System and Surrounding PDF

Created by Turbolearn AI System and Surrounding A system is a part of the universe in which observations are made, while the surrounding is a part of the universe excluding the system. The universe is the sum of the system and the surrounding. Types of Systems There are three types of systems:...

Created by Turbolearn AI System and Surrounding A system is a part of the universe in which observations are made, while the surrounding is a part of the universe excluding the system. The universe is the sum of the system and the surrounding. Types of Systems There are three types of systems: Open system: a system that exchanges both energy and matter with the surrounding. Example: hot coffee in an open vessel. Closed system: a system that exchanges energy but not matter with the surrounding. Example: hot coffee in a closed vessel. Isolated system: a system that does not exchange energy or matter with the surrounding. Example: hot coffee in a thermoflask. Properties of a System A system has two types of properties: Extensive properties: properties that depend on the amount of matter in the system. Examples include: Energy Internal energy Volume Enthalpy Mass Entropy Intensive properties: properties that are independent of the amount of matter in the system. Examples include: Density Pressure Temperature Molar volume Specific heat capacity Viscosity Refractive index Page 1  Created by Turbolearn AI An extensive property is a property that depends on the amount of matter in the system, while an intensive property is a property that is independent of the amount of matter in the system. State and Path Functions State function: a function that depends only on the initial and final state of the system. Examples include: Temperature Internal energy Volume Enthalpy Mass Entropy Path function: a function that depends on the path taken by the system. Examples include: Heat Work Thermodynamic Processes Process Description Equation Thermodynamic a process in which the temperature of the system process remains constant a process in which heat transfer with the Adiabatic process Q=0 surrounding does not take place a process in which the volume of the system Isochoric process ΔV = 0 remains constant a process in which the pressure of the system Isoboric process ΔP = 0 remains constant Sign Conventions Heat absorbed by the system: positive Heat released from the system: negative Work done by the system: negative Work done on the system: positive Internal Energy Page 2  Created by Turbolearn AI Internal energy is the total energy of the system under a given condition. It is a state function and an extensive property. The internal energy of a system can be changed in the form of heat and work by allowing heat to flow in and out of the system. First Law of Thermodynamics The first law of thermodynamics states that energy can neither be created nor destroyed, but it can be changed from one form to another. Free Expansion In a free expansion, the expansion of a gas in a vacuum, the work done is 0, the heat is 0, and the change in internal energy is also 0. Enthalpy Enthalpy is the total heat content of the system. It is the sum of the internal energy and the pressure-volume work of the system. H = U + PV Heat Capacity Heat capacity is the amount of heat required to raise the temperature of a system through 1 degree or 1 Kelvin. C = Q / ΔT Types of Heat Capacity Molar heat capacity: the heat capacity of 1 mole of a system Specific heat capacity: the heat capacity of a unit mass of a system Standard Enthalpy Changes Page 3  Created by Turbolearn AI Type Description Standard reaction the enthalpy change associated with a reaction in which all enthalpy substances are in their standard states Standard formation the enthalpy change when 1 mole of a compound is formed enthalpy from its elements in their stable states the enthalpy change when 1 mole of a substance undergoes Combustion enthalpy complete combustion the enthalpy change when 1 mole of an ionic compound is Lattice enthalpy dissociated into its gaseous constituent ions the enthalpy change when 1 mole of a substance is converted Atomization enthalpy into its gaseous atoms the enthalpy change when 1 mole of a solid is converted into Fusion enthalpy a liquid Vaporization the enthalpy change when 1 mole of a liquid is converted into enthalpy a gas the enthalpy change when 1 mole of a solid is converted into Sublimation enthalpy a gas Hess's Law Hess's law states that the enthalpy change in a reaction is the same whether it takes place in a single step or in multiple steps. Thermochemical Equations A thermochemical equation is a balanced chemical equation together with the value of the enthalpy of reaction. Spontaneous and Non-Spontaneous Processes Spontaneous process: a process that takes place by itself or with an initiation. Example: all natural processes. Non-spontaneous process: a process that takes place with an initiation or by itself, but requires the help of an external agency. Example: pumping of water. Entropy Page 4  Created by Turbolearn AI Entropy is a measure of the degree of disorder or randomness of a system. It is an extensive property and a state function. ΔS = Q / T Second Law of Thermodynamics The second law of thermodynamics states that the entropy of the universe always increases during every spontaneous process. Gibbs Free Energy Gibbs free energy is the maximum amount of available energy to do useful work. ΔG = ΔH - TΔS Third Law of Thermodynamics The third law of thermodynamics states that the entropy of a crystalline substance approaches 0 as the temperature approaches absolute 0. Page 5