Announcements & Agenda (02/28/07)

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AnnouncementsAnnouncements & Agenda& Agenda (02/28/07)(02/28/07)

You should be reading Ch 10! …and Ch 11!You should be reading Ch 10! …and Ch 11!Open review today @ 3pm!Open review today @ 3pm!Quiz on Friday!Quiz on Friday!

TodayToday Introduction to Organic Chemistry (10.1)Introduction to Organic Chemistry (10.1) Alkanes (10.2), Properties of Alkanes (10.4)Alkanes (10.2), Properties of Alkanes (10.4) Substituents (10.3)Substituents (10.3)

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In the equation for neutralization, an acid In the equation for neutralization, an acid and a base produce a salt and water.and a base produce a salt and water. acidacid base base saltsalt waterwater

HCl + NaOH NaCl + HHCl + NaOH NaCl + H22OO

2HCl + Ca(OH)2HCl + Ca(OH)22 CaCl CaCl22 + 2H + 2H22OO

Last Time: Neutralization EquationsLast Time: Neutralization Equations

Balance these like any other reaction!

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Last Time: Conjugate Acid-Base PairsLast Time: Conjugate Acid-Base Pairs

For ALL acid base reactions, there are 2 conjugate For ALL acid base reactions, there are 2 conjugate acid-base pairs.acid-base pairs.

• Each pair is related by the loss and gain of HEach pair is related by the loss and gain of H+ + ..• One pair occurs in the forward direction.One pair occurs in the forward direction.• One pair occurs in the reverse direction.One pair occurs in the reverse direction.

conjugate acid-base pair 1conjugate acid-base pair 1

HA + B AHA + B A− − + BH+ BH++

conjugate acid-base pair 2conjugate acid-base pair 2

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Last Time: BuffersLast Time: BuffersBuffer action occurs asBuffer action occurs as• the weak acid in a buffer neutralizes base.the weak acid in a buffer neutralizes base.• the conjugate base in the buffer neutralizes acid. the conjugate base in the buffer neutralizes acid. • the pH of the solution is maintained.the pH of the solution is maintained.

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Calculate the mL of 2.00 M HCalculate the mL of 2.00 M H22SOSO44 required to required to neutralize 50.0 mL of 1.00 M KOH. neutralize 50.0 mL of 1.00 M KOH. HH22SOSO44((aqaq) + 2KOH() + 2KOH(aqaq) K) K22SOSO44((aqaq) + 2H) + 2H22O(O(ll))

0%

0%

0% 1) 12.5 mL1) 12.5 mL

2) 50.0 mL2) 50.0 mL

3) 200. mL3) 200. mL

11 22 33 44 55

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SolutionSolution

1)1) 12.5 mL12.5 mL 0.0500 L KOH x 0.0500 L KOH x 1.00 mole KOH1.00 mole KOH x x 1 mole H 1 mole H22SOSO44 x x

1 L KOH1 L KOH 2 mole KOH 2 mole KOH 1 L H1 L H22SOSO44 x x 1000 mL1000 mL = 12.5 mL = 12.5 mL

2.00 mole H2.00 mole H22SOSO44 1 L H 1 L H22SOSO44

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Chapter 10: Introduction to Chapter 10: Introduction to Organic Chemistry - AlkanesOrganic Chemistry - Alkanes

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Organic ChemistryOrganic Chemistry

An organic compoundAn organic compound

• is a compound made from carbon atoms.is a compound made from carbon atoms.• has one or more C atoms. has one or more C atoms. • has many H atoms.has many H atoms.• may also contain O, S, N, and halogens.may also contain O, S, N, and halogens.

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Organic CompoundsOrganic Compounds

Typical organic compoundsTypical organic compounds

• have covalent bonds.have covalent bonds.• have low melting points.have low melting points.• have low boiling points.have low boiling points.• are flammable.are flammable.• are soluble in nonpolar are soluble in nonpolar

solvents.solvents.• are usually not soluble in are usually not soluble in

water.water.oil (organic) and water (inorganic)

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Organic vs. InorganicOrganic vs. Inorganic

• Propane, CPropane, C33HH88, is an , is an organic compound used organic compound used as a fuel.as a fuel.

• NaCl, salt, is an NaCl, salt, is an inorganic compound inorganic compound composed of Nacomposed of Na++ and Cl and Cl-- ions. ions.

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Comparing Organic and Inorganic Comparing Organic and Inorganic CompoundsCompounds

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Alkanes (CAlkanes (CnnHH2n+22n+2))

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Some Properties of AlkanesSome Properties of Alkanes

Alkanes areAlkanes are• nonpolar.nonpolar.• insoluble in water.insoluble in water.• less dense than water.less dense than water.• flammable in air.flammable in air.

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Alkanes with 1-4 Alkanes with 1-4 carbon atoms arecarbon atoms are

• methane, ethane, methane, ethane, propane, & butane.propane, & butane.

• gases at room gases at room temperature.temperature.

• used as heating used as heating fuels.fuels.

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Some Properties of AlkanesSome Properties of AlkanesAlkanes with 5-8 carbon atoms areAlkanes with 5-8 carbon atoms are• liquids at room temperature.liquids at room temperature.• pentane, hexane, heptane, and octane.pentane, hexane, heptane, and octane.• very volatile.very volatile.• used to make gasoline.used to make gasoline.

Alkanes with 9-17 carbon atomsAlkanes with 9-17 carbon atoms • are liquids at room temperatureare liquids at room temperature• have higher boiling points.have higher boiling points.• are found in kerosene, diesel, and jet fuels.are found in kerosene, diesel, and jet fuels.

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Alkanes with 18 or Alkanes with 18 or more carbon atomsmore carbon atoms

• have high molar have high molar masses.masses.

• are waxy solids at are waxy solids at room temperature.room temperature.

• used in waxy used in waxy coatings of fruits and coatings of fruits and vegetables.vegetables.

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Intermolecular Forces Intermolecular Forces

Melting (blue) and boiling (pink) points of the first 14 n-alkanes in °C.

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CombustionCombustion

In combustion reactions,In combustion reactions,

• alkanes react with oxygen.alkanes react with oxygen. • COCO22, H, H22O and energy are O and energy are

produced.produced.

Alkane + OAlkane + O22 CO CO22 + H + H22O + heatO + heat

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In organic compounds In organic compounds • carbon has 4 valence electrons and hydrogen has 1. carbon has 4 valence electrons and hydrogen has 1.

••

•• C C • H •• H • ••

• to achieve an octet, C forms four bondsto achieve an octet, C forms four bonds. . HH H H

H H C C H H H C H H C H HH H H CHCH4 4 , methane, methane

Writing Formulas of AlkanesWriting Formulas of Alkanes

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Tetrahedral Structure of CarbonTetrahedral Structure of Carbon

VSEPR theoryVSEPR theory predicts that a predicts that a carbon atom carbon atom with four single, with four single, covalent bonds, covalent bonds, has a has a tetrahedral tetrahedral shape.shape.

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Tetrahedral Structure of CarbonTetrahedral Structure of Carbon

In molecules with In molecules with two or more two or more carbon atoms, carbon atoms, each carbon each carbon atom with four atom with four single bonds has single bonds has a tetrahedral a tetrahedral shape.shape.

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Names of AlkanesNames of AlkanesThe names of The names of alkanesalkanes • are determined by the IUPAC (International Union of Pure are determined by the IUPAC (International Union of Pure

and Applied Chemistry) system.and Applied Chemistry) system.• end in end in ––aneane..• with 1-4 carbons in a chain use prefixes as follows.with 1-4 carbons in a chain use prefixes as follows.

NameName # Carbons # Carbons Structural FormulaStructural Formula

MethMethaneane 11 CCHH44

EthEthaneane 22 CCHH33CCHH33

PropPropaneane 33 CCHH33CCHH22CCHH33

ButButaneane 44 CCHH33CCHH22CCHH22CCHH33

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Names of AlkanesNames of Alkanes

Alkanes with 5-10 carbon atoms in a chain use Greek prefixes.Alkanes with 5-10 carbon atoms in a chain use Greek prefixes.NameName # Carbons # Carbons Structural FormulaStructural Formula

PentPentane 5ane 5 CH CH33CHCH22CHCH22CHCH22CHCH33

HexHexane 6 CHane 6 CH33CHCH22CHCH22CHCH22CHCH22CHCH33

HeptHeptane 7 CHane 7 CH33CHCH22CHCH22CHCH22CHCH22CHCH22CHCH33

OctOctane 8 CHane 8 CH33CHCH22CHCH22CHCH22CHCH22CHCH22CHCH22CHCH33

NonNonane 9 CHane 9 CH3 3 CHCH2 2 CHCH22CHCH22CHCH22CHCH22CHCH22CHCH22CHCH33

DecDecane 10 CHane 10 CH33CHCH22CHCH22CHCH22CHCH22CHCH22CHCH22CHCH22CHCH22CHCH33

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Getting ziggy with it.Getting ziggy with it. Hexane Hexane • is an alkane with six carbon atoms in a is an alkane with six carbon atoms in a

continuous chain.continuous chain.• has a “zig-zag” look because each carbon has a “zig-zag” look because each carbon

atom is at the center of a tetrahedron.atom is at the center of a tetrahedron.• is represented by a ball-and-stick model as is represented by a ball-and-stick model as

shown below.shown below.

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Four Ways to Represent the Structures of Four Ways to Represent the Structures of Organic CompoundsOrganic Compounds

4. Line Structures- See next slide

1.

2.

3.

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Help with Geometric (Line) StructuresHelp with Geometric (Line) Structures(Know how to draw these!!!)(Know how to draw these!!!)

1.1. All bonds except C-H bonds are shown as lines.All bonds except C-H bonds are shown as lines.2.2. C-H bonds are C-H bonds are NOT SHOWNNOT SHOWN on the line structure. on the line structure.3.3. Single bonds are shown as single lines; double bonds are Single bonds are shown as single lines; double bonds are

shown as 2 lines; triple bonds are shown as 3 lines.shown as 2 lines; triple bonds are shown as 3 lines.4.4. Carbon atoms are not labeled.Carbon atoms are not labeled.5.5. ALLALL atoms atoms EXCEPTEXCEPT carbon and hydrogen are labeled with carbon and hydrogen are labeled with

their elemental symbols.their elemental symbols.6.6. H atoms are labeled when they are attached to any atom H atoms are labeled when they are attached to any atom

other than carbon.other than carbon.

Example: CHExample: CH33-CH-CH22-CH-CH22-OH OH-OH OH

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Cycloalkanes (CCycloalkanes (CnnHH2n2n))

• are cyclic alkanes.are cyclic alkanes.

• have two hydrogen atoms fewer than the have two hydrogen atoms fewer than the open chain.open chain.

• are named by using the prefix are named by using the prefix cyclocyclo-- before the name of the alkane chain with before the name of the alkane chain with the same number of carbon atoms.the same number of carbon atoms.

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CycloalkanesCycloalkanes

The structural formulas of cycloalkanes are usually The structural formulas of cycloalkanes are usually

represented by geometric figures,represented by geometric figures,

CyclopropaneCyclopropane

CyclobutaneCyclobutane

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Isomers of ButaneIsomers of Butane

• have the same have the same molecular formula.molecular formula.

• have different atom have different atom arrangements.arrangements.

• of butane (Cof butane (C44HH1010) ) are a straight chain are a straight chain and a branched and a branched chain. chain.

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Alkyl groupsAlkyl groups • alkanes that are missing one H. alkanes that are missing one H. • substituents attached to carbon chains.substituents attached to carbon chains.• named with a named with a –yl–yl ending. ending.

HH

H CH C CH CH33 methylmethyl

HH H HH H H C CH C C CH CH33 CHCH22 ethylethyl H HH H

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Naming SubstituentsNaming Substituents

In the IUPAC In the IUPAC system,system,

• a carbon branch a carbon branch is named as an is named as an alkyl group.alkyl group.

• halogen atoms halogen atoms are named as are named as halo.halo.

TABLE 10.6

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Naming AlkanesNaming AlkanesGive the name of CHGive the name of CH3 3 CHCH33

CHCH33─CH─CH─CH─CH─CH─CH33

STEP 1 STEP 1 Name the longest continuous chain.Name the longest continuous chain. CHCH3 3 CHCH33


butanebutane

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Naming AlkanesNaming AlkanesGive the name of CHGive the name of CH3 3 CHCH33


STEP 2 STEP 2 Number chain.Number chain. CHCH3 3 CHCH33


1 2 3 41 2 3 4STEP 3 STEP 3 Locate substituents and name. Locate substituents and name.

2,3-dimethyl2,3-dimethylbutanebutane

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Learning CheckLearning Check

Write the name ofWrite the name of

ClCl CHCH33

CHCH33─CH─CH22─CH─CH─CH─CH─CH─CH33

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SolutionSolutionSTEP 1STEP 1 Longest chain is Longest chain is pentanepentane..

STEP 2 STEP 2 Number from end nearestNumber from end nearest substituent.substituent.

ClCl CHCH33

CHCH33─CH─CH22─CH─CH─CH─CH─CH─CH33

5 4 3 2 15 4 3 2 1

STEP 3STEP 3 Locate substituents and name alphabetically. Locate substituents and name alphabetically. 3-chloro-2-methyl3-chloro-2-methylpentanepentane

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Announcements & Agenda (02/28/07)