Alkanes And Hydrocarbons Flashcards
Alkanes undergo what type of reaction mechanism?
Radical substitution
What are the 3 stages to the reaction mechanism?
Initiation
Cl-Cl -UV-> Cl• + Cl•
Propagation
CH4 + Cl• -> •CH3 + HCl
•CH3 + Cl2 -> CH3Cl + Cl•
Termination
Cl• + Cl• -> Cl2
What conditions and bond fission does this reaction mechanism require?
UV radiation and homolytic fission
What is homolytic fission?
Homolytic fission is the breaking of a covalent bond, with one bonded electrons going to each atom, forming 2 radicals (X-Y —> X• + Y•
What is an alkane?
An alkane contains C-C single bonds only
What are the 2 factors that affect the boiling points of alkanes?
Chain length
Longer chains -> higher BP
as there is an increase in surface area hence, stronger van der Waals forces/more points of contact
Branching
Branch-chain alkanes -> lower BP
because chains cannot pack closely together, fewer points of contact between molecules so van der Waals forces are weaker
What are radicals?
A species with a unpaired electron
The combustion of alkanes and it’s products
The combustion of alkanes is burning in a plentiful supply of oxygen to form CO2 and H2O
Incomplete combustion and it’s products
Incomplete combustion is burning in a limited supply of oxygen to form carbon monoxide, CO
What are the features and side-effects of carbon monoxide?
Poisonous
Colourless
Odourless
Has toxic effects -> harmful/fatal
What is fractional distillation?
Fractional distillation is the separation of the components in a liquid mixture into fractions which differ in BP by means of distillation, typically using a fractional column
What is meant by the term aliphatic?
When carbon atoms are joined together in straight or branched chains
What is meant by the term alicyclic?
When carbon atoms are joined together in a ring structure
What is a hydrocarbon?
A hydrocarbon is a compound of carbon and hydrogen only
What is a saturated hydrocarbon?
Saturated hydrocarbons have single bonds only
