Alkanes

Question 1

What is the general formula for Alkanes?

Answer 1

Cn H2n+2

Question 2

Whats the shape and bonding of Alkanes?

Answer 2

4 bonding pair regions , 0 lone pair regions so Tetrahedral 109.5 degrees

Question 3

Are the molecules polar or non polar?

Answer 3

The difference in electronegativity is slight

Question 4

What are the forces between the molecules?

Answer 4

Induced Dipole - Dipole intermolecular forces between the molecules

These get stronger as the molecules get longer due to increased points of contact between the molecules.

Therefore more energy is needed to overcome the forces

Question 5

Whats the correlation between unbranched alkanes and melting points?

Answer 5

Unbranched Alkanes have the highest melting points they have the most points of contact / highest ability for packing closely together so have the strongest induced dipole dipole intermolecular forces which require more energy to overcome.

Question 6

Whats the correlation between branched alkanes and melting points

Answer 6

These have lower melting points as they have the least points of contact so low ability of close packing resulting in weak intermolecular forces so less energy required.