Unit 9: Thermodynamics

Vocabulary flashcards covering the key terms, laws, and equations of Unit 9: Thermodynamics.

Pressure

A physical quantity defined by the equation $P = \frac{F}{A}$.

Maxwell Boltmann Distribution

A distribution curve where the peak shifting to the right indicates an increase in temperature, and the area under the curve represents the number of particles in the system.

The Ideal Gas Law (Molar)

The gas law expressed as $PV = nRT$, where $n$ represents the amount of substance in moles.

The Ideal Gas Law (Molecular)

The gas law expressed as $PV = N k_b T$, where $N$ represents the number of molecules or atoms.

Combined Gas Law

The relation used to compare initial states to final states when moles are constant: $\frac{P_1 V_1}{T_1} = \frac{P_2 V_2}{T_2}$.

Area under a $P\text{ vs }V$ curve

The representation of work ($W$) on a pressure versus volume graph.

Thermal Energy Transfer

Energy transfer that occurs during thermal contact from high to low, where high-speed molecules of a hotter sample collide with lower-speed molecules of a cooler sample until thermal equilibrium is reached.

Internal Energy ($\Delta U$)

The energy of a gas that increases as $\Delta T$ increases because the speed of the molecules increases.

First Law of Thermodynamics

The fundamental thermodynamic law expressed by the equation $\Delta U = Q + W$.

Heat ($Q$)

The energy brought in or lost via heating or cooling, during which a temperature difference may not necessarily occur.

Work ($W$)

The change in energy accomplished via expansion or compression, given by $W = -P \Delta V$, where $W$ is positive (+$) for compression and negative (-$$) for expansion.

Isobaric

A thermodynamic condition or process characterized by constant pressure.

Isovolumetric

A thermodynamic condition or process characterized by constant volume.

Isothermal

A thermodynamic condition or process characterized by constant temperature.

Adiabatic

A thermodynamic process in which there is no heat transfer ($Q = 0$).

Specific Heat ($c$)

A material-specific property used in the formula $Q = mc\Delta T$, expressed in units of $\frac{\text{energy unit}}{\text{mass unit} \times \text{temperature unit}}$.

Thermal Conductivity

A rate of heat loss or gain described by $\frac{Q}{\Delta t} = \frac{k A \Delta T}{L}$, dependent on the material constant ($k$), surface area ($A$), temperature difference ($\Delta T$), and object length ($L$).

Entropy

The potential to spread, which is at a maximum at thermal equilibrium and is lowest in solids, higher in liquids, and highest in gases.

Second Law of Thermodynamics

The thermodynamic principle stating that entropy cannot decrease for a system.