Alkanes

Question 1

General formula

Answer 1

CnH2n+2
Saturated hydrocarbon each carbon atom joined to 4 others by single covalent bond (sigma bond)

Question 2

Sigma bond

Answer 2

Each c atom has 4 sigma bonds
Result of overlap of two orbitals, one from each bonding atom
Tetrahedral shape around C atom , 109.5

Question 3

Factors affecting boiling point

Answer 3

Size + shape
Bp increases as CHAIN LENGTH increases
stronger London forces = higher bp

Question 4

Size

Answer 4

As chain length increases , molecules have larger SA, MORE SURFACE CONTACT is possible BETWEEN MOLECULES
- stronger London forces, more energy required to overcome

Question 5

Shape

Answer 5

Branched Alkenes have LOWER bp
Can’t pack closely together , fewer surface points of contact between molecules = induced dipole dipole interactions reduced.

Question 6

Reactivity

Answer 6

Not that reactive
C-C bonds r non- polar
High bond enthalpy for C-C and C-H sigma bonds
Similar EN values of c and h , non polar

Question 7

Combustion

Question 8

Homologous series

Answer 8

Compounds that have the same functional group , with each successive compound differing by CH2
Similar chemical properties