Chemical Thermodynamics
Basic Terminology
➖System- Part of the universe under investigation.
➖Open System- A system which can exchange both energy and matter with its surroundings.
➖Closed System- A system which permits passage of energy but not mass, across its boundary.
➖Isolated system- A system which can neither exchange energy nor matter with its surrounding.
➖Surroundings- Part of the universe other than system, which can interact with it.
➖Boundary- Anything which separates system from surrounding.
➖State variables- The variables which are required to be defined in order to define state of any system i.e. pressure, volume, mass, temperature, surface area, etc.
➖State Functions- Property of system which depend only on the state of the system and not on the path. Example: Pressure, volume, temperature, internal energy, enthalpy, entropy etc.
➖Intensive properties- Properties of a system which do not depend on mass of the system i.e. temperature, pressure, density, concentration,
➖Extensive properties- Properties of a system which depend on mass of the system i.e. volume, energy, enthalpy, entropy etc.
➖Process- Path along which state of a system changes.
➖Isothermal process- Process which takes place at constant temperature
➖Isobaric process- Process which takes place at constant pressure
➖Isochoric process- Process which takes place at constant volume.
➖Adiabatic process- Process during which transfer of heat cannot take place between system and surrounding.
➖Cyclic process- Process in which system comes back to its initial state after undergoing series of changes.
➖Reversible process- Process during which the system always departs infinitesimally from the state of equilibrium i.e. its direction can be reversed at any moment.
➖Irriversible Process- This type of process is fast and gets completed in a single step. This process cannot be reversed. All the natural processes are of this type.
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