CH 10 Liquids and Solids Lecture Notes

Flashcards for reviewing General Chemistry II lecture notes, focusing on the topics of liquids, solids, intermolecular forces, and chemical kinetics.

What determines the phase in which a substance exists?

The relative extents of intermolecular forces and the kinetic energy of its molecules.

What are intramolecular forces?

Forces within the molecule that keep the molecule together, for example, the bonds between the atoms.

What are intermolecular forces?

The attractions between molecules, which determine many of the physical properties of a substance.

What are dispersion forces?

Attractive forces caused by temporary dipoles due to fluctuations in the electron distribution in atoms and molecules (also known as London dispersion forces).

What are dipole-dipole attractions?

Attractive forces between polar molecules due to their structure.

What is a hydrogen bond?

An especially strong dipole–dipole attraction that results when H is attached to an electronegative N, O, or F atom

How does molar mass affect polarizability?

Higher molar mass = more electrons = larger electron cloud = increased polarizability = stronger attractions

How does the shape of a molecule affect intermolecular attraction?

Greater surface-to-surface contact = larger induced dipole = stronger attraction

What properties do polar molecules has that nonpolar molecules often lack?

Polar molecule have a permanent dipole.

How does polarity influence boiling and melting points?

The permanent dipole adds to the attractive forces between the molecules, raising the boiling and melting points relative to nonpolar molecules of similar size and shape.

List the types of intermolecular forces from weakest to strongest.

Dispersion forces < Dipole-dipole forces < Hydrogen bonding < Ion-dipole force

What is viscosity?

The resistance of a liquid to flow.

How do intermolecular forces affect viscosity?

The stronger the intermolecular attractive forces, the higher the liquid’s viscosity will be.

How does molecular shape affect viscosity?

The more spherical the molecular shape, the less the viscosity will be.

How does increasing the temperature of a liquid affect its viscosity?

Raising the temperature of a liquid decreases its viscosity.

What is surface tension?

The energy required to increase the surface area of a liquid, or the force required to increase the length of a liquid surface by a given amount.

How do intermolecular forces affect surface tension?

The stronger the intermolecular attractive forces, the higher the surface tension will be.

How does raising the temperature of a liquid affect its surface tension?

Raising the temperature of a liquid decreases its surface tension.

What is cohesive force?

The IMFs between identical molecules of a substance.

What is adhesive force?

The IMFs between two different molecules.

What is capillary action?

When a liquid flows within a porous material due to the attraction of the liquid molecules to the surface of the material and to other liquid molecules.

What determines the curving of the liquid surface in a thin tube (meniscus)?

The competition between intermolecular adhesive and cohesive forces.

The meniscus of water is concave in a glass tube because…

its adhesion to the glass is stronger than its cohesion for itself.

The meniscus of mercury is convex in a glass tube because…

its cohesion for itself is stronger than its adhesion for the glass.

What is vaporization?

The change from the liquid phase to the gas phase.

What is condensation?

The change from the gas phase to the liquid phase.

Define dynamic equilibrium.

When two opposite processes reach the same rate so that there is no gain or loss of material.

How do intermolecular attractions affect equilibrium vapor pressures?

Different substances will exhibit different equilibrium vapor pressures.

Liquids that evaporate easily are considered…

Volatile.

Liquids that do not evaporate easily are considered…

Nonvolatile.

What is vapor pressure?

The pressure exerted by the vapor when it is in dynamic equilibrium with its liquid.

How does increasing temperature affect vapor pressure?

Increasing the temperature increases the vapor pressure.

What is the boiling point of a liquid?

The temperature at which its equilibrium vapor pressure is equal to the pressure exerted on the liquid by its gaseous surroundings.

What does the Clausius-Clapeyron equation describe?

The quantitative relation between a substance’s vapor pressure and its temperature.

What is enthalpy of vaporization?

The amount of heat energy required to vaporize one mole of the liquid.

What is sublimation?

The transition from the solid phase directly into the gaseous state, bypassing the liquid state.

What is deposition?

The process in which gaseous substances condense directly into the solid state, bypassing the liquid state.

What does a phase diagram combine plots of?

Pressure versus temperature for the liquid-gas, solid-liquid, and solid-gas phase-transition equilibria of a substance.

What is a triple point?

The temperature/pressure condition where all three states (solid, liquid, gas) exist simultaneously.

What is a critical point?

The specific temperature and pressure at which liquid and gas phases have the same density and are indistinguishable from each other.

What are crystalline solids?

Solids in which its molecules, atoms, or ions are in specific patterns with long-range, repeating order.

What are amorphous solids?

Solids in which its molecules, atoms, or ions do not have any long-range order.

What are ionic solids?

Solids composed of positive and negative ions that are held together by electrostatic attractions.

What are metallic solids?

Solids in which the atoms within are held together by metallic bonding.

What are covalent network solids?

Solids in which the atoms are held together by a network of covalent bonds.

What are molecular solids?

Solids composed of neutral molecules.

What is a unit cell?

The basic repeating unit of the arrangement of atoms, ions, or molecules in a crystalline solid.

What is the coordination number?

The number of other particles each particle is in contact with.