Melting and Boiling Experiment for Schools, Teachers, and Students
Melting and boiling are physical processes where substances change their states due to the absorption of heat energy. Melting involves the transition from a solid to a liquid, while boiling is the transition from a liquid to a gas.
Melting:
- Melting is the process by which a solid changes into a liquid at a specific temperature called the melting point.
- During melting, the temperature of the substance remains constant as it absorbs heat.
- The heat absorbed is used to overcome the forces of attraction between particles in the solid state.
Key Points:
- Melting Point: The temperature at which a solid turns into a liquid.
- For example, the melting point of ice is 0°C or 273 K.
Boiling:
- Boiling is the process by which a liquid changes into a gas at a specific temperature called the boiling point.
- During boiling, the liquid absorbs heat energy, which overcomes the intermolecular forces holding the liquid together.
- The temperature remains constant during the boiling process.
Key Points:
- Boiling Point: The temperature at which a liquid turns into a gas.
- For example, the boiling point of water is 100°C or 373 K at atmospheric pressure.
Latent Heat:
- Latent heat is the heat energy absorbed or released during a phase change (melting, boiling, or condensation) without any change in temperature.
- Latent Heat of Fusion: Heat required to convert a unit mass of a solid into a liquid at its melting point.
- Latent Heat of Vaporization: Heat required to convert a unit mass of a liquid into a gas at its boiling point.
The formula for latent heat (L) is:
Q = mL
Where:
- Q: Heat absorbed or released (J)
- m: Mass of the substance (kg)
- L: Latent heat (J/kg)
Observations:
- During melting and boiling, the temperature remains constant despite the absorption of heat.
- The latent heat of fusion is needed to change a solid to a liquid.
- The latent heat of vaporization is required to change a liquid to a gas.
- Substances with stronger intermolecular forces have higher melting and boiling points.
Real-Life Examples:
- Ice melts into water at 0°C due to the absorption of heat.
- Water boils at 100°C to form steam in pressure cookers or open vessels.
- Latent heat is used in refrigeration systems to cool substances.
- Melting and boiling are used in metallurgy to mold metals at specific temperatures.
