2. Molecular Representations

In each pair of compounds, which compound has the higher boiling point? Explain your reasoning.

a. octane or 2,2,3-trimethylpentane

List each set of compounds in order of increasing boiling point.

b. Octane, (CH₃)₃C—C(CH₃)₃ and CH₃CH₂C(CH₃)₂CH₂CH₂CH₃

Choose the molecule in each pair you'd expect to have the higher boiling point. Explain your reasoning.

(b)

Ionic compounds like sodium acetate have a high melting point. Despite this, they are highly soluble in water. Why?

Despite methylcyclohexane (98.2 amu) having a higher molecular weight than toluene (92.1 amu), toluene melts at a higher temperature. Why? [Think about how the molecules can interact with each other based on their shape.]

Choose the molecule in each pair you'd expect to have the higher boiling point. Explain your reasoning.

(a) eicosane ( C₂₀H₄₂) vs pentadecane

Draw a picture of the hydrogen bonding in methanol.

Which has

g. the higher boiling point: 1-bromopentane or 1-chloropentane?

Which has

h. the higher boiling point: diethyl ether or butyl alcohol?

For each pair of compounds, predict which compound has the higher boiling point. Check [TABLE 6-2] to see if your prediction was right; then explain why that compound has the higher boiling point.

c. 1-bromobutane and 1-chlorobutane

For each pair of compounds, predict which compound has the higher boiling point. Check [TABLE 6-2] to see if your prediction was right; then explain why that compound has the higher boiling point.

b. isopropyl chloride and tert-butyl bromide

For each pair of compounds, predict which compound has the higher boiling point. Check [TABLE 6-2] to see if your prediction was right; then explain why that compound has the higher boiling point.

a. isopropyl bromide and n-butyl bromide

For each pair of compounds, predict which one has the higher molecular dipole moment, and explain your reasoning.

c. cis-2,3-dibromobut-2-ene or trans-2,3-dibromobut-2-ene

d. cis-1,2-dichlorocyclobutane or trans-1,3-dichlorocyclobutane

For each pair of compounds, predict the one with a higher boiling point. Which compounds have zero dipole moments?

b. cis- or trans-2,3-dichlorobut-2-ene

For each pair of compounds, predict the one with a higher boiling point. Which compounds have zero dipole moments?

c. cyclohexene or 1,2-dichlorocyclohexene