8TH GRADE · CHANGE IN STATE OF AGGREGATION
Melting, crystallization and graphs
Melting temperature and phase transition energy.
The entire theory of the lesson is collected here; you can read it without an account. In interactive mode, the same theory appears as cards, followed by questions. with checking the answer and task, and progress is saved.
Basic Concepts
Melting and crystallization
Melting turns a solid into a liquid, and crystallization is the reverse transition.
For a pure crystalline substance, both processes at a given pressure occur at the same temperature.
Melting point
Temperature of phase equilibrium of solid and liquid states at a given pressure.
During the transition, the supplied energy destroys the ordered bonds, so the temperature temporarily remains constant.
Heating schedule
The graph shows the change in temperature over time and allows you to see areas of heating and phase transitions.
The inclined sections correspond to a change in temperature, and the horizontal sections correspond to the transformation of a substance at a constant temperature.
Physical quantities
Specific heat of fusion
The energy required to melt a unit mass of a substance at its melting point.
Unit: joule per kilogram ·
Lesson formulas
Heat of Melting
For melting at a constant temperature, the heat is equal to the specific heat of fusion multiplied by the mass.
Tasks on the topic
Statements, answer options and the walkthrough.