Chapter 12 Flashcards
What are alkanes used for?
fuel
What is the general formula of alkanes?
CₙH₂ₙ₊₂
Are alkanes saturated or unsaturated?
saturated
What is a sigma bond (σ-bond)?
overlap of two orbitals, one from each bonding atom
What is a covalent bond?
shared pair of electrons
How do oil refineries separate crude oil into fractions?
fractional distillation
Why is fractional distillation possible?
boiling points of alkanes are different
Why does boiling point increase as chain length increases?
1) molecules have larger surface area - more surface contact been molecules
2) greater London forces between molecules
3) more energy required to overcome forces
Do branched isomers have lower or higher boiling points?
lower
Why do branched isomers have lower boiling points?
1) fewer surface points of contain between molecules of branched alkanes
2) fewer London forces
3) branches get in the way + prevent molecules getting close together
Why do alkanes lack reactivity?
1) C-H + C-H σ bonds are strong
2) C-C bonds are polar
3) electronegativity of C + H are similar - C-H is considered non-polar
What type of mechanism is the bromination of alkanes?
radical substitution
What stages does the bromination of alkanes take place in?
1) initiation
2) propagation
3) termination
