Organic Chemistry Flashcards
Examples of fossil fuels (3)
Petroleum (Crude oil)
Natural gas (mainly methane)
Coal
How is crude oil formed (2)
formed from remains of animals/plants pressed together under layers of rock
found underground + trapped between layers of impermeable rock
Where is Natural Gas found
trapped in pockets above crude oil
Features of fossil fuels (2)
non-renewable
valuable resource
Fractional Distillation in Petroleum/crude oil (4)
crude oil heated in furnace
passed into bottom of fractioning column
gives off mixture of vapours that rise up column
different fractions condense at different heights
Fractions at top of column (2)
light coloured liquid
runny liquid
Fractions at bottom of column (3)
dark
sticky
viscous - thick liquids that are not runny
Define hydrocarbon molecules (2)
molecules which contain only hydrogen and carbon
chemically bonded with covalent bonds but have different carbon atoms
Why is petroleum able to seperate
have different boiling points
longer hydrocarbon molecule = stronger intermolecular forces –> greater boiling point
Define petroleum
mixture of hydrocarbon molecules
Define volatile in terms of hydrocarbons
from vapour more easily
describes smaller molecule hydrocarbons
Shorter hydrocarbons burning features (3)
small flame
ignite easily
blue flame + almost no smoke
Longer hydrocarbon burning features (3)
large flame
difficult to light
yellow/smoky(grey) flame
Which hydrocarbon molecules are more useful? smaller ones or longer ones?
smaller
Catalytic cracking (2)
process to break down large hydrocarbon molecules into smaller ones
requires high temperatures between 600-700 degrees C + catalyst of silica or alumina
Features of homologous series (4)
have similar chemical properties
have same general formula
show gradual change in physical properties (e.g melting/boiling point)
differ from previous member of series by CH2
Define alkanes (4)
homologous series of organic molecules
hydrocarbons
made up of carbon atoms linked by a single covalent bond
known as saturated hydrocarbons
Where are alkanes obtained from
crude oil by fractional distillation
Smallest Alkenes (2)
used as fuels
relatively unreactive
Methane Alkane features (4)
CH4
H | H - C - H | H
boiling point of -162 degrees C
gas at room temperature/pressure
Ethane Alkane Features (4)
C2H6
H H | | H - C - C - H | | H H
boiling point of -89 degrees C
gas at room temperature/pressure
Butane Alkane Features (4)
C4H10
H H H H | | | | H - C - C - C - C - H | | | | H H H H
boiling point of 0 degrees celsius
gas at room temperature/pressure
Propane Alkane features (4)
C3H8
H H H | | | H - C - C - C - H | | | H H H
boiling point of -42 degrees C
gas at room temperature/pressure
Properties of alkanes (5)
CnH2n+2
saturated (no double C=C bond)
burn in oxygen to form CO2 + H2O (CO if limited supply of oxygen)
low reactivity - strong c-h bonds require lots of energy + hard to break
used as fuel
Alkane combustion in plentiful supply of air/oxygen (complete combustion) (3)
burn to form carbon dioxide + water
blue flame produced
alkane + 2O2 –> CO2 + 2H2O
Alkane combustion in limited supply of air/oxygen (incomplete combustion) (3)
forms carbon + water
yellow flame produced
alkane + O2 –> C + 2H2O
Alkane other incomplete combustion (2)
forms carbon monoxide + water (dangerous)
alkane + 3O2 –> 2CO + 4H2O
Carbon monoxide features (2)
no colour
no smell
Safety precautions for carbon monoxide (4)
service heaters or boilers regularly
ensure that jets aren’t blocked + limit air supply
ensure that exhaust flues aren’t blocked + allow carbon monoxide into room
flame should always be blue
Define alkenes (5)
homologous series
formed by catalytic cracking
unsaturated hydrocarbons - contain at least one carbon to carbon double bonds
burn well
reactive - due to carbon-to-carbon double bond
Ethene Alkene features (3)
C2H4
H H
\ /
C=C
/ \
H H
boiling point of -104 degrees C
gas at room temperature/pressure
Propene Alkene features (4)
C3H6
H H H H
\ / | /
H - C H or H - C - C=C
\ / | | \
C=C H H H
/ \
H H
boiling point of propene -48 degrees celsius
gas at room temperature/pressure