Organic Chemistry 1 Flashcards
How can we separate petroleum into useful fractions?
fractional distillation
How do the boiling points of fractions change as you go down the fractionating column?
as you go down, the boiling points increase
How does the viscosity of fractions change as you go down the fractionating column?
as you go down, the viscosity increases
How do the volatilities of fractions change as you go down the fractionating column?
as you go down, the volatility decreases
How do the chain lengths of fractions change as you go down the fractionating column?
as you go down, chain length increases
Name the three fossil fuels.
coal, natural gas and petroleum
What is the main constituent of natural gas?
methane
Define the term ‘hydrocarbon’.
Compounds containing hydrogen and carbon only
What process is used to separate petroleum into its fractions?
Fractional distillation
What is petroleum?
a mixture of hydrocarbons
What is a fraction?
a group of hydrocarbons with similar chain lengths
What are features of fractions obtained from petroleum at the top of the fractionating column?
- lower boiling points
- runny
- volatile
- smaller chain length
What are features of fractions obtained from petroleum at the bottom of the fractionating column?
- higher boiling points
- viscous
- low volatility
- bigger chain length
What is the order of the fractions, from the smallest chain to the largest?
refinery gas
gasoline
naphtha
paraffin
diesel oil
fuel oil
lubricating fraction
bitumen
What is the use of refinery gas?
heating and cooking
What is the use of gasoline?
fuel in cars
What is the use of naphtha?
chemical feedstock
What is the use of paraffin?
jet fuel
What is the use of diesel oil?
fuel used in diesel engines
What is the use of fuel oil?
fuel in ships and home heating systems
What is the use of lubricating oil?
for lubricants, waxes and polishes
What is the use of bitumen?
making roads
What is the general formula of alkanes?
CnH2n+2
What is the general formula of alkenes?
CnH2n
What is a functional group?
an atom or a group of atoms that determine the chemical properties of a homologous series
What is a structural formula?
an unambiguous description of the way atoms in a molecule are arranged
What are structural isomers?
compounds with the same molecular formula, but different structural formulae
What is a homologous series?
a family of similar compounds with similar chemical properties due to the presence of the same functional group
What is a saturated compound?
contains molecules containing only C-C single bonds
What is an unsaturated compound?
contains molecules containing at least one C-C double + bond
What are the general characteristics of a homologous series?
- have the same functional group
- have the same general formula
- trend in physical properties
- similar chemical properties
How is the bonding in alkanes?
single covalent
saturated hydrocarbons
Are alkanes reactive or unreactive?
generally unreactive, except in combustion and with halogens in UV light
What happens in a substitution reaction?
one atom/group of atoms is replaced by another atom/group of atoms
What type of reaction is the reaction between alkanes and chlorine?
substitution + photochemical
What is the condition necessary for alkanes to react with chlorine? Why?
UV light, it gives the activation energy
How is the bonding in alkenes?
contains a covalent carbon-carbon double bond
unsaturated hydrocarbons
Why is cracking used?
-because long chain alkanes can be turned into more useful short chain alkanes (can be used for fuels)
-alkenes produced can be used to make polymers (plastic)
What happens when an alkene comes into contact with aqueous bromine? How does this differ from an alkane’s reaction with aqueous bromine?
alkene - decolorises aqueous bromine
alkane - no difference
How many products are formed in an addition reaction?
ONLY one
What type of reaction do alkenes undergo?
addition
What happens in a reaction between an alkene and hydrogen?
the product becomes an alkane, with the same number of carbon atoms than before but different number of hydrogen atoms
What is necessary for an alkene to react with hydrogen?
nickel + 200ºC
What happens when an alkene reacts with steam?
it forms an alcohol
What is necessary for an alkene to react with steam?
300ºC + phosphoric acid
What conditions are necessary for cracking?
high temperature
catalyst - either ceramic or aluminium oxide
What is produced in cracking?
shorter chain alkanes and alkenes (more useful)
What type of reactions do alkanes undergo?
substitution reactions
State in order the prefixes of alkanes and alkenes according to the number of carbon atoms.
- meth-
- eth-
- prop-
- but-
- pent-
- hex-
- hept-
- oct-
Which hydrocarbons are more volatile? At the top or bottom of the fractionating column?
more volatile if higher up the fractionating column
the smaller the molecule, the more volatile
Which hydrocarbons are more viscous? At the top or bottom of the fractionating column?
the larger the molecule, the more viscous
word equation for combustion
fuel (hydrocarbon) + oxygen -> carbon dioxide + water
word equation for combustion
fuel (hydrocarbon) + oxygen -> carbon dioxide + water
what is combustion
burning
when does incomplete combustion occur?
when there is a shortage of oxygen
what is formed as result of incomplete combustion? Why is it dangerous?
carbon monoxide (colorless odorless gas) and/ or soot. carbon monoxide is dangerous as it binds irreversebly to haemoglobin, reducing its ability to carry oxygen
what are the possibilities of products in cracking
- alkene + hydrogen
- alkene + alkane
- alkane + alkene + alkane
word equation for incomplete combustion
fuel + oxygen -> carbon monoxide + water
process of fractional distillation (so para annuca - mari ignora esse card)
- The boiling crude oil is transferred into a large fractioning column- The lighter gaseous hydrocarbon rises the column- When gaseous hydrocarbon rises the column, it starts to cool, and when the temperature reaches below boiling points, it is converted to a liquid state.
