organic chem Flashcards
what are hydrocarbons
compounds that contain the elements of carbon and hydrogen only
what happens in an oil refinery
- petroleum ( crude oil) is made up of a mixture of hydrocarbons
- oil refineries separate the hydrocarbons in petroleum by fractional distillation
steps:
- the crude oil is heated and evaporates and enters the column which is cooler at the top and hotter at the bottom
- inside the column. each fraction condenses at a different temperature due to the fractions having different bp
- the smaller fractions with the lowest bp is condensed and removed at the top
- lager fractions depth highest bp is removed at the bottom
fraction and uses
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petroleum gases: fuel for cooking and heating
petrol (gasoline): fuel for car engines/motor vehicles
naphtha:
- feedstock (raw material) for petrolchemical industry (which produces plastics, detergents)
- usually cracked to produce lighter fractions
kerosene ( paraffin):
- fuel for aircraft engines
- fuel for cooking using oil stoves and for heating purposes
diesel: fuel for diesel engines (lorries/trucks)
lubricating oil:
- for lubricating machines
- for making waxes and polishes
bitumen: for paving/ making road surfaces
trends
as number of carbon atom per molecule increases,
- higher bp (molecules get larger and have stronger intermolecular forces of attraction which needs more energy to overcome)
- move viscous (larger molecules, more difficult to slide past)
- less flammable (larger molecules, more bonds to break before burning)
- burns with more smokey (darker) flame (higher % by mass of carbon)
alkanes: substitution with chlorine
- alkanes react with chlorine in the presence of ultraviolet light (photochemical reaction)
alkenes: cracking
- cracking is the process of breaking down long-chain alkanes into shorter chain alkanes and smaller alkenes or smaller alkenes and hydrogen with the use of a catalyst and high temperature
-catalyst used can be: aluminium oxide, silicon (IV) oxide, silicon dioxide or broken porous pot
alkenes addition reaction
- only one product formed
addition of hydrogen: veg oil + hydrogen -> margarine
- conditions: 200degC, nickel catalyst, hydrogen
- used to manufacture margarine (solid product) from unsaturated veg oil
addition of aq bromine:
- used to distinguish saturated (alkane) and unsaturated (alkene) compounds
- bubble alkanes ands alkenes separately into aq bromine
- alkanes: reddish brown aq bromine remains reddish brown
- alkenes: reddish brown aq bromine turns colourless rapidly
addition with steam:
- conditions: 500-600 degC, phosphoric (V) acid as catalyst
- alkenes + steam -> alcohol
definition of polyunsaturated
organic compound containing more than one carbon carbon double bond
alcohol
- hydroxyl group ( -O-H )
- volatile liquids
- low bp
- miscible in water
oxidation of alcohol
- alcohol + oxygen -> carboxylic acid + water
- enzymes in bacterial as catalyst
- OA acidified potassium manganate (VII) can be used to oxidase the alcohol under reflux conditions
fermentation of aq glucose solution to produce ethanol:
glucose solution -> ethanol + carbon dioxide
- conditions: absence of air to prevent oxidisation of ethanol produced into ethanol acid, yeast as enzymes catalyst and temperature of 37degC
esterifiucation
- conditions: little concentrated sulfuric acid used as catalyst and heat under reflux
isomerism
isomers are organic compounds having the same molecular formula but different structural formula
addition polymerisation
monomer: a small organic molecule that can be joined together covalently in large numbers to form long chain molecule (polymer)
polymer/macromolecule: a long chain molecule that is formed by joining many small molecules (monomers) together by covalent bonds
why does esterification need reflux
the esterification is slow and the starting reagents are volatile. to ensure they are well reacted and will not escape the flask before they finish reacting, reflux is required. the condenser will endure that any vapour that escapes will condense back and continue to react
