Chapter 12 Alkanes

Question 1

What are alkanes?

Answer 1

Saturated hydrocarbons, containing only carbon and hydrogen atoms joined together by single covalent (sigma bonds)
Main components of natural gas and crude oil, most stable organic compound

Question 2

What is a sigma bond?

Answer 2

Result of the overlap of 2 orbitals, positioned on a line directly between bonding atoms
Strong and non-polar

Question 3

How is crude oil separated?

Answer 3

Fractional distillation.
Increasing chain length of alkanes increase the boiling point
London forces increase with the chain length, so more energy is required to overcome forces

Question 4

What affect does branched isomoers have?

Answer 4

Lower boiling points
Less surface points of contact in between molecules of branched alkanes, giving less London forces
Branches get in the way and prevent branched molecules getting close

Question 5

How does substitution reaction take place?

Answer 5

In presence of sunlight, alkanes react with halogens to form substitution reaction
Initiation stage: covalent bond is broken by homolytic fission to form highly reactive radicals, energy is provided from UV radiation
Propagation will continue until all reactants have been used up
Termination stage: 2 radicals collide, forming a molecule with all electrons paired