DF - Alkanes Flashcards
Explain why the straight chain isomer has a higher boiling point than any of its branched chain structural isomers
Branched chains have less surfaced area
Branched chains have less Van Der Waal’s forces
Explain why the straight chain isomer is converted by the petroleum industry into its branched chain isomers
Branched chain isomers have more efficient combustion
Suggest, with the aid of an equation, how NO is formed within an aeroplane engine
N2 + O2 -> 2NO
Name one other bromine-containing organic product which is formed when methane reacts with bromine
Dibromomethane
State and explain the trend in boiling points of alkenes
Boiling point increases with chain length
Due to more intermolecular forces
Formation of cyclic alkanes equation
Alkane -> cyclic alkane + H2
What is meant by the term fractional distillation
Separation by difference in boiling point
Explain why 2-methylhexane and 2,3-dimethylpentane have different boiling points
If branched, less points of contact
Less intermolecular bonds
Describe, with the aid of a diagram, the formation of a pi bond
Describe, with the aid of a suitable example, why some alkenes show cis-trans isomerism
- cis & trans diagram
a double bond restricts rotation
Each C in the C=C double bond is bonded to two different atoms or groups
State the type of reaction
Free radical substitution
Outline the process of processing the fractions from crude oil
- High temps or a catalyst is required
- Cracking occurs
- Formation of cyclic structure
State clearly the industrial importance of the products formed in isomerisation
- USed in fuels
- More efficient fuels
- H2 used in Haber process
Draw compound A
State a suitable reagent for dehydrating alcohol
H2SO4
Write a balanced equation for the dehydration of cyclohexanol
Explain why the isomer with the most branches has the lowest boiling point
The more branches, the less energy required to break the bonds
As branched alkanes have less Van Der Waal’s forces
Suggest one reason why oil companies reform alkanes
Better fuels
How to calculate the percentage by mass of oxygen in a compound
(Mr of oxygen / total Mr) x100
State what happens to the free radicals in the termination steps
React with each other
EXplain why, in the long term, ethanol could replace oil-based fuels
Oil is non-renewable
Ethanol is renewable from plants
Equation for ethene being converted into ethanol
C2H4 + H2O -> C2H5OH
What conditions are needed for ethene to be converted into ethanol?
Phosphoric acid catalyst
Steam
1 degree higher
As 1 less branch
State why branched chain alkanes and cycloalkanes are more useful than straight chain alkanes
More efficient
More volatile
