Gen Chem Red Terms Final Exam

Polarizability

Measure of how easy or difficult it is for another electrostatic charge to distort a molecule’s charge distribution

Dispersion forces

Fleeting, temporary dipoles resulting in weak electrostatic forces between molecules when very close together

Instantaneous dipoles

Result from constant motion of electrons in molecules and atoms

Induced dipoles

Result when an instantaneous dipole in one molecule or atom distorts the electrons in a neighboring atom or molecules

Dipole-dipole attraction

Present only in polar molecules

Stronger with higher dipole moments

Usually stronger than dispersion forces

Molecules arrange to align opposite charges

Hydrogen bonding

Strong type of dipole-dipole attraction

Strongest IMF

Present in only certain polar molecules with N—H, O—H, F—H bonds

Cohesive forces

Attractions between identical molecules of a substance

Adhesive forces

Attractions between different types of molecules

Viscosity

The measure of a liquid’s resistance to flow

Surface tension

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

Capillary action

Liquid flow within a porous material due to attraction of the liquid to the surface of the material and to other liquid molecules

Vapor Pressure

The pressure exerted by a vapor in equilibrium with a liquid in a closed container at a given temperature

Enthalpy of vaporization

The energy required to vaporize one mole of a liquid substance at a temperature, it is always endothermic

Normal boiling point of a liquid

The temperature at which the liquid boils when the pressure above the liquid is 1 atm

Enthalpy of fusion

The energy required to melt one mole of a solid substance at a temperature, always endothermic

Enthalpy of sublimation

The energy required to convert one mole of a solid substance directly to the gaseous state, always endothermic

Phase diagram

A map for the phases of matter at given temperatures and pressures

Triple point

The temperature and pressure at which solid, liquid, and vapor of a substance are all in equilbrium

Critical point

The temperature and pressure above which a gas cannot be condensed into a liquid

Supercritical fluid

The high density, low viscosity phase intermediate between liquid adn gas

Crystalline solids

Solids in which atoms, ions, or molecules are arranged in a definite repeating pattern

Amorphous solids

Glassy or noncrystalline solids that lack an ordered internal structure

Ionic solid

Solid composed of cations and anions held together by strong electrostatic attractions

Hard, can be very brittle break not bend

Insulators as solids, electrically conductive when molten or dissolved

Metallic solid

Solid composed of metal atoms held together by metallic bonding of atomic nuclei in a delocalized “sea of electrons”

Lustrous, malleable, highly conductive,

Covalent network solid

Solid whose particles are held together by covalent bonds

High melting, hard, strong, not conductive

Molecular solid

Solid composed of neutral molecules held together by intermolecular forces of attraction

Simple cubic (sc) unit cell

Contains an atom at each of the corners of the unit cell cube; a total of one atom within the unit cell. Alpha Polonium is the only elemental form that adopts the sc structure

Coordination number: 6

Body-centered (bcc) cubic unit cell

Contains an atom at each of the corners of the unit cell cube and one interior atom at the center of the cube, coordination # is 8

Rate of reaction

Measure of the speed at which a reaction takes place

Average rate

Rate over an interval

Instantaneous rate

Rate at any time

Rate Law

Mathematical equation showing the dependence of reaction rate on the rate constant and the concentration of one or more reactants

Rate constant (k)

Proportionality constant in the relationship between reaction rate and concentrations of reactants and must be determined experimentally

Integrated Rate Law

Equation that relates the concentration of a reactant to elapsed time of reaction

Second-Order Reaction

Rate = k[A]²

1/[A] = kt + 1/[A]₀

Zero-Order Reaction

Rate = k[A]⁰ = k

[A] = -kt + [A]₀

Half-life

The time at which [A]t = [A]₀/2

Collision Theory Postulates

1. Rate of reaction is proportional to the rate of reactant collisions

2. Molecules most collide in the correct orientation

   1. Molecules must have adequate kinetic energy to hit with enough energy

Frequency factor (A)

A proportionality constant related to the relative number of collisions having an orientation capable of leading to product formation

Intermediates

Species that are produced in one step and consumed in later steps and do not appear in the net reaction

Molecularity

The number of atoms, molecules, or ions involved in an elementary reaction

Catalyst

A substance added to a reaction that increases the reaction rate without being consumed by the reaction

Homogeneous catalyst

Catalyst present in the same phase as the reactants

Hetereogeneous catalyst

Catalyst present in a different phase from the reactants, furnishing a surface at which a reaction can occur

Unimolecular reaction

A —> product

Have one reactant species

Rate = k[A]

Bimolecular reaction

A + B —> product OR A + A —> product

Have two particles colliding together

Rate = k[A][B] OR k[A]²

Termolecular reaction

Three particles simultaneously colliding

2A + B —> product

Rate = k[A]²[B]

Solvation

The formation of IMFs between solvent and solute particles; solvation favors solubility

Solutions

Homogenous mixtures made up of two or more substances

Solute

substance being dissovled

Solvent

Substance that is doing the dissolving

Electrolytes

Substances that dissolve in water and undergo a physical or chemical change to produce aqueous ions

Strong electrolytes

Have all of the dissolved compound yielding ions solvated by water

Weak electrolytes

Have only a small fraction of the dissolved compound yielding ions solvated by water; the remaining solute molecules are unionized neutral molecules solvated by water

Nonelectrolytes

Substances that do not produce ions when dissolved in water. Many moelcular solids dissolve in water, but do not yield ions

Saturated

Concentration is equal to its solubility

Solubility

The maximum concentration of a solute in a solvent under given conditons

Supersaturated

The concentration of solute now exceeds its solubility

Henry’s Law

The quantity of an ideal gas that dissolves in a definite volume of liquid is directly proportional to the pressure of the gas

Miscible

Mutually soluble in all proportions

Colligative property

Property of a solution that depends only on the concentration of a solute species

Vapor Pressure Lowering

Boiling Point elevation

Freezing point depression

Osmotic pressure

Molality (m)

The ratio of the total number of moles of solute to the mass of the solvent in kilograms

Raoult’s Law

The partial pressure exerted by any component of an ideal solution is equal to the vapor pressure of the pure component multiplied by its mole fraction in the solution

Osmosis

The diffusion of solvent molecules thorough a semipermeable membrane

Isotonic solutiosn

Equal osmotic pressure

Match the osmotic pressure of blood serum, normal cell function

Hypotonic solutiosn

Lower osmotic pressure than blood serum

Water gain for cells with possible rupture

Hypertonic solutions

Higher osmotic pressure than blood serum

Water loss from cells with crenation damage

Dispersed phase

The component present as relatively large soldi or liquid particles in a colloid

Dispersion medium

Solid, liquid, or gas in which collodial particles are dispersed

Emulsion

Colloid formed from immiscible liquids

Emulsifying agent

Amphiphilic substance used to stabilize the particles of some emulsions

Le Chatelier’s principle

If an equilibrium system is stressed, the system will experience a shift in response to the stress that re-establishes equilibrium

Homogeneous equilibria

Equilibria in which all reactants and products occupy the same phase

Heterogeneous equilibria

Equilibria in which reactants and products occupy two or more different phases

Chemical equilibrium

The state of a reversible reaction in which the forward and reverse processes occur at equal rates

Bronsted-Lowry Acid

A compound that donates a proton (H+) to another compound

Bronsted-Lowry Base

A compound that accepts a proton (H+) from another compound

Amphiprotic

Substances like water that can either lose a proton or gain a proton

Buffer

Mixture of appreciable amounts of a weak acid-base pair that resists change in pH when small amounts of acid or base are added

Buffer capacity

The amount of acid or base that can be added to a buffer before the pH changes significantly

Initial point

Only acid to be titrated is present (pH of strong or weak acid)

Midpoint

Half the needed number of moles of base added (buffer if weak acid)

Equivalence point

Neutralization with product only (hydrolysis if weak acid)

Past the equivalence point

Exceeds base (excess base determines pH)

Lewis acid

Accepts a pair of electrons

Lewis base

Donates a pair of electrons

Coordinate covalent bond

Forms when one of the atoms in the bond provides both binding electrons

Spontaneous process

Process that takes place without a continuous input of energy from an external source

Nonspontaneous process

Process that requires continual input of energy from an external source

Microstate

Possible configuration or arrangement of matter and energy within a system

Second law of thermodynamics

All spontaneous processes involve an increase in the entropy of the universe

Third Law of Thermodynamics

Entropy of a perfect crystal at absolute zero (0 K) is zero

Standard entropy

Entropy for one mole of a substance at 1 atm pressure; tabulated values are usually determined at 298.15 K

Galvanic cells

The electrochemical cells in which spontaneous oxidation-reduction reactions produce electrical energy

Standard hydrogen electrode

The reference for all half-cell potential values with an assigned value of 0 V for the oxidation reaction

Electrolysis

Process using electrical energy to cause a nonspontaneous process to occur

Electrolytic cell

Electrochemical cell in which an external source of electrical power is used to drive an otherwise nonspontaneous process

Batteries

Single or series of galvanic cells designed for use as a source of electrical power

Primary cell

Non-rechargeable battery, suitable for single use only

Secondary cell

Battery designed to allow recharging