chapter 12 alkanes Flashcards
are alkanes saturated or unsaturated hydrocarbons?
saturated
what is an alkane?
a saturated hydrocarbon containing single carbon-carbon bonds
what is the general formula of an alkane?
CnH2n+2
are alkane bonds polar? why/why not?
non-polar, because carbon and hydrogen have similar electronegativities
what is the shape and angle of an alkane?
tetrahedral, 109.5°
what is a covalent bond?
a shared pair of electrons
what happens to the boiling point as alkane chain length increases? why?
- boiling point increases
- increased chain length, greater surface area of contact
- stronger london forces, more energy required to overcome these forces
what happens to the boiling point of an alkane as branching increases? why?
- boiling point decreases
- more branching, less surface area of contact
- weaker london forces, less energy required to overcome these forces
are alkanes soluble in water?
insoluble, because hydrogen bonds in water are stronger than the london forces in alkanes
how reactive are alkanes?
very unreactive
what reactions will alkanes undergo?
combustion and halogenation
what type of reaction is combustion?
oxidation reaction
what is complete combustion?
combustion that occurs with plentiful supply of oxygen
what are the products of the complete combustion of alkanes?
carbon dioxide and water
what are the three stages of free radical substitution?
- initiation: breaking halogen bond to form free radicals
- propagation: chain part of the reaction where products are formed but free radical remains
- termination: free radicals removed, stable products formed
