Final answer:
If K_sp increases with rising temperature, the reaction is endothermic because the system absorbs heat, shifting the equilibrium towards the products and increasing K_sp.
Step-by-step explanation:
If the solubility product constant, Ksp, increases with increasing temperature, this indicates that the reaction is endothermic. According to Le Châtelier's Principle, when a system at equilibrium is disturbed by a change in temperature, pressure, or concentration, the system will shift its equilibrium position to counteract the effect of the disturbance. In an endothermic reaction, heat is absorbed from the surroundings, and so increasing the temperature will shift the equilibrium to the right, favoring the formation of products, thereby increasing the value of Ksp. Conversely, in an exothermic reaction where heat is released, increasing temperature would shift the equilibrium to the left, favoring the reactants and reducing the value of Ksp.