NESA Chemistry Hydrocarbons

Incorrect. Liquid hydrocarbons are typically toxic, flammable, and insoluble in water, meaning pouring them down the sink can contaminate water supplies and create plumbing fire hazards.

Incorrect. Disposing of flammable liquids in a standard garbage bin poses a severe fire risk and allows toxic fumes to evaporate into the surrounding air.

Incorrect. Igniting hydrocarbons in an uncontrolled manner is extremely dangerous, risking uncontrolled fires, explosions, and the release of toxic combustion byproducts.

Correct. Hazardous chemicals like liquid hydrocarbons must be collected in designated, properly labeled chemical waste containers to ensure safe handling and regulated disposal by professionals.

This is the correct order. Heptane has only weak London dispersion forces, heptan-2-one has dipole-dipole interactions, heptan-1-ol forms hydrogen bonds, and heptanoic acid forms strong hydrogen-bonded dimers, resulting in progressively higher boiling points.

This order is incorrect because heptan-1-ol has a higher boiling point than heptan-2-one. The hydrogen bonding in the alcohol is stronger than the dipole-dipole interactions in the ketone.

This incorrectly lists the compounds in decreasing order of boiling point, starting with the strongest intermolecular forces (heptanoic acid) and ending with the weakest (heptane).

This incorrectly lists the compounds in decreasing order of boiling point and mistakenly suggests that heptan-2-one has a higher boiling point than heptan-1-ol.

Intramolecular forces hold atoms together within a molecule; boiling involves separating molecules from one another, not breaking bonds within them. Furthermore, alkanes do not contain the electronegative atoms necessary for hydrogen bonding.

Alkanes are nonpolar hydrocarbons that lack the hydrogen atoms bonded to highly electronegative atoms (N, O, F) required to form hydrogen bonds.

Dispersion forces are intermolecular (between molecules), not intramolecular. Intramolecular forces refer to the covalent bonds holding the carbon and hydrogen atoms together.

Boiling requires overcoming intermolecular forces. As the carbon chain length increases, the molecule's surface area and electron count increase, leading to stronger London dispersion forces that require more energy to overcome.

Butanone ($C_4H_8O$) has a longer carbon chain than propanone, leading to stronger London dispersion forces and a higher boiling point.

Hexanone ($C_6H_{12}O$) has the highest molecular weight and longest carbon chain among the options, resulting in the strongest intermolecular forces and the highest boiling point.

Pentanone ($C_5H_{10}O$) has a larger molecular size than propanone, which results in stronger intermolecular attractions and a higher boiling point.

Propanone ($C_3H_6O$) has the shortest carbon chain and lowest molecular mass, resulting in the weakest London dispersion forces and therefore the lowest boiling point.