Question

1)Which compound below would be expected to have the highest boiling point?

a) CH3-CH2-CH2-CH2-CH2-CH2-CH3

b) CH3-CH2-CH2-CH2-CH-CH3
|
CH3

c) CH3-CH-CH2-CH-CH3
| |
CH3 CH3


d) CH3
|
CH3-CH-C-CH3
| |
CH3 CH3

Do I use molar mass to determine which is the highest?

Answer 1

You can do the molar mass but won't the molar mass be the same for all of them. They look like 7 carbons to me and if they are saturated I expect all of the molar mass will be the same.
The straight chain one will be the highest b.p. Branching the chain makes the b.p. lower. The more branched the lower the b.p.

Answer 2

Why is it that the straight chain is higher?

Answer 3

Branching decreases the surface area some but the explanation I've always heard is that the "long" chains get intertwined and interfere with "escaping" from the liquid.

Answer 4

ok thank you!!