Internal energy Flashcards
What is internal energy ?
Energy stored by all the particles in a system
What does internal energy consist of ?
The total kinetic and potential energy that the particles possess
What is melting ?
solid changes into liquid when melting point is exceeded
What is boiling ?
liquid changes into gas when boiling point is exceeded
What is evaporation ?
the state change from a liquid to a gas but only on the surface of the liquid
e.g. hot tea (the smoke is the surface of the liquid evaporating)
What is sublimation ?
state change from a solid to a gas without melting
e.g. carbon dioxide does this at room temperature
How do we make these changes happen ?
- by increasing the internal energy
- this can be done by increasing the temperature / pressure of the particles
What is freezing ?
state change from a liquid to a solid when it is cooled
What is condensation ?
state change from a gas to a liquid when it is cooled
How do we make these changes happen ?
- by decreasing the internal energy
- this can be done by reducing the temperature or pressure
What is kinetic energy ?
the energy possessed by a moving object ( in this case particles moving around )
What is potential energy ?
the total of intermolecular forces between particles and their chemical bonds
Structure of a solid
- packed together in fixed positions
- can only vibrate on the spot
- fixed shape, fixed volume, high density
Structure of a liquid
- close together but not packed
- this means liquids can flow
- no fixed shape but a fixed volume
- medium density
Structure of a gas
- particles far apart
- often collide with walls of container
- no fixed shape or volume
- low density
