Organic “Carbon” Chemistry Chapter 13-14

1. Organic “Carbon” ChemistryChapter 13-14 Science 10 CT03D01 Resource: Brown, Ford, Ryan, IB Chem

2. Organic “Carbon” Chemistry • Chemistry for you, Lawrie Ryan • Chapter 13 • Pages 159-177 • Hydrocarbons, Fossil Fuels, Distillation of Crude Oil, Cracking, Plastics, Polymers • Chapter 14 • Pages 178-185 • Alcohols, Isomers, Ethanol, Alcohol Reactions, Carboxylic Acids

3. 13.1 - Hydrocarbons • A hydrocarbon is a compound containing only hydrogen and carbon • Crude Oil, which is very important to the survival Venezuela is a mixture of many hydrocarbons • Not only vital for fuels but also the starting materials for plastics and other polymers

4. 13.1 - Alkanes • The most common hydrocarbon found in crude oil is an alkane • An alkane contains a ‘backbone’ of single-bonded carbon atoms and is saturated with hydrogen atoms • Natural gas, methane, CH4, is the shortest alkane

5. 13.2 – Fossil Fuels • Most common fuels are fossil fuels • Coal, crude oil, natural gas, etc • Coal, although it’s not a hydrocarbon, does contain carbon and hydrogen, as well as oxygen in some of it’s molecules • From organic material (like trees) that died and were buried below swamps • Crude oil, hydrocarbons • Formed from tiny animals and plants which lived in the sea • Takes millions of years to form fossil fuels • In reality the energy comes from the sun to produce fossil fuels, but it simply takes so long to produce

6. 13.2 – Finding Oil • Crude oil today was made from mainly plankton that died about 150 million years ago. Their bodies did not decay normally due to lack of oxygen and with high pressures and temperatures, formed oil and natural gas. • We can find oil by surveying the land and it’s topography • Look for dome shaped layers (cap rock or anti-cline) • Seismic survey

7. 13.3 – Distilling Crude Oil • When crude oil reaches the refinery it’s a thick, black, and smelly liquid • This liquid contains long hydrocarbon chains • At the refinery the long chains can be sorted out into groups of useful substances called fractions • We can separate these substances by fractional distillationwhich separates substances based on their boiling point

8. 13.4 – Fractional Distillation in Industry

9. 13.5 - Cracking • After distillation of crude oil companies are still left with long hydrocarbons and the need is for shorter chains like petrol • The solution is cracking meaning big molecules are broken down by heating them over a catalyst • This is competed inside a cracker

10. 13.6 - Plastics • When oil companies crack large molecules into smaller ones, ethene is made • Ethene is just like ethane, but with a double bond making it unsaturated • This ethene molecule is the starting material for plastics. When the double bond is broken, new bonds can form between several molecules forming polymers • Lots of small, reactive molecules called monomers join together to make a polymer vs ethene

11. 13.7 – Ethene and the Alkenes • Alkenes, which are also hydrocarbons, are very similar to alkanes, but are not saturated. They have at least one double bond and less hydrogen atoms which makes them unsaturated. • Their names end in –ene instead of –ane • Contain double bonds • Very reactive • Building block for polymers • Also react with • Br, Cl, I, F water • Strong acids • Water and sulfuric adid

12. 13.8 - Polymerization • There are two types of reactions that make polymers • Addition – where at least two things simply join together • Condensation – where water is given off in the process of joining molecules. Also known as dehydration synthesis

13. 13.8 – Addition Polymerization • Addition Reactions • Monomers have at least one double bond • The polymer is the only material formed in the reaction • Easiest example is ethene used to make poly(ethene) • n C2H4 -[-C2H4-]-n • Where n = large number • The double bonds open up to form single bonds to the adjacent monomer R can be just about anything

14. 13.9 – Condensation Polymerization • Nylon is an example of a polymer formed through condensation • Fumes are given off as the different monomers react together. These small molecules given off could be H2O, HCl, etc. It depends on the ends of the monomers. • The monomers have reactive parts at both ends and join end-to-end to make long chain polymers + H2O

15. 13.10 – Properties of Plastics • Many materials are made out of plastics • PVC piping, bags, surfaces, protective films, bottles, etc • Plastics often have advantages over the use of metal compounds and cost much less • When we run out of oil we will also run out of access to cheap plastics • This is why recycling our plastics is so important!!

16. Chapter 14 – Organic Molecules • Nomenclature! • How do we name organic compounds? • Alkane vs alkene • Saturated vs unsaturated • Functional groups • Length of chain

17. 14.1 – Types of Organics

18. 14.2 - Members of Homologous Series • Differ by a CH2 • Can be represented by the same general formula • Show gradation in physical properties • Have similar chemical properties

19. 14.2 - Members of Homologous Series…… differ by a –CH2 group

20. 14.2 - Members of Homologous Series…… can be represented by the same general formula

21. 14.2 - Members of Homologous Series…… show gradation in physical properties • Since the series differ by one –CH2 they have successively longer carbon chains • Results in gradual trend of phy. Props • Not always a linear growth • Density and viscosity are other examples

22. 14.2 - Members of Homologous Series…… show similar chemical properties • As the have the same functional group • Ex.1 – the alcohols have a functional –OH group, which can be oxidized to form organic acids • Ex. 2 – the –COOH functional group, present in the homologous series of the carboxylic acids, is responsible for the acidic properties of these compounds

23. 14.3 – Organic Formulas • Emperical formula • Simplest whole number ratio • Ethane CH3 • Molecular formula • Actual number of atoms • Ethane C2H6 • Structural Formula • Full, condensed, steriochemical

24. 14.3 - Emperical Formula • The simplest whole number ratio of the atoms it contains. For example, the emperical formula of ethane, C2H6, is CH3. This formula can be derived from percentage composition data obtained from combustion analysis. It is, however, of rather limited use on it’s own, as it does not tell us the actual number of atoms in the molecule.

25. 14.3 - Molecular Formula • Actual number of atoms of each element present. For example, the molecular formula of ethane is C2H6. It is therefore a multiple of the emperical formula, and so can be deduced if we know both the emperical formula and the relative molecular mass Mr.

26. 14.3 - Full Structural Formula • Graphic formula or displayed formula – shows every bonded atom. Usually 90o and 180o angles are used to show the bonds because this is the clearest 2-D representation, although it is not the true geometry of the molecule

27. 14.3 - Condensed Structural Formula • Often omits bonds where they can be assumed, and groups atoms together. It contains the minimum information needed to describe the molecule non-ambiguously – in other words there is only one possible structure that could be described by its formula.

28. 14.4 – IUPAC Nomenclature • Nomenclature for Organic Compounds: the IUPAC system • International Union of Pure and Applied Chemistry • Rule 1: Identify the longest straight chain of carbons • Rule 2: Identify the functional group • Rule 3: Identify the side chains or substituent groups

29. 14.4 - IUPAC Rule 1: Longest Chain Note: ‘straight chain’ does not mean just 180o angles or unbranched chains of carbon atoms. Be careful, do not be confused by the way the molecule may appear on paper because of free rotation around the carbon-carbon single bonds. Example, all three below are the same….

30. 15.4 - IUPAC Rule 2: Functional Group • The functional group is described by a specific ending (or suffix) to the name, that replaces the –ane ending of the name of the parent alkane. The suffixes used for some common functional groups are in the slides to follow. Those marked * will have slides with further information.

31. 14.4 - Functional Groups

32. 14.4 - IUPAC Rule 3: Side Chains

33. 14.5 - Structural Isomers • Different arrangements of the same atoms make different molecules • Molecular formula shows the atoms that are present in a molecule, but gives no information on how they are arranged. Consider, for example, C4H10 • Each isomer is a distinct compound, having unique physical and chemical properties.

34. 14.5 - Structural Isomers of Alkenes

35. 14.6 - Alkanes as Fuels • Release significant amounts of energy when they burn, highly exothermic, because large amount of energy released when forming.. • Double bonds of CO2 • Bonds in H2O C3H8 + 5O2 3CO2 + 4H2O ΔH = -2200 kJ/mol However, when O2 is limited….. 2C3H8 + 7O2 6CO + 8H2O when O2 is extremely limited….. C3H8 + 2O2 3C + 4H2O These are examples of the incomplete combustion of fossil fuels which makes them an environmental concern