T6 Organic Chem Flashcards
hydrocarbons
compound containing only carbon and hydrogen
saturated
containing only single bonds
unsaturated
containing one or more multiple bonds
displayed formula
shows every atom and bond separately
structural formula
all atoms joined to a singular carbon are grouped
skeletal formula
only shows bonds between carbon atoms
molecular formula
shows numbers of each atom, not structure
empirical formula
molecular formula with each atom in its simplest whole-number ratio
functional group
an atom or group of atoms in a molecule that is responsible for its chemical reactions.
homologous series
family of compounds with the same functional group, differing by CH2.
they have similar chemical/physical properties displaying gradation.
alkane general formula
CnH2n+2
alkene general formula
CnH2n
halogenoalkane general formula
CnH2n+1X
alcohol general formula
CnH2n+1OH
structural isomers
compounds with the same molecular formula but differing structural formula
chain isomers
structural isomers with different carbon chains.
similar chemical properties but different physical.
position isomers
molecules with the same functional group attached in a different position on the same carbon chain
different physical/chemical properties
stereoisomerism
compounds with the same structural formula but with the atoms/groups arranged differently in 3 dimensions.
geometric isomers
compounds containing a CC double bond with atoms or groups attached at different positions.
bond angles shown on geometric isomers
at 120 degrees
trans
when the 2 Carbon groups are on opposite sides to one another.
cis
when the 2 carbon groups are on the same side to one another.
why do geometric isomers only occur at double bonds?
because the CC double bond presence restricts rotation so groups attached can’t move around
process of E/Z notation
- ) work out names of both isomers
- ) use priority rules as to which of 2 atoms on left of C=C has the higher priority (higher having a greater atomic number)
- ) copy on the right
- ) are they in the cis or trans positions?
E notation
equivalent of trans notation for non-carbons
Z notation
equivalent of cis notation for non-carbons
3 main processes used to convert crude oil into fuels
cracking
reforming
fractional distillation
fractional distillation
crude oil heated in furnace and passed into fractionating column in which there’s a temp gradient (hot at bottom and cooler at top), passing through column via a series of bubble caps, condensing at different heights, depending on bp.
larger molecules at bottom and smaller at top
cracking
hydrocarbons are passed over a heated catalyst (e.g zeolite/ aluminium oxide) causing them to break down.
why does reforming take place
as straight chains burn less efficiently than cyclic compounds so reforming occurs to convert straight chains into cyclic compounds
process of reforming
heating w a catalyst (eg. platinum)
complete combustion word equation
alkane + oxygen»_space; carbon dioxide + water
incomplete combustion word equation
alkane + oxygen»_space; carbon + carbon dioxide + water + carbon monoxide
what’s released in incomplete combustion?
soot
carbon monoxide (toxic replacement of oxygen in blood, colourless/odourless)
unburned hydrocarbons
how is sulfur dioxide formed?
effects on environment?
during alkane combustion, sulfur impurities react with oxygen in the air to form SO2 and further react in air to form sulfur trioxide.
both are acidic oxides and so dissolve in water to form sulphurous/ sulfuric acid.
nitrogen oxide formation
only under v high temps, nitrogen reacts in the air to form nitrogen oxides
these dissolve to form nitrous/nitric acid
catalytic converters
use metal meshes (eg, platinum, rhodium, palladium) to remove pollutants.
reactions that take place in catalytic converters
oxidation of carbon monoxide (2CO+O2»2CO2)
oxidation of unburned HC
Removal of nitrogen impurities
disadvantage of catalytic converter
poor at sulfur impurity removal so must be removed before is burnt
why do we need alternative fuels?
depletion of natural resources
global warming
biofuel
fuel obtained from living matter (that hasn’t died recently)
biodiesel
a fuel formed from vegetable oils obtained from plants