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Organic chemistry

Organic chemistry

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Organic chemistry

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  1. Organic chemistry BC Science Probe 10 Section 8.3

  2. Organic Chemistry • Organic means living • Hydrocarbons contain hydrogen and carbon atoms • Organic Chemistry is the study of carbon chemicals that are natural and artificial. • The bonding in hydrocarbons is covalent so bonding between molecules is weak. • The structure is molecular.

  3. Percentage of Carbon • To be considered organic, a compound must have a high percentage of carbon by mass: • To calculate the percentage of carbon, you take the mass of carbon in the molecule divided by the mass of the whole molecule and multiply it by 100% • If it is higher than 50%, it’s organic!

  4. Alkanes CnH2n+2 • The bond between atoms are all single. • The bonds between atoms are strong but the bonds between molecules are weak. CARBON CARBON UNREACTIVE BONDS CARBON HYDROGEN

  5. Properties • Good fuels: - lots of heat energy made - COMPLETE COMBUSTION  H2O + CO2 - Short chains are best (cleaner + less energy to break) • Do not dissolve or react with water or reactants dissolved in water: - no energy to break the unreactive C-C or C-H bonds.

  6. H H H C C H H H H H H C H Examples: Methane CH4 Ethane C2H6

  7. H H C C H H Alkenes CnH2n • C=C is more reactive than C-C • The molecule is unsaturated and the double bonds allow addition polymerisation. Ethene C2H4


  9. H H C C H H H H O H C H Examples: H Methanol CH3OH O H Ethanol C2H5OH

  10. Physical Properties • Forces between molecules are stronger than between alkane molecules  so alcohols are liquid at room temp. • Alcohol molecules have a tendency to stick together because they have OH, like water but not as much. • Short chains mix with water. • Long chains are oily because more CH than OH.

  11. Chemical Properties • CH part burns  CO2 + H2O • React with Na like water but slower: OH reacts and CH is inert. sodium + ethanol  sodium ethanoxide + water

  12. Organic Acids (Carboxylic) CnH2n-1COOH • Functional group= COOH • Made by oxidising Alcohols: 1. Alcohol heated with catalyst 2. Reflux condenser used to vapours are not lost but drip back into the solution. 3.Organic acid collected. • The oxidation reaction is used in breathalyser tests • ethanoic acid  (in water) H+ and ethanoate ions ions This is reversible as the ions react and reform ethanoic acid.

  13. Acids Acid + Water  Hydrogen ions + Other ions HCl + H2O  H+ ions + Cl- ions

  14. REACTIVITY Alcohols Alkenes Alkanes

  15. H H C C H H H O H H H H H H H H C C C H O H C C C H O H H H H Ethanol C2H5OH Ethane C2H6 Ethanoic Acid CH3COOH Ethene C2H4

  16. Esters Organic Acid + Alcohol  Ester + Water This is a CONDENSATION REACTION as a molecule of water is lost. Alcohol loses OH and Acid loses H = H2O This is HYDROLYSIS because water is used to split the ester molecules. Sped up when heated &/or acid/alkali added

  17. O C O ESTER LINK • Fruits • Plasticisers  PVC • Soaps • Fats • Vegetable oils • Polyester • Laminates MORE THAN ONE ESTER LINK

  18. Esterification Ester + Alcohol  Pure Ester Sample + Impurities Esterification is this reaction when heated with some concentrated sulphuric acid to make a pure Ester. • Heated + reflux condenser • Keep heating after reflux + impurities condense and out.. • Separating method: shaken alcohols, acids react with aqueous reagents and dissolve but Ester does not. • Calcium chloride crystals absorb moisture  dry Ester • Heat, only Ester evaporates and then condenses  PURE DRY ESTER

  19. Fats and Oils • Fats and Oils have more than one Ester link in a single molecule. • Fats and Oils release 5 x more energy when oxidised than carbs. They are better energy store. Fats  Acids + Alcohol Fats  Fatty Acids + Glycerol (Alcohol)


  21. Fats and Oils

  22. MARGARINE: Nickel catalyst Vegetable oils  Margarine Unsaturated  Saturated ( Heart Disease) This is HYDROGENATION Hardening vegetable oils is cheaper than butter but it is just as harmful.

  23. CIS Fats: Occur naturally is unsaturated fatty acids Unsaturated 2 parts of the chain on the same side of the double bond. Omega 3 Fatty Acid POLYUNSATURATE Found in fish Double bonds on every 3rd Carbon Unsaturated, good for joints C-C-C=C-C-C=C-C-C=C Omega 6 Fatty Acid POLYUNSATURATE Found in plant oils Double bonds on every 6th Carbon C-C-C-C-C-C=C-C-C-C-C-C=C Trans Fats: More solid than CIS fats Structure like saturated fatty acid  Heart disease Unsaturated 2 parts of the chain on opposite sides of the double bond 3 x Omega6 : 1x Omega3 Essential part of a balanced diet