9.5 - Physical properties of organic compounds

Identify the groups of molecules that are arranged in a homologous series.

• methane, ethane, propane, butane

• ethane, ethene, ethyne

• pentane, pentan-1-ol, pentanal, pentanoic acid

• heptan-1-ol, heptan-2-ol, heptan-3-ol, heptan-4-ol

• methanol, ethanol, propan-1-ol, butan-1-ol

What properties are the same or similar within a homologous series?

• Functional group

• Reactivity with other chemicals

• Boiling point

• Carbon chain length

• Solubility in water

Which compound will have the highest boiling point?

• Methane

• Ethane

• Propane

• Butane

Why does butane have a higher boiling point than methane?

• Higher molecular mass leading to slower molecular movement

• Entangling of carbon chains requiring more energy to separate

• Higher dispersion forces to overcome due to more electrons

• More hydrogen bonding to overcome due to more hydrogen atoms

Which compound will have the highest boiling point?

• butan-1-ol

• butanal

• butane

• butanoic acid

Tags

NGSS.HS-PS1-3

Why does butanoic acid have a higher boiling point than butanal?

• Increased carbon chain length

• Higher dispersion forces between molecules

• Hydrogen bonding between molecules

• Faster molecular motion due to streamlined shape

Why does butanoic acid have a higher boiling point than butan-1-ol?

• Dipole-dipole interactions between carbonyl groups

• Hydrogen bonding between carbonyl groups

• Hydrogen bonding between hydroxyl groups

• Hydrogen bonding between carbonyl and hydroxyl groups

Why does butanal have a higher boiling point than butane?

• Dipole-dipole interactions between carbonyl groups

• Hydrogen bonding between carbonyl groups

• Increased dispersion forces due to carbonyl groups

• Butanal and butane have similar boiling points

Identify the compounds that are miscible in water.

• Ethane

• Ethanol

• Ethanal

• Ethanoic acid

• Methyl ethanoate

Identify the compounds that can form hydrogen bonds with identical molecules (i.e. itself, not water).

• Propan-2-ol

• N-methylmethanamine

• N,N-dimethylmethanamine (trimethylamine)

• Ethanal

• Methyl propanoate

Tags

NGSS.HS-PS2-6