organic chemistry
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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. - PowerPoint PPT PresentationTRANSCRIPT
BC Science Probe 10Section 8.3
Organic chemistry
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.
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!
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
CARBON HYDROGEN
UNREACTIVE BONDS
Properties1. Good fuels: - lots of heat energy made
- COMPLETE COMBUSTION H2O + CO2
- Short chains are best (cleaner + less energy to break)
2. Do not dissolve or react with water or reactants dissolved in water: - no energy to break the unreactive C-C or C-H bonds.
Examples:
C
H
H H
H
C
H
H
HH
C
H
H
Methane CH4
Ethane C2H6
• C=C is more reactive than C-C• The molecule is unsaturated and the double
bonds allow addition polymerisation.
Alkenes CnH2n
C C
HH
HHEthene C2H4
• Functional group= OH
Alcohols CnH2n+1OH
CARBON
HYDROGEN
OXYGEN
OXYGEN
MORE REACTIVE THAN:C-C C-H
Examples:
C
H
H
H
Methanol CH3OH
Ethanol C2H5OH
O H
C
H
H
HH
O HC
H
Physical Properties1. Forces between molecules are stronger than
between alkane molecules so alcohols are liquid at room temp.
2. Alcohol molecules have a tendency to stick together because they have OH, like water but not as much.
3. Short chains mix with water.
4. Long chains are oily because more CH than OH.
Chemical Properties
1. CH part burns CO2 + H2O
2. React with Na like water but slower:OH reacts and CH is inert.sodium + ethanol sodium ethanoxide + water
• Functional group= COOH• Made by oxidising Alcohols:
1. Alcohol heated with catalyst2. 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.
Organic Acids (Carboxylic) CnH2n-1COOH
Acids
Carboxylic Acids
MineralAcids
Examples Ethanoic (Acetic) Acid,Methanoic Acid,Propanoic Acid
Hydrochloric Acid, Nitric Acid, Sulphuric Acid
Fewer H+ ions (so weaker acids and safe for use in foods etc)
Lots of H+ ionsStrong acids
Acid + Water Hydrogen ions + Other ions
HCl + H2O H+ ions + Cl- ions
REACTIVITY
AlcoholsAlkenesAlkanes
C
H
H
HH
O HC
H
C
H
H
HH
C
H
H
C C
HH
HH
EthaneC2H6
EtheneC2H4
EthanolC2H5OH
Ethanoic AcidCH3COOH
C
H
H
H
O
C
HO
EstersOrganic 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
• Fruits• Plasticisers PVC• Soaps• Fats• Vegetable oils• Polyester• Laminates
MORE THAN ONE ESTER LINK
ESTER LINK
O
C
O
EsterificationEster + Alcohol Pure Ester Sample + Impurities
Esterification is this reaction when heated with some concentrated sulphuric acid to make a pure Ester.
1. Heated + reflux condenser2. Keep heating after reflux + impurities condense and out..3. Separating method: shaken alcohols, acids react with
aqueous reagents and dissolve but Ester does not.4. Calcium chloride crystals absorb moisture dry Ester5. Heat, only Ester evaporates and then condenses
PURE DRY ESTER
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 + AlcoholFats Fatty Acids + Glycerol (Alcohol)
O
C
O
ESTER LINK
H-C-O-C-CH2-CH2..-CH3
H-C-
H-C-
H O
H-C-O-C-CH2-CH2..-CH3
H-C-
H-C-
H O
Fats and OilsSaturated Fats Unsaturated Fats
Examples Animal Fats Vegetable Oils
State at room temp.
Solid Liquid
More H? Saturated: all single bonds, holds as much H as possible
Unsaturated: contains double bond, could take more H
Structure Straight chainRegular structure
Chains are not straightIrregular structure (does not solidify)
Health Saturated fats and trans fats are bad for you and can lead to heart disease
Unsaturated fats, omega fatty acids and CIS fats are good for you
MARGARINE:
Nickel catalyst
Vegetable oils Margarine
Unsaturated Saturated ( Heart Disease)
This is HYDROGENATIONHardening vegetable oils is cheaper than butter but it is just as harmful.
CIS Fats:Occur naturally is unsaturated fatty acids
Unsaturated2 parts of the chain on the same side of the double bond.
Trans Fats:More solid than CIS fatsStructure like saturated fatty acid Heart disease
Unsaturated2 parts of the chain on opposite sides of the double bond
Omega 3 Fatty AcidPOLYUNSATURATEFound in fishDouble bonds on every 3rd CarbonUnsaturated, good for jointsC-C-C=C-C-C=C-C-C=C
Omega 6 Fatty Acid POLYUNSATURATEFound in plant oilsDouble bonds on every 6th CarbonC-C-C-C-C-C=C-C-C-C-C-C=C
3 x Omega6 : 1x Omega3Essential part of a balanced diet