organics Flashcards
what is a hydrocarbon?
a compound containing only hydrogen and carbon atoms
in what ways can organic compounds be represented in?
empirical formula, molecular formula, general formulae, structural formulae and condenses structural formulae
what does the empirical formula show?
the simplest possible ratio of the atoms in a molecule
what does the molecular formula show?
the actual number of atoms in a molecule
(basically the relationship between carbon and hydrogen atoms)
what does the general formula show?
a ratio of atoms in a family of compounds in terms of n where n is a varying whole number
what is the general formula for an alkANE
cn H2n+2
what is the displayed formula( also known as the graphical formula?)
the spatial arrangement of all the atoms and bonds in a molecule
what does a structural formula show?
the clear structure, the important bonds (double and triple bonds), side groups and straight chain alkanes
what is a homologous series?
a series or family of organic compounds that have similar features and chemical properties due to them having the same functional group
all members of a homologous series have?
the same general formula, same functional group, similar chemical properties, gradation in their physical properties and the difference in the molecular formula between one member and the next is CH2
what is a functional group?
a group of atoms bonded in a specific arrangement that influences the properties of the homologous series
what is a isomer?
compounds that have the same molecular formula but different displayed formulae
example of an isomer?
propane and cyclopropane
what does the prefix of an organic compound tell you?
how many carbon atoms are present in the longest continuous chain in the compound
what does the suffix tell you?
what functional group is on the compound
monkeys….
eat peanut butter properly!
what can the reactions of organic compounds be classified into?
substitution, addition and combustion
what is a substitution reaction?
when one functional group is replaced by another
what is an addition reaction?
takes place when 2 or more molecules combine to form a larger molecule with no other products
what is combustion
the scientific term for burning
what happens in a combustion reaction?
an organic substance reacts with oxygen to form carbon dioxide (or carbon monoxide if incomplete combustion) and water
when do alkENES burn?
when heated in air or oxygen
if there is an unlimited supply of air/oxygen the products are what? (combustion)
carbon dioxide and water
if there is a limited supply of air/oxygen what are the products?
carbon monoxide and water
what is crude oil?
a mixture of hydrocarbons of different chain lengths
how can crude oil be separated into useful fractions?
fractional distillation
what does each fraction contain?
a hydrocarbon of similar lengths and similar boiling points
how is crude oil formed?
from dead organisms buried by sedimentation
is crude oil renewable or non renewable?
non renewable because we are using it up faster than it is formed
what is the first stage of fractional distillation?
crude oil is vaporised- heated to high temperatures, usually above 350 degrees
the vapours are fed into what?
a fractionating column
the fractionating column has a temperature gradient which means what?
it’s hotter at the bottom and cooler at the top
when do the gases condense?
when they reach their boiling point
the different fractions are collected as what at different levels?
liquids
bitumen usage?
roads and roofs
fuel oil usage?
fuel for ships and power stations
diesel usage?
fuel for cars, lorries and buses
kerosene usage?
aircraft fuel
gasoline usage?
fuel for cars
refinery gases usage?
bottled gas
the fractions collected at the bottom of the column contain what type of molecules?
molecules with a large number of carbon atoms in a long chain
which gas contains the smallest molecules?
refinery gases- contains only a few carbon atoms in short chains
as you go up the column what happens to the chain length and volatility?
decreasing chain length and higher volatility
what does the small molecules being very volatile mean?
they evaporate very easily
long chain hydrocarbons have low or high boiling points?
high boiling points
does the boiling point increase or decrease with chain length?
increases- larger the hydrocarbon the higher the boiling point
the fractions collected nearer the bottom are darker or lighter in colour?
darker in colour and are thick and sticky
the fractions at the bottom have a high or low viscosity?
high viscosity
the fractions nearer the top are lighter or darker in colour?
lighter and they flow more easily
the fractions near the top have a lower or higher viscosity?
lower viscosity
a hydrocarbon will vaporise at its boiling point and also what?
condense to a liquid at its boiling point
what does viscosity mean?
the ease of the flow of the liquid.
what does volatility mean?
the tendency of a substance to vaporise
usage of liquified petroleum gas?
domestic heating and cooking
what is the equation for the combustion of methane?
methane + oxygen -> carbon dioxide and water
the products of combustion depend on what?
the availability of oxygen
when does complete combustion occur?
when there is a plentiful supply of oxygen
balanced symbol equation for the combustion of methane?
CH4 + 2O2-> CO2 + 2H2O
when does incomplete combustion occur?
when there is an insufficient supply of oxygen
incomplete combustion of carbon containing fuels produces what?
carbon monoxide, soot and water
balanced symbol equation for incomplete combustion?
CH4 + 1.5O2 -> CO + 2H20
carbon monoxide can cause what?
dizziness, loss of consciousness and eventually death
what is sulfur dioxide?
produced by the combustion of fuels containing sulfur
sulfur is oxidised to form what?
sulfur dioxide
sulfur dioxide is dissolved in rainwater to form what?
sulfuric acid and falls as acid rain
acid rain causes what?
the corrosion of limestone
oxides of nitrogen are formed when?
when nitrogen and oxygen react at high temperatures
oxides of nitrogen can cause what?
acid rain and respiratory problems
long chain hydrocarbons are in low or high demand and high or low supply?
low demand and high supply
short chain hydrocarbons are in high or low demand or low or high supply?
high demand and low supply
cracking produces what?
short chain alkanes and alkenes from long chain alkANES
cracking requires temperatures in what range?
600-700 temperature
what catalyst does cracking need?
silica or alumina
definition of cracking?
a thermal decomposition reaction that produces short chain alkanes and alkenes from long chain alkANES
saturated molecules contain what type of bonds?
single bonds only
unsaturated molecules contain what type of bonds between their carbon atoms?
double bonds
alkanes are saturated or unsaturated compounds?
saturated
alkenes are saturated or unsaturated compounds?
unsaturated
cracking is an endo or exothermic reaction?
endothermic
how does catalytic cracking work?
- heating the hydrocarbon molecules to 600-700 to vaporise them
- vapours pass over a hot powdered catalyst of aluminium oxide
-process breaks covalent bonds in the molecules- they come into contact with the surface of the catalyst- causing thermal decomposition
-molecules are broken up in a random way- produces smaller alkanes and alkenes
alkanes are an example of what type of series?
homologous
what are alkENES?
a homologous series who’s functional group is c=c
are alkENES saturated or unsaturated?
unsaturated
what is the general formula for alkENES?
CnH2n
what is the test for alkenes?
bromine water test
in alkENES what will happen to the bromine water?
will become discoloured
in alkANES what happens to the bromine water?
stays orange
