Question

How can the solubility of any substance like water increase with heat?

Answer 1

A substance dissolves because of the force of "hydration". The attraction of water molecules is greater than the force that holds the particles in some form of the lattice. The regular arrangement of atoms is disrupted and the solid dissolves. As the temperature increases, the water molecules move around more, causing more disruption of the lattice, with a greater force. This allows a greater amount of solid to be dissolved in water, which is an increase in the solubility.