Thermodynamics and Electrochemistry Practice Exam Review

Comprehensive vocabulary flashcards covering basic laws of thermodynamics, phase changes, calorimetry, chemical kinetics, electrochemistry, and colligative properties based on practice exam content.

First Law of Thermodynamics

States that the change in internal energy equals the work plus the heat transferred ($\Delta E = q + w$).

Expansion Work

The work done by a system calculated as $w = -P\text{ext} \times \triangle V$, where $1\text{ L} \times \text{atm} = 101.3\text{ J}$.

Cyclic Process

A process (A→B→C→D→A) where the change in internal energy ($\Delta E$) is equal to zero.

Isothermal Process

A process involving an ideal gas where the change in internal energy ($\Delta E$) must be zero because the temperature remains constant.

Endothermic

A classification of a reaction or process, such as boiling a liquid or a cold pack reaction involving $NH_4NO_3(s)$, where heat is absorbed.

Exothermic

A classification of a process, such as condensation of a gas into a liquid or solid, where heat is released.

Bomb Calorimeter

An apparatus used to measure the heat of combustion; heat is calculated using the heat capacity ($C$) and the temperature change ($\triangle T$) as $q = C \times \triangle T$.

Hess's Law

A method used to calculate the enthalpy change ($\Delta H$) of a target reaction by summing or manipulating the enthalpy changes of other known reactions.

Standard Enthalpy of Formation (\Delta H_f)

The heat change accompanying the formation of one mole of a compound from its elements, such as $-826\text{ kJ/mol}$ for $Fe_2O_3(s)$.

Second Law of Thermodynamics

States that the total entropy in the universe ($\Delta S_{\text{univ}}$) is increasing for a spontaneous process.

Third Law of Thermodynamics

States that the entropy of pure crystalline substances at $0\text{ K}$ is equal to zero.

Microstates

The number of different possible arrangements of a system; for example, $2\text{ mol}$ of gas at $0.5\text{ atm}$ and $398\text{ K}$ has more microstates than a system at $0\text{ K}$.

Sign of \Delta S (System)

Entropy change is positive when a molecule breaks into smaller molecules, the number of moles of gas increases, or phase transitions occur from solid to liquid to gas.

Gibbs Free Energy Equation

The relationship used to determine spontaneity: $\Delta G = \Delta H - T\text{ }\triangle S$.

Temperature Dependence of Spontaneity

If $\Delta H < 0$ and $\Delta S < 0$, the reaction is spontaneous at low temperatures only; if $\Delta H > 0$ and $\Delta S < 0$, the reaction is non-spontaneous at all temperatures.

Equilibrium (Thermodynamic Conditions)

The state where the reaction quotient $Q$ equals the equilibrium constant $K$, and the change in free energy (\Delta G) is equal to zero.

Standard Free Energy and Equilibrium

The mathematical relationship expressed as $\Delta G^{\circ} = -RT\text{ ln }K$, where $R = 8.314\text{ J/K} \times \text{mol}$.

Oxidizing Agent

A substance that facilitates oxidation by being reduced itself; examples include ions like $Pb^{2+}$, $Ag^+$, or $Cu^{2+}$.

Galvanic Cell

An electrochemical cell that utilizes spontaneous chemical reactions to produce electrical energy, consisting of oxidation at one electrode and reduction at the other.

Concentration Cell

A galvanic cell in which both electrodes have the same half-reactions but differ in the concentration of the electrolyte solutions.

Electrolysis Calculation

Determining the time ($t$) needed to plate a mass of metal using current ($I$) and Faraday's constant, based on the moles of electrons transferred.

Face Centered Cubic Structure (fcc)

A unit cell lattice where atoms are shared by surrounding cells; an atom at the corner of a cubic unit cell is shared equally by $8$ unit cells.

Hydrogen Bonding

A strong intermolecular force found in compounds where hydrogen is bonded to highly electronegative atoms, such as in $NH_3$ or $HF$.

Clausius-Clapeyron Equation

Relates the vapor pressure and temperature to the heat of vaporization ($\Delta H_{\text{vap}}$) to calculate boiling points at different pressures.

Colligative Properties

Properties of solutions that depend on the number of solute particles, including boiling point elevation, osmotic pressure ($\Pi = iMRT$), and vapor pressure lowering.

Raoult's Law

States that the vapor pressure of a solution component is equal to its mole fraction multiplied by the vapor pressure of the pure component.