Alkanes Flashcards
(13 cards)
What is the general formula of alkanes ?
CnH2n+2
What are constitutional isomers ?
Structural isomers
They have the same molecular formula, but the atoms are connected in different ways.
There are 3 types: chain, position and functional group isomers
What are conformational isomers ?
Same molecular formula, but different spatial arrangements of atoms in a molecule that result from rotation around single sigma bonds
What is a primary carbon ?
A carbon that is bonded to ONE other carbon
What is a radical ?
An unpaired electron
Why is tertiary radial more stable than a primary and secondary radical ?
Due to hyperconjugation
What is hyperconjugation ?
It is when electrons in a sigma bond (usually C-H or C-C) delocalise into an adjacent empty or partially filled orbital (such as an empty p orbital).
This delocalisation spreads out electron density, increasing stability.
What does complete combustion produce ?
H20 and CO2
What does incomplete combustion produce ?
CO and/or C
What is cracking ?
Breaking large alkanes into smaller alkanes and alkenes.
Short chain molecules are more useful than longer chains.
What is a dehydrogenation reaction of alkanes ?
Removal of H2 to produce an unsaturated hydrocarbon (alkene)
What is a halogenation reaction in alkanes ?
Replacing hydrogen with a halogen
During the reaction of primary, secondary, and tertiary alkanes:
Why does the observed product ratio reverse when the temperature is increased?
The reaction has enough energy to overcome higher activation barriers.
The system now favors the formation of more stable radicals (secondary or tertiary)
