Application organic chemistry

Functional group and disinfectant mechanism of rubbing alcohol

Contains a hydroxyl group ($-\text{OH}$); acts as a disinfectant by disrupting microbial cell membranes and denaturing proteins.

Structural feature and role of ethylene glycol in coolant mixtures

A diol containing two hydroxyl groups ($-\text{OH}$); lowers water's freezing point and raises its boiling point to prevent freezing and overheating.

Chemical basis and structural properties of polyethylene in plastic bottles

Synthesized from alkenes such as ethene; long covalently bonded polymer chains yield strong, durable, lightweight, and easily mouldable material.

Functional group and solvent properties of acetone in nail polish remover

Acetone is a small molecule that can interfere w nail polish particles, it is a versatile solvent that dissolves nail polish because its polar carbonyl group and nonpolar carbon groups allow it to interact with different substances.

A ketone containing a carbonyl group ($\text{C=O}$); functions as a polar solvent that dissolves polish resins and evaporates quickly due to high volatility.

Functional group and sensory characteristics of ethyl ethanoate

An ester ($-\text{COO}-$); exhibits a pleasant, fruity scent and high volatility, making it suitable for perfumes and artificial flavourings.

Evaporation rate comparison: water vs. acetone

Water evaporates more slowly because strong hydrogen bonding requires significant energy to separate molecules, whereas acetone relies on weaker dipole–dipole and dispersion forces.

Evaporation rate comparison: ethanol vs. hexane

Ethanol evaporates more slowly because its combined hydrogen bonding, dipole–dipole, and dispersion forces are stronger than the London dispersion forces of hexane alone.

Intermolecular mechanism causing water to form beads on wax

Strong cohesive hydrogen bonds among water molecules exceed the weak adhesive attractions to nonpolar wax, causing droplets to bead.

Intermolecular mechanism causing water to bead on Teflon cookware

Teflon is nonpolar and forms very weak attractions with polar water; strong water–water hydrogen bonds keep water cohesive rather than spreading.

Physical mechanism enabling propane gas to be stored as a liquid

Propane molecules have weak London dispersion forces; applied pressure forces molecules close enough together to condense the gas into a liquid at room temperature.

Boiling point comparison: butane vs. octane

Octane has a higher boiling point because its larger molecular size contains more electrons, resulting in stronger London dispersion forces that require more thermal energy to overcome.

Dual chemical properties that make ethanol an effective perfume solvent

Contains a polar $-\text{OH}$ group to hydrogen-bond alongside a nonpolar hydrocarbon region to dissolve aromatic compounds, while its volatility helps release scents.

Structural basis for the moisturizing effect of glycerol

Contains three hydroxyl groups ($-\text{OH}$) that form extensive hydrogen bonds with water molecules, attracting and retaining moisture in the skin.

Solubility principle explaining why hexane dissolves nonpolar grease

'Like dissolves like': nonpolar hexane forms compatible dispersion attractions with nonpolar grease, whereas polar water cannot establish favorable attractions with grease.

Why ethylene glycol is preferred over ethanol as an engine coolant

Features two $-\text{OH}$ groups that engage in strong hydrogen bonding with water, effectively depressing the freezing point and raising the boiling point while remaining less volatile.

Boiling point comparison: methane vs. methanol

Methanol has a significantly higher boiling point because its $-\text{OH}$ group allows hydrogen bonding and dipole–dipole attractions, whereas nonpolar methane has only weak London dispersion forces.

Chemical advantage of combining water and organic solvents in cleaning products

Polar water dissolves polar and ionic grime, while organic solvents dissolve nonpolar oils and grease, enabling the removal of a broader range of soils than water alone.