Heat is a form of energy that is transferred from one object or system to another due to a difference in temperature. Temperature is a measure of the average kinetic energy of particles in a substance, and as heat is transferred, it causes a change in temperature.
The three phases of matter are solid, liquid, and gas. In solids, the particles are tightly packed and have a fixed shape and volume. In liquids, the particles are close together but can move around, giving them a fixed volume but a variable shape. In gases, the particles are far apart and can move freely, giving them variable shape and volume. Heat can cause phase changes between these states by either adding or removing energy from the particles.
Specific heat is the amount of heat required to raise the temperature of one gram of a substance by one degree Celsius. Heat capacity, on the other hand, is the amount of heat required to raise the temperature of an entire object by one degree Celsius. It is typically measured in joules per degree Celsius (J/C).
During a phase change, the temperature of a substance remains constant as heat energy is used to break or form bonds between particles. For example, when water is heated from its solid state (ice) to its liquid state, the heat energy is used to break the bonds between the water molecules, causing the temperature to remain at 0 degrees Celsius until all the ice has melted.
Melting is the process by which a solid substance changes into a liquid state due to the addition of heat energy. Freezing is the opposite process, where a liquid substance changes into a solid state by removing heat energy. Both processes occur at a specific temperature known as the melting point and freezing point, respectively.