(s) + 2AgNO3 (aq) Zn(NO3)2(aq)+ 2Ag (s)(b) Ca(OH)2 (s) CaO(s)+ H2O(l)(c) 2HI (g) H2(g)+ I2(g)

Exercise 117-127

(d) Cu(NO3)2 (aq)+Na2S(aq) NaNO3(aq)+CuS(s)(e) SO2 (g)+H2O(l) H2SO3 (aq)(f) H2SO3 (aq)+2KOH(aq) K2SO3 (aq)+ 2H2O(l)

(a) Zn displace Ag displacement reaction Zn is oxidized and Ag is reduced Redox reaction (b) A simple compound breaks into two compounds decomposition reaction(c) A simple compound breaks into two elements decomposition reaction alsoRedox reaction (d) Two reactant compounds change partners metathesis reaction Insoluble CuS precipitation reaction (e) Two compounds combine to form a single product combination reaction (f) Change partners metathesis reaction acid-base react to form a salt and water acid-base (neutralization) reaction

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