Chapter 12 - Alkanes

Question 1

What is the general formula of alkanes?

Answer 1

CnH2n+2

Question 2

What kind of bonds are formed in alkanes?

Answer 2

Sigma bonds

Question 3

What is a sigma bond?

Answer 3

Normal covalent bond - it’s the overlap of 2 orbitals

Question 4

How are alkanes separated?

Answer 4

By different boiling points in fractional distillation

Question 5

How does chain length affect boiling point?

Answer 5

Longer chains increase boiling point because there is greater surface area of contact between molecules so there are stronger London forces.

Question 6

What is the effect of branching on boiling point?

Answer 6

Lowers boiling point because there is less surface area of contact between molecules so there are weaker London forces.

Question 7

Why are alkanes not very reactive?

Answer 7

C-C and C-H sigma bonds are strong.
C-C bond is non-polar.
C and H have very similar electronegativity so C-H is also non-polar.