Definitions [3]
Define Triple point.
The triple point of water is that point where water in a solid, liquid and gas state co-exists in equilibrium and this occurs only at a unique temperature and a pressure.
Define Sublimation.
Sublimation is the process in which a solid changes directly into a gas on heating, without passing through the liquid state.
Definition: Change of State
A transition from one state to another is called a change of state (or phase change).
Or
The process of change from one state to another at a constant temperature is called the change of phase.
Key Points
Key Points: Practical Applications of State
- A change of state occurs when heat exchange causes a substance to transition between solid, liquid, and gas phases.
- Temperature remains constant during a phase change because heat energy changes molecular arrangement (potential energy), not molecular speed (kinetic energy).
- The heating curve has flat plateaus at the melting point (0 °C) and boiling point (100 °C) for water, with rising slopes in between.
