Alkenes Flashcards
How many bonded pairs do double bonds contain?
2
Define the term ‘electrophile’?
Electron pair acceptor
Which two bonds are present in a double carbon-carbon bond?
Pi bond
Sigma bond
Which bond breaks in electrophillic addition? Why
Pi bond because it is more exposed than the sigma bond and therefore more easily accessible
Why must an electrophile contain a positive region?
To attract the negative electron rich centre as opposites attract
What is an addition reaction?
A reaction whereby two molecules join to make a larger molecule
How do we identify which part is slightly negative and which is slightly positive in an electrophile which consists of two elements?
The most electronegative atom carries the slightly negative charge and thus, the other atom has the positive charge
What does a curly arrow represent?
Movement of electrons
What type of product is formed in hydrogenation (Alkenes with hydrogen)?
Alkanes
What are the conditions required for hydrogenation?
Nickel catalyst
150C
What type of product is produced in halogenation (addition of a group 7 element to an Alkene)?
Haloalkane
What test is carried out when testing for an Alkene?
Addition of bromine water to solution
What is observed when bromine water is added to an Alkene?
Colour change of orange to colourless
Which type of bonds are unsaturated?
Double bonds
Which type of bonds are saturated?
Single bonds
What is the hydration of ethene?
Addition of steam to ethene to produce an alcohol
What does the reaction of an alkene and steam produce?
An alcohol
What are the conditions for the hydration of an alkene?
Steam and gaseous alkene
High temperature (300C)
High pressure
Conc phosphoric acid catalyst
When there is a combination of possible products due to an unsymmetrical alkene, how do we decide which is the major product?
Choose the product with the most stable carbocation (eg tertiary is more stable than secondary and secondary is more stable than primary; choose the most stable)
What is addition polymerisation
When an alkene becomes saturated under specific conditions to form long chain polymers
What is a monomer
A small molecule
What is a polymer
A long chain molecule containing many monomers
Give the conditions required for addition polymerisation
High temperature
High pressure
Catalyst
How do you name a polymer made from a monomer
Same with poly in front of it
How are repeat units displayed in addition polymerisation
Monomer inside brackets
What are the conditions for hydration of ethene?
Catalyst H3PO4
Steam
State two ways ethanol can be manufactured on a large scale
Fermentation
Hydration of ethene
Out of fermentation and hydration of ethene in the production of ethanol, which is more sustainable?
Hydration of ethene has a higher atom economy
Fermentation does not require high temperatures and pressures so lower energy required
Ethene is created from crude oil which is non-renewable and is finite
So overall, fermentation is more sustainable
How is atom economy calculated
Total of desired products / total of all products x100
