Here's why:

* Kinetic Energy: As temperature increases, the molecules in both the solid and the liquid gain more kinetic energy. This means they move around faster and collide more frequently.

* Breaking Bonds: The increased kinetic energy helps overcome the forces holding the solid's molecules together (the lattice structure), making it easier for them to break apart and dissolve into the liquid.

* Increased Interaction: The faster-moving molecules of both the solid and the liquid interact more frequently and with greater force, leading to a greater dissolving rate.

Exceptions:

While this is generally true, there are some exceptions:

* Gases: The solubility of gases in liquids *decreases* with increasing temperature. This is because higher temperatures cause gas molecules to escape from the liquid more readily.

* Certain Salts: A few salts, like lithium sulfate (Li₂SO₄), actually become *less* soluble as the temperature rises.

Important Note:

The specific effect of temperature on solubility can vary depending on the specific solid and liquid involved. However, in general, raising the temperature makes it easier for most solids to dissolve.