organic chemistry ⚗ Flashcards
what are hydrocarbons?
compound which contain only carbon and hydrogen
what are organic compounds?
compounds which contain carbon, hydrogen, oxygen…
what is a homologous series?
a family of organic compounds with the same functional group and similar chemical properties. they have the same general formula and successive members differ by a -CH2- group
trends of physical properties down a homologous series
1) melting and boiling points increases down the series
2) viscosity of liquid increases down the series
3) flammability decreases down the series and they burn with a more sooty flame
why do melting and boiling points increase down the series?
down the group, relative molecular mass increases and more energy is required to overcome the stronger intermolecular forces of attraction between larger molecules, hence melting and boiling points increase
why does viscosity increase down the series?
down the series, liquid flows less easily due to stronger electrostatic forces of attraction between larger molecules, hence viscosity increases
why do compounds burn with a more sooty flame down the series?
the percentage of carbon content in the compound increases down the group, hence the compound burns with a more sooty flame
order of fractional distillation of petroleum
1) petroleum gas
2) petrol
3) naphtha
4) kerosene
5) diesel
6) lubricating oil
7) bitumen
use of petroleum gas
cooking
use of petrol
fuel for car engines
use of naphtha
feedstock for the petrochemical industry
use of kerosene
fuel for aircraft engines, cooking using oil stoves
use of diesel
fuel for diesel engines
use of lubricating oil
making waxes and polishes
use of bitumen
for paving road surfaces
what is catalytic cracking and its conditions?
the process of breaking down long-chain hydrocarbons into shorter chain hydrocarbons by passing the hot vapourised hydrocarbons over a heated catalyst
- aluminium oxide and silicon oxide as catalysts at 600°C
what is the importance of cracking?
converts long-chain hydrocarbons high in supply low in demand to shorter-chain hydrocarbons high in demand but low in supply
alkanes general formula and functional group
CnH2n+2, no functional group
define isomer
molecules with same molecular formula but different structural formula
chemical reactions of alkanes
1) combustion
2) substitution reaction: direct replacement of hydrogen with a halogen one atom by one atom (in presence of ultraviolet light)
alkenes general formula and functional group
CnH2n, C=C functional group
chemical reactions of alkenes
1) combustion
2) addition of hydrogen (hydrogenation)
- addition of hydrogen across C=C to form alkanes; 180°C, nickel as a catalyst
3) addition of bromine
- orange aqueous bromine decolourises rapidly; presence of ultraviolet light
4) addition of steam (hydration)
- addition of steam across C=C to form alcohols; 300°C, 65atm, phosphoric acid as a catalyst
5) addition polymerisation
- open up the C=C bonds; high temperature and pressure, presence of catalyst
similarities between alkanes and alkenes
- both are hydrocarbons
- both undergo combustion reactions
differences between alkanes and alkenes
- alkenes are unsaturated, alkanes are saturated
- alkenes reactive, alkanes unreactive
- alkenes burn with a more sooty flame
- all the alkene reactions
alcohols general formula and functional group
general formula CnH2n+1OH, functional group hydroxyl group -OH
chemical reactions of alcohols
1) combustion
2) oxidation
- alcohols oxidised to form carboxylic acids, by atmospheric oxygen or oxidising agents; heat with oxidising agents
3) dehydration
- water is removed to form alkenes; 170°C with concentrated sulfuric acid as a dehydrating agent
manufacture of alcohols
1) hydration of alkenes
2) fermentation of glucose
- yeast, absence of oxygen, best at 37°C
carboxylic acids general formula and functional group
general formula CnH2n+1COOH where n = 0,1.., functional group carboxyl group -COOH
chemical reactions of carboxylic acids
1) all acid reactions: metal, metal carbonate, alkalis/bases
2) esterification
- reaction with alcohols to form esters with the removal of water; heat under reflux with concentrated sulfuric acid as a catalyst
what is the name of CH3CH2CH2COOCH3?
methyl butanoate
process of condensation polymerisation
monomers join together to form a polymer with the removal of water
peptide linkage
O=C-N-H
ester linkage
O=C-O
differences between addition and condensation polymerisation
- addition have unsaturated monomers, condensation have monomers with two functional groups (di-)
- addition polymer has the same empirical formula as monomer, condensation doesn’t
- addition no side products produced, condensation water produced
