Chemistry and Thermodynamics Practice Flashcards

This set of vocabulary flashcards covers high-yield terminology, recognition rules, spontaneity conditions, and fundamental equations for thermodynamics and energy calculations.

Exothermic

A process where heat leaves the system and $\Delta H < 0$.

Endothermic

A process where heat enters the system and $\Delta H > 0$.

Spontaneous

A chemical process characterized by $\Delta G < 0$.

Nonspontaneous

A chemical process characterized by $\Delta G > 0$.

Entropy ($S$)

A measure of disorder or freedom where larger values signify more disorder; gases usually possess the most.

$$\Delta S < 0$$

Indicates that the system is becoming more ordered, such as during gas compression or condensation.

State functions

Properties that depend only on the current state of the system, including $U$, $H$, $S$, $G$, $P$, $V$, and $T$.

Not state functions

Variables that are path-dependent and not properties of the state, specifically heat ($q$) and work ($w$).

Extensive properties

Characteristics that depend on the amount of matter present, such as mass, volume, and internal energy.

Intensive properties

Characteristics that do not depend on the amount of matter present, such as temperature, pressure, and specific heat.

Standard formation reaction

A reaction that forms exactly $1\,mol$ of a compound from its constituent elements in their standard states.

Products minus reactants

The method used to calculate $\Delta H$, $\Delta S$, and $\Delta G$ using values from standard tables.

Reaction Quotient ($Q$)

The ratio of products over reactants where the stoichiometric coefficients from the balanced equation become exponents.

Photon energy

Property of light where a shorter wavelength results in higher energy.

Spontaneous at all $T$

The condition occurring when $\Delta H < 0$ and $\Delta S > 0$.

Never spontaneous

The condition occurring when $\Delta H > 0$ and $\Delta S < 0$.

Spontaneous at low $T$

The condition occurring when $\Delta H < 0$ and $\Delta S < 0$.

Spontaneous at high $T$

The condition occurring when $\Delta H > 0$ and $\Delta S > 0$.

$$q = mc\Delta T$$

The equation used when a problem provides mass, specific heat, and temperature change.

$$\Delta E = q + w$$

The equation used when a question specifies heat ($q$) and work ($w$).

$$\Delta G = \Delta H - T\Delta S$$

The equation used when given the enthalpy change, entropy change, and temperature.

$$\Delta G = \Delta G^{\circ} + RT\ln(Q)$$

The equation used for calculations involving pressures/concentrations or nonstandard conditions.

$$\Delta G^{\circ} = -RT\ln(K)$$

The equation used when solving for the equilibrium constant ($K$).

$$E = \frac{hc}{\lambda}$$

The equation used to determine photon energy or wavelength ($\lambda$).