Chapter 12 Flashcards
What are Alkanes?
They are the main components of natural gas and crude oil. They are mainly used as fuels.
What is the general formula of Alkanes?
C2nH2n+2
What type of bonds do Alkanes have?
Sigma bonds
How does a sigma bond form?
Overlap of orbitals
Shape and bond angle of alkanes
109.5°
Tetrahedral
Factors affecting the boiling point of Alkanes
Chain length:
If the length increases, there are more electrons so there are stronger dipoles, the strength of London forces increase
Have a larger surface area so more surface contact is guaranteed, also making London force stronger
Branching:
More branches mean less surface area of contact so weaker London forces.
Shape means its harder for the alkane molecules to pack together, weakening intermolecular forces even further
Why are alkanes generally unreactive?
C-C and C-H sigma bonds are strong
C-C bonds are non polar
C-H bonds are considered non polar due to similar Electronegativity
What does the complete combustion of alkanes produce?
Water and carbon dioxide
What does the incomplete combustion of alkanes produce?
Water
Carbon monoxide or soot
What is needed for alkanes to react with halogens?
High energy uv radiation
Sunlight is an example
What type of reaction occurs between halogens and alkanes?
Substitution reaction
What are the 3 steps that occur during the reaction mechanism?
Initiation
Propagation
Termination
What happens during initiation?
2 highly reactive halogen radicals are formed
What happens during propagation?
A chain reaction occurs. Process will continue to happen until termination occurs or all the reactants has been used up. The former is the more likely to happen.
What happens during termination?
Occurs when 2 radicals collide. Radicals are removed and a molecule forms, stopping the reaction
