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Organic chemistry

Organic chemistry. BC Science Probe 10 Section 8.3. Organic Chemistry. Organic means living Hydrocarbons contain hydrogen and carbon atoms Organic Chemistry is the study of carbon chemicals that are natural and artificial.

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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

  8. Alcohols CnH2n+1OH • Functional group= OH CARBON OXYGEN MORE REACTIVE THAN: C-C C-H HYDROGEN OXYGEN

  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)

  20. FATTY ACID FATTY ACID FATTY ACID O GLYCEROL C H H O O O H-C-O-C-CH2-CH2..-CH3 H-C-O-C-CH2-CH2..-CH3 H-C- H-C- H-C- H-C- ESTER LINK

  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

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