CHEM 3331 1nd Edition Lecture 5 Outline of Last Lecture I. Polarity of moleculesII. Supramolecular interactionsIII. SolubilityIV. Classes of organic compoundsOutline of Current Lecture I. Review of hydrocarbonsII. NomenclatureIII. Physical propertiesIV. Uses and sources of alkanesV. Reactions of alkanesCurrent LectureI. Review of HydrocarbonsHydrocarbons consist of subclasses: Alkanes, alkenes, alkynes, and aromatics.Alkanes are saturated hydrocarbons, this means they have toe absolute maximum hydrogens bonded to each carbon. Alkenes, alkynes, and aromatics are unsaturated hydrocarbons because they possess double and triple bonds. Homologous series, H-CH2-H, H-(CH2)2-H, H-(CH2)3-H.Can also be written as (CH2)nH2.The general formula is CnH2n+2 this applies regardless of branching or not.II. Nomenclature“Traditional nomenclature”- bottom names, “Modern/systematic nomenclature”- top names.These notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.IUPAC came up with a set of rules to give unambiguous name to alkanes.1) Find the longest chain of uninterrupted carbons; called the main chain. What is not part of the main chain is called a substituent. 2) The main chain with the most substituents is the correct one if a compound has 2 or more possibilities for a main chain3) Number main chain from side closest to first substituent4) Name and number substituents; CH3- methyl, CH3CH2CH2- propyl.5) If you have multiple substituents, order them alphabetically. If you hae more than one substituent of the same kind put them together.For example, The main chain is 7 carbons long; heptane. We have 3 methyl substituents and one ethyl subtituent. The methyls are found on carbons 2, 3, and 5. The ethyl is also found on 5. Thereforewe name this compound, 5-ethyl-2,3,5 trimethyl- heptane. Naming complex substituents: the carbon that connects to the main chain is called carbon 1. We find the longest chain and name it and take the substituent leftover and name it.For example, The bottom substituent consists of a propyl and a methyl. We order it alphabetically so it is 2-methyl propyl. The top substituent consists of a methyl and ethyl. This is called 1-ethyl methyl.III. Physical PropertiesNonpolar with single bonds between C-C and C-H.It is insoluble in water.Alkanes however are popular and widely used solvents.The density of alkanes is lighter than water and is around 0.7g/mL or lessCH4 boiling point is -164 ˚C whereas C10H22 boiling point is 174 ˚C.Boiling point rises with the addition of carbons because the surface area is increased and increases the contact surface between molecules. The line for boiling points of branched compounds is identical to that for linear compounds except it starts at lower temperatures sincebranched compounds have less surface area than linear compounds.Melting point increases as carbons are added however the curve is jagged almost like a staircase. IV. Alkanes uses and sourcesFound in fossil fuels and natural gas and oil. Oil is a complex mixture of liquid and solid alkanes. They refine oil to separate the mixture using distillation.C1-C2: used for liquefied natural gasC3-C4: camping fuel, replacement Freon C5-C8: gasolineC9-C16: jet and diesel fuelC16-C30: mineral oil and heating oilC25-C40: paraffin “wax”C40- : left as a residue at the bottom, put through additional processes and made into asphaltNatural gas is 70% methane. Used as a fuel for heating in houses. When its liquefied it becomes 100% methane. V. Reactions of Alkanesa) Combustion: CnH2n+2 + O2  nCO2 + (n+1)H2O + Eb) Cracking/ hydrocracking: C26H54 is split into C8H18 and C18H38 with the use of H2. There is a third reaction which will be covered in the next