CHEE2325 – Lecture 1
First law of thermodynamics:
- Energy cannot be created or destroyed but can change forms.
Systems:
- The part of the universe that we are considering, such as the earth, a mine,
an organ, etc.
- Surroundings are everything that is outside the system.
- A boundary is a real or imaginary surface that defines a system. It is not
necessarily rigid.
Types of systems:
- An open system (control volume) is one where energy and mass exchange
are possible.
- A closed system (control mass) is one where only energy exchange is
possible, not mass exchange.
- Neither energy nor mass exchange are possible in an isolated system.
Properties of systems:
- A property is any characteristic of a system. They can be either intensive or
extensive.
- An intensive property is independent of the mass of the system, e.g.,
temperature, pressure.
- An extensive property is dependent on the size or amount of matter in a
system, e.g., mass, length, volume.
- The ratio of two extensive properties is intensive.
Dimensions:
Primary Dimension Symbol Unit
Mass M kg
Length L m
Time t s
First law of thermodynamics:
- Energy cannot be created or destroyed but can change forms.
Systems:
- The part of the universe that we are considering, such as the earth, a mine,
an organ, etc.
- Surroundings are everything that is outside the system.
- A boundary is a real or imaginary surface that defines a system. It is not
necessarily rigid.
Types of systems:
- An open system (control volume) is one where energy and mass exchange
are possible.
- A closed system (control mass) is one where only energy exchange is
possible, not mass exchange.
- Neither energy nor mass exchange are possible in an isolated system.
Properties of systems:
- A property is any characteristic of a system. They can be either intensive or
extensive.
- An intensive property is independent of the mass of the system, e.g.,
temperature, pressure.
- An extensive property is dependent on the size or amount of matter in a
system, e.g., mass, length, volume.
- The ratio of two extensive properties is intensive.
Dimensions:
Primary Dimension Symbol Unit
Mass M kg
Length L m
Time t s
