1. 1 Announcements & Agenda (02/28/07) You should be reading Ch 10! …and Ch 11! Open review today @ 3pm! Quiz on Friday! Today 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)

2. 2 In the equation for neutralization, an acid and a base produce a salt and water. acid base salt water acid base salt water HCl + NaOH NaCl + H 2 O HCl + NaOH NaCl + H 2 O 2HCl + Ca(OH) 2 CaCl 2 + 2H 2 O 2HCl + Ca(OH) 2 CaCl 2 + 2H 2 O Last Time: Neutralization Equations Balance these like any other reaction!

3. 3 Last Time: Conjugate Acid-Base Pairs For ALL acid base reactions, there are 2 conjugate acid-base pairs. Each pair is related by the loss and gain of H +. Each 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 1 conjugate acid-base pair 1 HA + B A − + BH + HA + B A − + BH + conjugate acid-base pair 2

4. 4 Last Time: Buffers Buffer 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.

5. 5 Calculate the mL of 2.00 M H 2 SO 4 required to neutralize 50.0 mL of 1.00 M KOH. H 2 SO 4 (aq) + 2KOH(aq) K 2 SO 4 (aq) + 2H 2 O(l) 1) 12.5 mL 2) 50.0 mL 3) 200. mL 12345

6. 6 Solution 1)12.5 mL 0.0500 L KOH x 1.00 mole KOH x 1 mole H 2 SO 4 x 1 L KOH 2 mole KOH 1 L KOH 2 mole KOH 1 L H 2 SO 4 x 1000 mL = 12.5 mL 1 L H 2 SO 4 x 1000 mL = 12.5 mL 2.00 mole H 2 SO 4 1 L H 2 SO 4 2.00 mole H 2 SO 4 1 L H 2 SO 4

7. 7 Chapter 10: Introduction to Organic Chemistry - Alkanes

8. 8 Organic Chemistry An 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.

9. 9 Organic Compounds Typical 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 solvents.are soluble in nonpolar solvents. are usually not soluble in water.are usually not soluble in water. oil (organic) and water (inorganic)

10. 10 Organic vs. Inorganic Propane, C 3 H 8, is an organic compound used as a fuel.Propane, C 3 H 8, is an organic compound used as a fuel. NaCl, salt, is an inorganic compound composed of Na + and Cl - ions.NaCl, salt, is an inorganic compound composed of Na + and Cl - ions.

11. 11 Comparing Organic and Inorganic Compounds

12. 12 Alkanes (C n H 2n+2 )

13. 13 Some Properties of Alkanes Alkanes are nonpolar.nonpolar. insoluble in water.insoluble in water. less dense than water.less dense than water. flammable in air.flammable in air.

14. 14 Some Properties of Alkanes Alkanes with 1-4 carbon atoms are Alkanes with 1-4 carbon atoms are methane, ethane, propane, & butane.methane, ethane, propane, & butane. gases at room temperature.gases at room temperature. used as heating fuels.used as heating fuels.

15. 15 Some Properties of Alkanes Alkanes 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 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.

16. 16 Some Properties of Alkanes Alkanes with 18 or more carbon atoms have high molar masses.have high molar masses. are waxy solids at room temperature.are waxy solids at room temperature. used in waxy coatings of fruits and vegetables.used in waxy coatings of fruits and vegetables.

17. 17 Intermolecular Forces Intermolecular Forces Melting (blue) and boiling (pink) points of the first 14 n-alkanes in °C.

18. 18 Combustion In combustion reactions, alkanes react with oxygen.alkanes react with oxygen. CO 2, H 2 O and energy are produced.CO 2, H 2 O and energy are produced. Alkane + O 2 CO 2 + H 2 O + heat

19. 19 In organic compounds carbon has 4 valence electrons and hydrogen has 1.carbon has 4 valence electrons and hydrogen has 1. C H C H to achieve an octet, C forms four bonds.to achieve an octet, C forms four bonds. H H H H     H  C  H H C H     H H CH 4, methane H H CH 4, methane Writing Formulas of Alkanes

20. 20 Tetrahedral Structure of Carbon VSEPR theory predicts that a carbon atom with four single, covalent bonds, has a tetrahedral shape.

21. 21 Tetrahedral Structure of Carbon In molecules with two or more carbon atoms, each carbon atom with four single bonds has a tetrahedral shape.

22. 22 Names of Alkanes The names of alkanes are determined by the IUPAC (International Union of Pure and Applied Chemistry) system.are determined by the IUPAC (International Union of Pure and Applied Chemistry) system. end in –ane.end in –ane. with 1-4 carbons in a chain use prefixes as follows.with 1-4 carbons in a chain use prefixes as follows. Name # Carbons Structural Formula Methane1CH 4 Ethane2CH 3 CH 3 Propane3CH 3 CH 2 CH 3 Butane4CH 3 CH 2 CH 2 CH 3

23. 23 Names of Alkanes Alkanes with 5-10 carbon atoms in a chain use Greek prefixes. Name # Carbons Structural Formula Pentane 5 CH 3 CH 2 CH 2 CH 2 CH 3 Hexane 6 CH 3 CH 2 CH 2 CH 2 CH 2 CH 3 Heptane 7 CH 3 CH 2 CH 2 CH 2 CH 2 CH 2 CH 3 Octane 8 CH 3 CH 2 CH 2 CH 2 CH 2 CH 2 CH 2 CH 3 Nonane 9 CH 3 CH 2 CH 2 CH 2 CH 2 CH 2 CH 2 CH 2 CH 3 Decane 10 CH 3 CH 2 CH 2 CH 2 CH 2 CH 2 CH 2 CH 2 CH 2 CH 3

24. 24 Getting ziggy with it. Hexane is an alkane with six carbon atoms in a continuous chain.is an alkane with six carbon atoms in a continuous chain. has a “zig-zag” look because each carbon atom is at the center of a tetrahedron.has a “zig-zag” look because each carbon atom is at the center of a tetrahedron. is represented by a ball-and-stick model as shown below.is represented by a ball-and-stick model as shown below.

25. 25 Four Ways to Represent the Structures of Organic Compounds 4.Line Structures - See next slide 1. 2. 3.

26. 26 Help with Geometric (Line) Structures (Know how to draw these!!!) 1.All bonds except C-H bonds are shown as lines. 2.C-H bonds are NOT SHOWN on the line structure. 3.Single bonds are shown as single lines; double bonds are shown as 2 lines; triple bonds are shown as 3 lines. 4.Carbon atoms are not labeled. 5.ALL atoms EXCEPT carbon and hydrogen are labeled with their elemental symbols. 6.H atoms are labeled when they are attached to any atom other than carbon. Example: CH 3 -CH 2 -CH 2 -OH OH

27. 27 Cycloalkanes (C n H 2n ) are cyclic alkanes.are cyclic alkanes. have two hydrogen atoms fewer than the open chain.have two hydrogen atoms fewer than the open chain. are named by using the prefix cyclo- before the name of the alkane chain with the same number of carbon atoms.are named by using the prefix cyclo- before the name of the alkane chain with the same number of carbon atoms.

28. 28 Cycloalkanes The structural formulas of cycloalkanes are usually represented by geometric figures, CyclopropaneCyclobutane

29. 29 Isomers of Butane have the same molecular formula.have the same molecular formula. have different atom arrangements.have different atom arrangements. of butane (C 4 H 10 ) are a straight chain and a branched chain.of butane (C 4 H 10 ) are a straight chain and a branched chain.

30. 30 Alkyl 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 –yl ending.named with a –yl ending. H H C CH 3 methyl H H H H H H C C CH 3 CH 2 ethyl H H H H

31. 31 Naming Substituents In the IUPAC system, a carbon branch is named as an alkyl group.a carbon branch is named as an alkyl group. halogen atoms are named as halo.halogen atoms are named as halo. TABLE 10.6

32. 32 Naming Alkanes Give the name of CH 3 CH 3     CH 3 ─CH─CH─CH 3 CH 3 ─CH─CH─CH 3 STEP 1 Name the longest continuous chain. CH 3 CH 3 CH 3 CH 3     CH 3 ─CH─CH─CH 3 CH 3 ─CH─CH─CH 3butane

33. 33 Naming Alkanes Give the name of CH 3 CH 3     CH 3 ─CH─CH─CH 3 CH 3 ─CH─CH─CH 3 STEP 2 Number chain. CH 3 CH 3     CH 3 ─CH─CH─CH 3 CH 3 ─CH─CH─CH 3 1 2 3 4 1 2 3 4 STEP 3 Locate substituents and name. 2,3-dimethylbutane

34. 34 Learning Check Write the name of Cl CH 3 Cl CH 3     CH 3 ─CH 2 ─CH─CH─CH 3 CH 3 ─CH 2 ─CH─CH─CH 3

35. 35 Solution STEP 1 Longest chain is pentane. STEP 2 Number from end nearest substituent. Cl CH 3 Cl CH 3     CH 3 ─CH 2 ─CH─CH─CH 3 CH 3 ─CH 2 ─CH─CH─CH 3 5 4 3 2 1 5 4 3 2 1 STEP 3 Locate substituents and name alphabetically. 3-chloro-2-methylpentane