The First Law of Thermodynamics states that energy cannot be created or destroyed, only transferred or converted from one form to another. Mathematically, it is expressed as ΔU = Q - W, where ΔU is the change in internal energy, Q is the heat added to the system, and W is the work done by the system.
The Second Law of Thermodynamics states that the entropy of an isolated system always increases over time. Entropy is a measure of the randomness or disorder of a system, and the second law implies that natural processes tend to move towards a state of maximum entropy.
Gibbs free energy (G) is a thermodynamic potential that measures the maximum reversible work a system can perform at constant temperature and pressure. It is important because it predicts the spontaneity of a reaction; a negative ΔG indicates a spontaneous process.
In an isothermal process, the temperature of the system remains constant, while in an adiabatic process, there is no heat exchange with the surroundings, meaning the process occurs without gaining or losing heat. .
The phase rule, formulated by Josiah Willard Gibbs, is given by F = C - P + 2, where F is the degrees of freedom, C is the number of components, and P is the number of phases. It helps in determining the number of independent variables (temperature, pressure, composition) that can be altered without changing the number of phases in equilibrium.
The change in enthalpy (ΔH) for a reaction can be calculated using Hess's Law, which states that the total enthalpy change is the sum of the enthalpy changes for each step of the reaction pathway, regardless of the number of steps.
The Carnot cycle is a theoretical thermodynamic cycle proposed by Sadi Carnot, consisting of two isothermal processes and two adiabatic processes. It is important because it defines the maximum possible efficiency that any heat engine can achieve, serving as a standard for evaluating real engines.
Fugacity is a corrected pressure that accounts for non-ideal gas behavior. It is important in thermodynamics because it helps describe the chemical potential of real gases, making it easier to predict and calculate phase equilibria in non-ideal systems. .
Chemical potential is the change in the Gibbs free energy of a system when an additional amount of substance is introduced, keeping temperature and pressure constant. It is a crucial concept for understanding phase equilibria, reaction equilibria, and the distribution of substances between phases.
The Van der Waals equation is an equation of state that modifies the ideal gas law to account for the finite size of molecules and the attractive forces between them. It is significant because it provides a more accurate description of the behavior of real gases, particularly at high pressures and low temperatures.