Chemistry SYSTEM AND SURROUNDINGS, EXTENSIVE AND INTENSIVE PROPERTIES

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SYSTEM AND SURROUNDINGS, EXTENSIVE AND INTENSIVE PROPERTIES

Some Basic Terms :

(i) `text(System)` : A specified part of the universe with real or imaginary boundaries, on which studies of `P`, `T` etc. are to be made. A room, an engine human body etc. are examples of system.

(ii) `text(Surrounding)` : The rest part of the universe, adjacent to real or imaginary boundaries of the system.

Universe = System + Surrounding

`text(Note)` : For practical purpose, surrounding means immediate surrounding rather than universe. For example in Lab experiment the room is considered as surrounding.

(iii) `text(Types of system)` :

`text(Based on Exchange of Mass and Energy)`

(a) `text(Isolated system)` : A system is said to be isolated if it cannot exchange matter and energy with the surroundings. Example :
coffee in a thermos flask.

(b) `text(Closed system)` : A system is said to be closed if it can exchange energy but not matter. Example : Coffee in a closed stainless steel flask.

(c) `text(Open system)` : A system is said to be open if it can exchange matter. Example : A thermos flask or a steel flask if not closed.

`text(Based on System composition)`

(a) `text(Homogeneous systems)` : A system having uniform nature throughout, made up of one phase only.

(b) `text(Heterogeneous system)` : A system not uniform throughout, consists of more than one phase.

(i) `text(System)` : A specified part of the universe with real or imaginary boundaries, on which studies of `P`, `T` etc. are to be made. A room, an engine human body etc. are examples of system.

(ii) `text(Surrounding)` : The rest part of the universe, adjacent to real or imaginary boundaries of the system.

Universe = System + Surrounding

`text(Note)` : For practical purpose, surrounding means immediate surrounding rather than universe. For example in Lab experiment the room is considered as surrounding.

(iii) `text(Types of system)` :

`text(Based on Exchange of Mass and Energy)`

(a) `text(Isolated system)` : A system is said to be isolated if it cannot exchange matter and energy with the surroundings. Example :
coffee in a thermos flask.

(b) `text(Closed system)` : A system is said to be closed if it can exchange energy but not matter. Example : Coffee in a closed stainless steel flask.

(c) `text(Open system)` : A system is said to be open if it can exchange matter. Example : A thermos flask or a steel flask if not closed.

`text(Based on System composition)`

(a) `text(Homogeneous systems)` : A system having uniform nature throughout, made up of one phase only.

(b) `text(Heterogeneous system)` : A system not uniform throughout, consists of more than one phase.

Properties of a System :

The state of a system is defined by a particular set of its measurable quantities called properties, by which a system can be described for example, Temperature (`T`), Pressure (`P`) and volume (`V`) defines the thermodynamics state of the system in the same way, as particle co-ordinate is defined by (`x`, `y`, `z`) co-ordinate in physics. Properties can be categorised into extensive and intensive properties, on the basis of dependance of system size or mass.

`text(Intensive property)` is one whose value is independent of the size (or mass) of the system.
`text(Extensive property)` is one whose value depends on the size (or mass) of the system.

`text(Intensive & Extensive properties)` :
(i) Extensive properties are additive but intensive properties are non additive.
(ii) Ratio of two extensive property gives an intensive property.
(iii) An extensive property can be converted into intensive property by defining it per mole/per gram/per litre.

The state of a system is defined by a particular set of its measurable quantities called properties, by which a system can be described for example, Temperature (`T`), Pressure (`P`) and volume (`V`) defines the thermodynamics state of the system in the same way, as particle co-ordinate is defined by (`x`, `y`, `z`) co-ordinate in physics. Properties can be categorised into extensive and intensive properties, on the basis of dependance of system size or mass.

`text(Intensive property)` is one whose value is independent of the size (or mass) of the system.
`text(Extensive property)` is one whose value depends on the size (or mass) of the system.

`text(Intensive & Extensive properties)` :
(i) Extensive properties are additive but intensive properties are non additive.
(ii) Ratio of two extensive property gives an intensive property.
(iii) An extensive property can be converted into intensive property by defining it per mole/per gram/per litre.

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