Solutions, Solubility, and Intermolecular Forces – Lecture Review

Fill-in-the-blank flashcards covering electrostatic bonding, intermolecular forces (dispersion, dipole–dipole, hydrogen bonding), polarizability, boiling-point trends, solubility concepts (solute, solvent, miscibility), hydration spheres, precipitation, and the ‘like dissolves like’ rule.

All chemical bonding, whether ionic or covalent, falls under the umbrella of __ interactions.

electrostatic

The weak attractive forces between separate covalent molecules are known as __ forces (also called Van der Waals forces).

intermolecular

The three main types of intermolecular forces are __, __, and __.

dispersion forces; dipole–dipole forces; hydrogen bonding

Dispersion forces are sometimes called or dipoles because they exist only momentarily.

temporary; instantaneous induced

__ is the ease with which a molecule’s electron cloud can be distorted to form an induced dipole.

Polarizability

The larger the number of __ a molecule has, the stronger its dispersion forces.

electrons

Among the halogens, the boiling point trend F₂ < Cl₂ < Br₂ < I₂ is explained by increasing __ forces.

dispersion

Between pentane (C₅H₁₂) and decane (C₁₀H₂₂), the higher boiling point of decane is due to greater __ forces from its larger electron cloud.

dispersion

Dipole–dipole forces occur only in molecules and are (temporary/permanent).

polar; permanent

HCl has a much higher boiling point than F₂ of similar size because HCl experiences both dispersion and – forces.

dipole–dipole

Hydrogen bonding is a particularly strong form of dipole–dipole interaction that requires H directly bonded to __, __, or __.

nitrogen; oxygen; fluorine

A water molecule can hydrogen-bond to another water molecule when the lone pair on one O atom attracts the almost bare __ of a neighboring H.

proton (hydrogen nucleus)

Hydrogen bonding is responsible for the unusually high boiling point of __, NH₃, and HF.

H₂O (water)

Complementary base pairing in DNA (A–T and G–C) is stabilized primarily by __ bonding.

hydrogen

In a solution, the substance being dissolved is the __, while the substance doing the dissolving is the __.

solute; solvent

A transparent, single-phase mixture of solute and solvent is called a __.

solution

If two liquids mix to form one layer they are described as __; if they form two layers they are __.

miscible; immiscible

For a solute to dissolve, the solute–solvent attractions must be __ (weaker/equal/stronger) than or equal to the solute–solute and solvent–solvent attractions.

equal to or stronger

When NaCl dissolves in water, water molecules arrange so that the O atom faces Na⁺ and the H atoms face Cl⁻, forming __ of hydration.

spheres

Sugar dissolves in water because both are __; the sugar molecules remain intact rather than ionizing.

polar

I₂ does not dissolve in water because water–water attractions exceed water–I₂ attractions; instead I₂ is soluble in __ solvents like cyclohexane.

non-polar

The rule of thumb for solubility is “ dissolves .”

like; like

An insoluble solid that forms when two solutions are mixed is called a __, and the process is __.

precipitate; precipitation

In the ionic equation Ag⁺ + Cl⁻ → AgCl(s), AgCl is identified as the __ because it is insoluble in water.

precipitate

Hydrocarbons are generally __ (polar/non-polar) and therefore are immiscible with water.

non-polar

Non-polar liquids that do not dissolve in water usually __ (sink/float) because they are less dense than water.

float

Dispersion forces are present in __ molecular substances.

all

Dipole–dipole forces plus dispersion forces give polar molecules __ (higher/lower) boiling points than non-polar molecules of similar size.

higher

Hydrogen bonding involves attraction between a highly electronegative atom’s lone pair and an almost bare __ on an adjacent molecule.

hydrogen nucleus (proton)

The cloudy, pulpy material seen in unfiltered orange juice is an everyday example of a __ in suspension.

precipitate (insoluble solid)

Because of hydrogen bonding, water, ammonia, and hydrogen fluoride have melting and boiling points that are __ (higher/lower) than expected for their molar masses.

higher

Cyclohexane molecules are no more strongly attracted to each other than to I₂, so iodine can __ (dissolve/precipitate) in cyclohexane.

dissolve