organics I 4.5 Flashcards
what is crude oil
mixture of hydrocarbons
what happens to the colour of the fractions as the boiling point increases
darker
what happens to the viscosity of the fractions as the boiling point increases
become more viscous
how many fractions are there
6
what are fractions lowest bp - highest
refinery gases
gasoline
kerosene
diesel
fuel oil
bitumen
how does the molecular mass change as the boiling point increases
increases
use of refinery gases
fuel for home cooking
use of gasoline
fuel for cars
use of kerosene
fuel for aircraft
use of diesel
fuel for trains
use of fuel oil
fuel for ships
use of bitumen
making roads
how are fractions separated
fractional distillation
how does fractional distillation work
- heated crude oil vapours enter the column
- vapours rise until they reach their boiling point, when they condense
- different vapours condense at different heights due to their different boiling points
- similar vapours condense together as a fraction
how does temperature vary in the distillation column
the bottom is hot and the top is cooler
alkanes general formula
CnH2n+2
what are alkanes made from
simple molecules containing C and H atoms held together by covalent bonds
alkane 1 carbon name
methane
alkane 2 carbon name
ethane
alkane 3 carbon name
propane
alkane 4 carbon name
butane
alkane 5 carbon name
pentane
what is display formula
a diagram showing the position of every atom and every bond
what is structural formula
shows the structure of the molecule in one line
what is molecular formula
show show many carbon and hydrogen atoms there are
what is empirical formula
shows the simplest whole-number ratio
what is a homologous series
similar chemical reactions
trends in physical properties
same general formula
what is an isomer
a molecule with the same molecular formula but different structural formula
what makes isomers different
branching in the carbon chain
why are most alkanes used as fuels
they release a lot of energy when combusted
when does complete combustion occur
when there is excess oxygen
alkane + oxygen –>
carbon dioxide + water
when does incomplete combustion occur
when there isn’t enough oxygen
what does incomplete combustion release
carbon monoxide and soot
why do incomplete reactions make alkanes less useful
releases less energy
what does the combustion of alkanes as fuels release
carbon dioxide, nitrogen oxides, sulphur dioxide
how do alkanes react with halogens
swapping one hydrogen atom for one halogen atom
what type of reaction is it when a halogen reacts with an alkane
substitution reaction
what are the requirements for alkanes to react with halogens
UV light, as the alkane is not reactive
how does crude oil compare to other alkanes
much longer than shorter ones
what does cracking do
breaks down longer alkanes into smaller more useful ones
what conditions are needed for cracking
temperature - 650 degrees
catalyst - aluminium oxide
long alkane –>
shorter alkane + alkene
alkenes general formula
CnH2n
what is the difference between alkanes and alkenes
alkenes have one C=C double-bond
what does unsaturated mean
they have a double C=C bond
what does saturated mean
they don’t have a double C=C bond
are alkenes saturated or unsaturated
unsaturated
are alkanes saturated or unsaturated
saturated
what type of reaction is alkene + bromine
addition reaction
does an alkene +bromine reaction require uv light
no, alkenes are more reactive than alkanes
what colour does the mixture turn in an alkene + bromine reaction
orange –> colourless, bromine is used up in the reaction
when does an addition polymer form
when molecules with a C=C double bond add into chains
what are the small molecules that add together called
monomers
what are the long chains that form when added together called
polymers
how are addition polymers represented
repeating units
common uses for poly(ethene)
drinks bottles, shopping bags
common uses for poly(propene)
storage boxes, climbing ropes
common uses for poly(chloroethene)
wire insulation, drainpipes
poly(tetrafluoroethene)
non-stick coating
how to dispose of addition polymers
reuse, recycle, incinerate, landfill
how to dispose of addition polymers
reuse, recycle, incinerate, landfill
