Isothermal process maintains constant temperature (ΔT = 0). Occurs when system contacts thermal reservoir through slow heat exchange. Derived from Greek words meaning "equal heat". Can happen in any system with temperature regulation
A degree of freedom is an independent parameter in a physical system. A deterministic system has six degrees of freedom. A system with rotational or vibrational motion can have more than six degrees
Heat capacity is the amount of heat needed to raise a unit temperature change. SI unit is joule per kelvin (J/K). Specific heat capacity is heat capacity divided by mass
Boltzmann constant (kB) relates thermal energy of particles to gas temperature. Defined as 1.380649×10−23 joules per kelvin in SI units. One of seven defining constants in 2019 SI revision
Energy cannot be created or destroyed, only transformed. Heat and thermodynamic work are two main forms of energy transfer. Internal energy is a property of a system, not just heat or work
Gibbs free energy is maximum non-pressure-volume work possible in closed systems at constant temperature and pressure. It provides necessary conditions for chemical reactions under these conditions. Maximum work can only be achieved in completely reversible processes