Question

The boiling points for a set of compounds in a homologous series can be qualitatively predicted using intermolecular force strengths. Using their condensed structural formulas, rank the homologous series for a set of alkanes by their boiling point.

Rank from highest to lowest boiling point. To rank items as equivalent, overlap them.

a)CH3CH2CH2CH3
b) CH3CH2CH2CH2CH2CH3CH3
c) CH3CH2CCH2CH3CH3
d)CH3CH2CH2CH2CH2CH2CH3

Answer 1

Answer:

Descending order of boiling point: (d)  > (c) > (b) > (a)

Explanation:

The given compounds are:

a) CH₃CH₂CH₂CH₃ – butane (4 carbon Straight-change)

b) CH₃CH₂CH₂CH₂CH₂CH₃ – hexane (6 carbon Straight-change)

c) CH₃CH₂C(CH₃)₂CH₂CH₃ – 3,3-dimethylpentane (7 carbon Branched chain)

d)CH₃CH₂CH₂CH₂CH₂CH₂CH₃ – heptane (7 carbon Straight-change)

Boiling point is defined as the temperature at which the substance changes from the liquid to the vapor state. It is generally dependent upon the molecular mass, branching and the intermolecular forces.

Since all the given compounds are alkanes. Thus, they all exhibit weak intermolecular van der Waals forces.

Therefore, the boiling point of alkanes depends only on the molecular mass or the number of carbon atoms and the branching.

The boiling point of a molecule increases with molecular mass or the number of carbons and decreases with branching.

Therefore, the descending order of boiling point of alkanes is:

(d) CH₃CH₂CH₂CH₂CH₂CH₂CH₃ (heptane, 7 carbon Straight-change) >

(c) CH₃CH₂C(CH₃)₂CH₂CH₃(3,3-dimethylpentane, 7 carbon Branched-chain) >

(b) CH₃CH₂CH₂CH₂CH₂CH₃ (hexane, 6 carbon Straight-change) >

(a) CH₃CH₂CH₂CH₃ (butane, 4 carbon Straight-change)

Answer 2

The decreasing order for boiling point will be : d > c > b > a.

The boiling point can be described as the temperature that has been responsible for the conversion of liquid state to vapor state. The boiling point has been dependent on the molar mass and branching. Since all are alkanes, the force has been the same.

The decreasing order for boiling point will be :

d > c > b > a

• Heptane being the straight hydrocarbon has the highest boiling point.

• 3,3-dimethylpentane has been 7 carbon chained branched hydrocarbon, thus the boiling point increased.

• hexane is a straight hydrocarbon but has a low molecular weight. so the boiling point has been increased further.

• Butane has 4 carbon straight chains, thus having the lowest boiling point.

For more information about the boiling point, refer to the link:

https://brainly.com/question/2153588