Leidenfrost Expansion and Boiling on a Hot Surface

Boiling is a process in which a liquid undergoes a phase change to transform into a vapor due to the absorption of heat. When a liquid is heated beyond its boiling point, it begins to vaporize rapidly, forming bubbles within the liquid. These bubbles rise to the surface and release vapor into the surrounding environment. However, a phenomenon known as the Leidenfrost effect can occur under specific conditions.

The Leidenfrost Effect

The Leidenfrost effect describes a phenomenon where a liquid droplet placed on a surface much hotter than its boiling point can levitate and move across the surface. This effect occurs due to the formation of a vapor layer between the droplet and the hot surface, preventing direct contact and reducing heat transfer. The vapor layer acts as a cushion, allowing the droplet to glide over the surface with minimal resistance.

Leidenfrost Expansion

Leidenfrost expansion is a specific case of the Leidenfrost effect that occurs when a liquid droplet is placed on a hot surface that is significantly hotter than its boiling point. In this scenario, the droplet does not simply levitate, but it expands rapidly, creating a vapor cushion underneath it. This expansion is called the Leidenfrost expansion.

Explanation of Option D

The Leidenfrost expansion is related to the boiling of a liquid on a hot surface. When a liquid droplet is placed on a surface that is much hotter than its boiling point, it rapidly vaporizes and forms a vapor cushion. This vapor cushion causes the droplet to expand, and it can even move across the surface due to the reduced friction.

Other Options

- Option A: Condensation of vapor on a cold surface is not related to Leidenfrost expansion. Leidenfrost expansion occurs on a hot surface, whereas condensation occurs on a cold surface when vapor changes back into a liquid state.
- Option B: The exchange of heat between two solids is not directly related to Leidenfrost expansion. Leidenfrost expansion occurs when a liquid is in contact with a hot surface.
- Option C: Evaporation of a solution is not directly related to Leidenfrost expansion. Leidenfrost expansion occurs specifically when a liquid droplet is placed on a hot surface.

In conclusion, the correct answer is option D - Leidenfrost expansion is related to the boiling of a liquid on a hot surface.